Transmission with integrated overload protection for legged robots

Abstract

An exemplary robot (300) includes: a motor (1300) disposed at a joint (403), or the joint is configured to control the movement of a component of the robot; a transmission device (1200) including an input member (1312) connected to the motor and configured to rotate with the motor, an intermediate member (1314), and an output member (1318), wherein the intermediate member is fixed so that when the input member rotates, the output member rotates at a different speed; a pad (1320) frictionally coupled to a side surface of the output member of the transmission device and coupled to the component of the robot; and a spring (1328) configured to apply an axial preload on the pad, wherein the axial preload defines a torque limit, and when the torque limit is exceeded by a torque load on the component of the robot, the output member of the transmission device slips relative to the pad.

Description

[0001] This application is a divisional application of the application with application date of December 13, 2017, application number 201780077209.X, and invention name “Transmission device with integrated overload protection for legged robots”. Technical Field

[0002] The present invention relates to a transmission with integrated overload protection for a legged robot. Background Art

[0003] An exemplary robot may have multiple components that form the legs and arms of the robot. The motion of these components may be controlled by actuators such as hydraulic cylinders and motors. The design of these actuators determines the operating characteristics of the robot, such as how quickly the robot can respond to commands and external disturbances. Design factors that affect the performance of the robot may include the moment of inertia of the actuator and the transmission ratio of the transmission coupled thereto, among other factors. Summary of the invention

[0004] The present invention describes a transmission device with integrated overload protection for a legged robot. In a first exemplary embodiment, the present invention describes a robot. The robot includes: (i) a motor, arranged at a joint, the joint being configured to control the movement of a member of the robot; (ii) a transmission device, including an input member, an intermediate member, and an output member connected to the motor and configured to rotate with the motor, wherein the input member is configured to engage the intermediate member and rotate in an open annular space defined by the intermediate member, wherein the intermediate member engages the output member, and wherein the intermediate member is fixed so that when the input member rotates, the output member rotates at a different speed; (iii) a pad, frictionally coupled to a side surface of the output member of the transmission device and coupled to the member of the robot; and (iv) a spring, configured to apply an axial preload on the pad, wherein the axial preload defines a torque limit, and when the torque limit is exceeded by the torque load on the member of the robot, the output member of the transmission device slips relative to the pad.

[0005] In a second exemplary embodiment, the present invention describes an assembly. The assembly includes: (i) a motor disposed at a joint configured to control motion of a member of a robot; a harmonic drive including a waveform generator coupled to the motor and configured to rotate with the motor, a flexible gear, and a rigid gear, wherein the flexible gear is fixed so that when the waveform generator rotates, the rigid gear rotates therewith at a different speed; (iii) a first pad frictionally coupled to a distal side surface of the rigid gear and coupled to the member of the robot; (iv) a second pad frictionally coupled to a proximal side surface of the rigid gear; and (v) a flexible member configured to apply an axial preload on the first and second pads, wherein the axial preload defines a torque limit, and when the torque limit is exceeded by a torque load on the member of the robot, the rigid gear slips relative to at least one of the first or second pads.

[0006] The foregoing is merely illustrative and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features can be understood by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 The configuration of a robot system is shown according to an exemplary embodiment.

[0008] Figure 2 A quadruped robot is shown according to an exemplary embodiment.

[0009] Figure 3 A bipedal robot is shown according to an exemplary embodiment.

[0010] Figure 4A A cross section of a robot leg with a screw actuator is shown according to an exemplary embodiment.

[0011] Figure 4B A cross section of an upper leg member is shown according to an exemplary embodiment.

[0012] Figure 5A According to an exemplary embodiment, a bracket is shown having at least one longitudinal channel disposed on an outer surface of the bracket.

[0013] Figure 5B An anti-rotation element is shown according to an exemplary embodiment.

[0014] Figure 5C A perspective view of an upper leg member and an anti-rotation element coupled thereto is shown according to an exemplary embodiment.

[0015] Fig. 6A A carriage is shown according to an exemplary embodiment, having rollers coupled thereto.

[0016] Figure 6B An upper leg member configured to receive a bracket and a track therein is shown according to an exemplary embodiment.

[0017] Figure 6C A top cross-sectional view of an upper leg member and components disposed therein is shown according to an exemplary embodiment.

[0018] Figure 7 According to an exemplary embodiment, a configuration with a pressed threaded shaft is shown.

[0019] Figure 8 According to an exemplary embodiment, a configuration with a threaded shaft under tension is shown.

[0020] Fig. 9 According to an exemplary embodiment, the upper leg member is shown offset relative to the hip joint.

[0021] Fig.10 According to an exemplary embodiment, the motor is shown offset from the upper leg member.

[0022] Fig.11 A robotic leg is shown according to an exemplary embodiment.

[0023] Fig. 12A A diagram of a harmonic drive is shown according to an exemplary embodiment.

[0024] Fig. 12B According to an exemplary embodiment, Fig. 12A Exploded view of the harmonic drive section in FIG.

[0025] Fig.13A An exemplary drive system with an integrated overload protection system is shown in accordance with an exemplary embodiment.

[0026] Fig. 13B According to an exemplary embodiment, Fig.13A A magnified view of the drive system in Figure 2.

[0027] Fig. 13C According to an exemplary embodiment, Fig.13A Exploded view of the drive system in the .

[0028] Fig.14 According to an exemplary embodiment, an alternative configuration of a drive system for a robotic component is shown.

[0029] Fig.15A An integrated motor controller assembly is shown according to an exemplary embodiment.

[0030] Fig. 15B Connecting a torque sensor and an output encoder to a controller is shown according to an exemplary embodiment.

[0031] Fig. 15C According to an exemplary embodiment, Fig.15A Thermal management of the components shown in .

[0032] Fig.15D A bottom view of a power stage printed circuit board is shown according to an exemplary embodiment

[0033] Fig.15E According to an exemplary embodiment, 12 wires are shown leading out of the stator of the motor.

[0034] Fig.15F A phase circuit board configured to engage a stator is shown according to an exemplary embodiment.

[0035] Figure 15G According to an exemplary embodiment, Fig.15A Exploded view of components shown. DETAILED DESCRIPTION

[0036] The following detailed description describes various features and operations of the disclosed system with reference to the accompanying drawings. The exemplary embodiments described herein are not limiting. Certain aspects of the disclosed system can be arranged and combined in various different configurations, all of which are contemplated herein.

[0037] Further, unless the context otherwise dictates, the features shown in each figure may be used in combination with each other. Thus, the drawings should generally be viewed as constituent aspects of one or more overall embodiments, with it being understood that not all of the features shown are necessary for every embodiment.

[0038] In addition, any enumeration of elements, blocks or steps in this specification or claims is for clarity. Thus, such enumeration should not be considered as requiring or implying that these elements, blocks or steps must be strictly performed according to a specific structure or in a specific order.

[0039] The term "substantially" means that the characteristics, parameters or values ​​described need not be achieved exactly, but a certain amount of deviation or difference may occur, for example, including tolerances, measurement errors, measurement accuracy limitations and other factors known in the art, but does not affect the effect provided by the characteristics.

[0040] I. Exemplary Robotic Systems

[0041] Figure 1An exemplary configuration of a robotic system that can be used in accordance with embodiments described herein is shown. The robotic system 100 can be configured to operate autonomously, semi-autonomously, and / or using guidance provided by a user(s). The robotic system 100 can be implemented in various forms, such as a bipedal robot, a quadrupedal robot, or some other structure. Furthermore, the robotic system 100 can also be referred to as a robot, a robotic device, or a mobile robot, among other names, and can be an exoskeleton device or a human assist device.

[0042] like Figure 1 As shown, the robotic system 100 may include a processor(s) 102, a data storage 104, and a controller(s) 108, which together may be part of a control system 118. The robotic system 100 may also include a sensor(s) 112, a power source(s) 114, a mechanical component 110, and an electrical component 116. However, the robotic system 100 is shown for purposes of illustration and may include more or fewer components. The various components of the robotic system 100 may be connected in any manner, including wired or wireless connections. Further, in some examples, the components of the robotic system 100 may be distributed among multiple physical entities rather than in a single physical entity. Other exemplary illustrations of the robotic system 100 may also exist.

[0043] The processor(s) 102 may operate as one or more general purpose hardware processors or special purpose hardware processors (e.g., digital signal processors, application specific integrated circuits, etc.). The processor(s) 102 may be configured to execute computer readable program instructions 106 and operate on data 107, the instructions and data being stored in a data memory 104. The processor(s) 102 may also interact directly or indirectly with other components of the robotic system 100, such as sensor(s) 112, power source(s) 114, mechanical components 110, and / or electrical components 116.

[0044] The data storage 104 can be one or more types of hardware storage. For example, the data storage 104 can include or take the form of one or more computer-readable storage media that can be read or accessed by the processor (one or more) 102. One or more computer-readable storage media may include volatile and / or non-volatile storage components, such as optical, magnetic, organic or another type of memory or storage, which can be integrated with the processor (one or more) 102 in whole or in part. In some embodiments, the data storage 104 can be a single physical device. In other embodiments, the data storage 104 can be implemented using two or more physical devices, which can communicate with each other via wired or wireless communications. As previously described, the data storage 104 can include computer-readable program instructions 106 and data 107. Data 107 can be any type of data, such as configuration data, sensor data, and / or diagnostic data, and there are other possibilities.

[0045] The controller 108 may include one or more circuits, digital logic units, computer chips, and / or microprocessors configured to (among other tasks) interface between any combination of mechanical components 110, sensor(s) 112, power source(s) 114, electrical components 116, control system 118, and / or a user of the robotic system 100. In some implementations, the controller 108 may be a special-purpose embedded device that is used to perform specific operations by one or more subsystems of the robotic system 100.

[0046] The control system 118 can monitor and physically change the operating state of the robotic system 100. In doing so, the control system 118 can serve as a link between some parts of the robotic system 100 (e.g., between the mechanical components 110 and / or the electrical components 116). In some cases, the control system 118 can serve as an interface between the robotic system 100 and another computing device. Further, the control system 118 can serve as an interface between the robotic system 100 and a user. For example, the control system 118 can include various components that communicate with the robotic system 100, including joysticks, buttons, and / or ports, etc. The exemplary interfaces and communications described above can be implemented via wired or wireless connections, or both. The control system 118 can also perform other operations for the robotic system 100.

[0047] During operation, the control system 118 may communicate with other systems of the robotic system 100 via wired or wireless connections, and may be further configured to communicate with one or more users of the robot. As one possible example, the control system 118 may receive input (e.g., from a user or from another robot) indicating an instruction to perform a particular gait in a particular direction and at a particular speed. A gait is a pattern of limb movement of an animal, robot, or other mechanical structure.

[0048] Based on the input, the control system 118 may perform operations to cause the robotic system 100 to move according to the requested gait. As another example, the control system may receive input indicating an instruction to move to a particular geographic location. In response, the control system 118 (perhaps with the assistance of other components or systems) may determine a direction, speed, and / or gait based on the environment through which the robotic system 100 moves to the geographic location.

[0049] The operations of the control system 118 may be performed by the processor(s) 102. Alternatively, the operations may be performed by the controller 108 or a combination of the processor(s) 102 and the controller 108. In some implementations, the control system 118 may be partially or completely located on a device other than the robotic system 100, and thus may at least partially remotely control the robotic system 100.

[0050] The mechanical components 110 represent the hardware of the robotic system 100 that enables the robotic system 100 to perform physical operations. As a few examples, the robotic system 100 may include physical components, such as leg(s), arm(s), and / or wheel(s). The physical components or other portions of the robotic system 100 may further include actuators arranged to move the physical components relative to each other. The robotic system 100 may also include one or more structural bodies for housing a control system 118 and / or other components, and may further include other types of mechanical components. The specific mechanical components 110 used in a given robot may vary based on the design of the robot, and may also be based on the operations and / or tasks that the robot may be configured to perform.

[0051] In some examples, the mechanical components 110 may include one or more removable components. The robotic system 100 may be configured to add and / or remove such removable components, which may involve assistance from a user and / or another robot. For example, the robotic system 100 may be configured to have removable arms, hands, feet, and / or legs so that these appendages may be replaced or changed as needed or desired. In some embodiments, the robotic system 100 may include one or more removable and / or replaceable battery units or sensors. Other types of removable components may also be included in some embodiments.

[0052] The robotic system 100 may include sensor(s) 112 arranged to sense aspects of the robotic system 100. The sensor(s) 112 may include one or more force sensors, torque sensors, velocity sensors, acceleration sensors, position sensors, proximity sensors, motion sensors, position sensors, load sensors, temperature sensors, touch sensors, depth sensors, ultrasonic range sensors, infrared sensors, object sensors, and / or cameras, among other possibilities. In some examples, the robotic system 100 may be configured to receive sensor data from sensors that are physically separate from the robot (e.g., sensors located on other robots or in the robot's operating environment).

[0053] The sensor(s) 112 may provide sensor data to the processor(s) 102 (perhaps by way of data 107) to allow the robotic system 100 to interact with its environment and to monitor the operation of the robotic system 100. The sensor data may be used by the control system 118 for evaluation of various factors for activation, movement, and deactivation of the electrical components 116 and the mechanical components 110. For example, the sensor(s) 112 may capture data corresponding to the terrain of the environment or the location of nearby objects, which may aid in environmental recognition and navigation. In an exemplary configuration, the sensor(s) 112 may include radar (e.g., for long-range object detection, distance determination, and / or velocity determination), LIDAR (e.g., for short-range object detection, distance determination, and / or velocity determination), sonar (e.g., for underwater object detection, distance determination, and / or velocity determination), The robotic system 100 may include a camera (e.g., for motion capture), one or more cameras (e.g., stereo cameras for 3D vision), a global positioning system (GPS) transceiver, and / or other sensors for capturing information in the environment in which the robotic system 100 operates. The sensor(s) 112 may monitor the environment in real time and detect obstacles, terrain features, weather conditions, temperature, and / or other aspects of the environment.

[0054] Further, the robotic system 100 may include sensor(s) configured to receive information indicative of a state of the robotic system 100, including sensor(s) 112 that may monitor the states of various components of the robotic system 100. The sensor(s) 112 may measure system activity of the robotic system 100 and receive information based on the operation of various features of the robotic system 100, such as the operation of extendable legs, arms, or other mechanical and / or electrical features of the robotic system 100. The data provided by the sensor(s) 112 may enable the control system 118 to determine errors in operation and monitor the overall operation of components of the robotic system 100.

[0055] As an example, the robotic system 100 may use force sensors to measure loads on various components of the robotic system 100. In some embodiments, the robotic system 100 may include one or more force sensors on an arm or leg to measure loads on an actuator that moves one or more components of the arm or leg. As another example, the robotic system 100 may use one or more position sensors to sense the position of an actuator of the robotic system. For example, such a position sensor may sense the state of extension, retraction, or rotation of an actuator on an arm or leg.

[0056] As another example, the sensor(s) 112 may include one or more velocity and / or acceleration sensors. For example, the sensor(s) 112 may include an inertial measurement unit (IMU). The IMU may sense velocity and acceleration relative to a gravity vector in a world coordinate system. The velocity and acceleration sensed by the IMU may then be converted to velocity and acceleration of the robotic system 100 based on the position of the IMU in the robotic system 100 and the motion characteristics of the robotic system 100.

[0057] The robotic system 100 may include other types of sensors not specifically described herein. Additionally or alternatively, the robotic system may use specific sensors for purposes not enumerated herein.

[0058] The robotic system 100 may also include one or more power sources (one or more) 114 configured to supply power to various components of the robotic system 100. Among other possible power systems, the robotic system 100 may include a hydraulic system, an electrical system, a battery, and / or other types of power systems. As an exemplary illustration, the robotic system 100 may include one or more batteries configured to provide electrical charge to components of the robotic system 100. Some of the mechanical components 110 and / or the electrical components 116 may each be connected to a different power source, may be powered by the same power source, or may be powered by multiple power sources.

[0059] Any type of power source may be used to power the robotic system 100, such as an electric power source or a gasoline engine. Additionally or alternatively, the robotic system 100 may include a hydraulic system configured to use fluid power to power the mechanical components 110. Various types of charging methods may be used to charge the power source(s) 114, such as a wired connection to an external power source, wireless charging, combustion, or other examples.

[0060] The electrical components 116 may include various mechanisms capable of processing, transferring, and / or providing electrical charge or electrical signals. In a possible example, the electrical components 116 may include wires, circuits, and / or wireless communication transmitters and receivers to enable the operation of the robotic system 100. The electrical components 116 may cooperate with the mechanical components 110 to enable the robotic system 100 to perform various operations. For example, the electrical components 116 may be configured to provide power from the power source(s) 114 to the various mechanical components 110. Further, the robotic system 100 may include an electric motor. Other examples of electrical components 116 may also exist.

[0061] Although in Figure 1 Although not shown in the drawings, the robot system 100 may include a body to which the appendages and components of the robot system may be connected or housed. As such, the structure of the body may vary in some examples and may further depend on the specific operations that a given robot has been designed to perform. For example, a robot developed to carry heavy loads may have a wide body that enables placement of the load. Similarly, a robot designed to reach high speeds may have a narrow body that does not have a lot of weight. Further, the body and / or other components may be developed using various types of materials (e.g., metal or plastic). In other examples, the robot may have a body that has a different structure or is made of various types of materials.

[0062] The body and / or other components may include or carry sensor(s) 112. These sensors may be located at various locations on the robotic system 100, such as on the body and / or on one or more appendages, among other examples.

[0063] On its body, the robotic system 100 may carry a load, such as a type of cargo to be transported. The load may also represent an external battery or other type of power source (e.g., a solar panel) that the robotic device 100 may utilize. Carrying a load represents one exemplary use for which the robotic system 100 may be configured, but the robotic system 100 may also be configured to perform other operations.

[0064] As described above, the robotic system 100 may include various types of legs, arms, wheels, etc. As described above, the robotic system 100 may include various types of legs, arms, wheels, etc. In general, the robotic system 100 may be configured to have zero or more legs. An embodiment of a robotic system with zero legs may include wheels, tracks, or some other form of locomotion. An embodiment of a robotic system with two legs may be referred to as a bipedal approach, and an embodiment with four legs may be referred to as a quadrupedal approach. Embodiments with six or eight legs are also possible. For purposes of illustration, bipedal and quadrupedal embodiments of the robotic system 100 are described below.

[0065] Figure 2 A quadruped robot 200 is shown according to an exemplary embodiment. Among other possible features, the robot 200 can be configured to perform some of the operations described herein. The robot 200 includes a control system, and legs 204A, 204B, 204C, 204D are connected to a body 208. Each leg may include a respective foot 206A, 206B, 206C, 206D that can contact a surface (e.g., a ground surface). Further, the robot 200 is shown as having a sensor(s) 210, and can carry a load on the body 208. In other examples, the robot 200 may include more or fewer components, and thus may include Figure 2 Components not shown.

[0066] The robot 200 may be Figure 1 The robot system 100 is shown as a physical representation, or may be based on other configurations. Thus, the robot 200 may include one or more of a mechanical component 110, a sensor (one or more) 112, a power source (one or more) 114, an electrical component 116, and / or a control system 118, among which other possible components or systems may exist.

[0067] The configuration, location, and / or structure of the legs 204A-204D may vary in the exemplary embodiment. The legs 204A-204D enable the robot 200 to move relative to its environment, and may be configured to operate with multiple degrees of freedom, enabling different locomotion techniques. Specifically, the legs 204A-204D may enable the robot 200 to travel at various speeds according to the mechanical characteristics described in different gaits. The robot 200 may use one or more gaits to travel in the environment, which may involve selection based on speed, terrain, operational needs, and / or energy efficiency.

[0068] Further, different types of robots may use different gaits due to design variations. Although some of the differences may have specific names (e.g., walk, trot, run, jump, gallop, etc.), the distinctions between gaits may overlap. Gaits may be classified based on footfall pattern—the location on the surface for placing the feet 206A-206D. Similarly, gaits may also be classified based on walking mechanics.

[0069] The body 208 of the robot 200 connects the legs 204A-204D and can house various components of the robot 200. For example, the body 208 can include or carry sensor(s) 210. These sensors can be any sensors covered by the meaning of sensor(s) 112, such as cameras, LIDAR, or infrared sensors. Further, the location of the sensor(s) 210 is not limited to Figure 2 Thus, the sensor(s) 210 may be positioned at various locations on the robot 200, such as on the body 208 and / or on one or more of the legs 204A-204D, among other examples.

[0070] Figure 3 FIG. 2 shows a bipedal robot 300 according to another exemplary embodiment. Similar to the robot 200, the robot 300 may correspond to Figure 1 The robot system 100 is shown and can be configured to perform some of the embodiments described herein. Thus, similar to the robot 200, the robot 300 can include one or more of a mechanical component 110, a sensor (one or more) 112, a power source (one or more) 114, an electrical component 116, and / or a control system 118.

[0071] For example, robot 300 may include legs 304 and 306 connected to body 308. Each leg may include one or more members connected by joints and configured to operate with various degrees of freedom relative to each other. Each leg may also include a respective foot 310 and 312, which may contact a surface (e.g., a ground surface). Similar to robot 200, legs 304 and 306 may enable robot 300 to travel at various speeds according to the mechanical characteristics described in gait. However, robot 300 may utilize a different gait than robot 200, which is due at least in part to the difference between bipedal and quadrupedal capabilities.

[0072] The robot 300 may also include arms 318 and 320. These arms may assist in object manipulation, load carrying, and / or balancing the robot 300. Similar to the legs 304 and 306, each arm may include one or more members connected by joints and configured to operate with various degrees of freedom relative to each other. Each arm may also include a respective hand 322 and 324. The robot 300 may use the hands 322 and 324 to grasp, rotate, pull and / or push objects. The hands 322 and 324 may include various types of appendages or accessories, such as fingers, grippers, welding tools, cutting tools, etc.

[0073] The robot 300 may also include sensor(s) 314, corresponding to sensor(s) 112, and configured to provide sensor data to its control system. In some cases, the positions of these sensors may be selected to reflect the anthropomorphic structure of the robot 300. Thus, as Figure 3 As shown, the robot 300 may include a visual sensor (eg, a camera, an infrared sensor, an object sensor, a distance sensor, etc.) in its head 316 .

[0074] II. Exemplary Electromechanical Actuators for Robotics

[0075] In some examples, hydraulic actuators can be used to actuate components of the robot. The hydraulic system can include a pump and an accumulator at a central location on the robot and is configured to provide pressurized hydraulic fluid to actuators connected to components of the robot through pipes and / or hoses. In this configuration, the actuation inertia of the pump and accumulator is unrelated to the inertia provided to the ground surface when the robot moves. Since there is no correlation between the inertias, the hydraulic robot system is characterized by a high bandwidth for positioning and force control responsiveness. However, the hydraulic system has disadvantages such as potential hydraulic fluid leakage, complex piping connections, and existing hydraulic power units are not suitable for smaller robots.

[0076] Electromechanical actuators can alleviate at least some of the disadvantages of hydraulic actuators because there are no leaks or complex pipe connections involved in operating electromechanical actuators. Further, electromechanical systems can be more efficient than hydraulic systems. However, electromechanical actuators can also have disadvantages compared to hydraulic systems. For example, although for a given strength, the moment of inertia of a robot component driven by a hydraulic actuator may have a linear relationship with the diameter of the actuator, for a given strength, the moment of inertia of a robot component driven by an electromechanical actuator is proportional to the square of the diameter of the rotating assembly of the actuator and is affected by the gear ratio of the transmission. Further, the reflected inertia of the hydraulic actuator is negligible compared to the inertia of the robot's components (such as legs), while the reflected inertia of the electromechanical depends on the inertia of the motor and transmission multiplied by the square of the transmission ratio. Thus, for large robots, electromechanical actuators can have high inertia, which limits the responsiveness and operating characteristics of the robot.

[0077] For robots of smaller size, electromechanical actuators, as described herein, can be designed to achieve high operating characteristics compared to corresponding hydraulic actuators. Disclosed herein are systems, actuators, configurations, and apparatus that can reduce the moment of inertia of robot components to allow high peak torque to be obtained to provide sufficiently high acceleration suitable for high performance robots.

[0078] a. Example screw actuator for robot joints

[0079] In some examples, the robot's knee joint may experience high accelerations, such as from actuating the robot to move quickly (e.g., running or jogging). High accelerations may also occur when the robot experiences a disturbance at its legs, and the robot responds by causing the legs, and in particular the knee joint, to accelerate at high speeds to maintain balance. In some examples, a motor may be coupled to the robot's knee joint such that rotational movement of the motor causes the robot's lower leg member to rotate relative to an upper leg member coupled to the lower leg member at the knee joint. In this configuration, the motor's moment of inertia may limit the robot's responsiveness and may thereby reduce the effectiveness of the force control strategy of the lower leg member.

[0080] Further, if a transmission is coupled to the motor, and the transmission has a specific transmission ratio that allows speed reduction and torque amplification, the moment of inertia at the knee joint is proportional to the square of the transmission ratio. Therefore, a higher transmission ratio that allows higher torque will result in a higher moment of inertia, thereby reducing the responsiveness of the robot.

[0081] Reducing the moment of inertia at the knee joint can improve the responsiveness of the robot. In one example, a screw actuator can be used to drive the knee joint of the robot because the screw actuator is light and slender and thus has a low inertia compared to other actuator configurations. Further, using a screw actuator allows for a reduction in distal mass at the knee, which in turn can allow for higher acceleration capabilities.

[0082] Figure 4A A cross section of a robot leg with a screw actuator 400 is shown according to an exemplary embodiment. The motor 402 is located at or near the hip joint 403 of the robot. In other examples, the motor 402 can be located at the upper leg portion of the robot. Regardless of whether the motor 402 is located at the upper leg portion or the hip joint 403, the mass of the motor 402 is moved away from the knee joint 404. Thus, these configurations can reduce the distal mass at the robot knee joint 404 and, therefore, reduce the moment of inertia at the hip joint 403.

[0083] The screw actuator 400 is a mechanical linear actuator that converts rotational motion into linear motion with little friction. In one example, the screw actuator 400 may be a planetary roller screw type and may include a threaded shaft 406 and a nut 408. The threaded shaft 406 may have a multi-start V-shaped thread on its periphery. The V-shaped thread provides a spiral raceway for a plurality of rollers radially arranged around the threaded shaft 406 and enclosed by the nut 408. The rollers are arranged in a radial direction. Figure 4A Not shown in the figure to reduce visual clutter in the drawing.

[0084] Nut 408 is screwed on its inner circumferential surface to engage with the V-shaped threads of threaded shaft 406. The pitch of the threads of threaded shaft 406 can be the same as the pitch of the internal threads of nut 408. Rollers are in rotational contact with threaded shaft 406 and nut 408 and act as low friction transmission elements between the two. The rollers can have single-start threads with convex tooth flanks that limit friction when the rollers are in contact with threaded shaft 406 and nut 408. The rollers can orbit the threaded shaft 406 as they rotate (in the manner of planetary gears relative to a sun gear), and can therefore be called planetary or satellite rollers.

[0085] The motor 402 is coupled to the threaded shaft 406, and thus when the motor 402 rotates, the threaded shaft 406 rotates therewith. The rotation of the threaded shaft 406 effects axial or longitudinal travel of the nut 408.

[0086] The motor 402 and the screw actuator 400 are housed in the body (eg, a machined aluminum body) of an upper leg member 410 of the robot. The upper leg member 410 is coupled to a lower leg member 412 at a knee joint 404.

[0087] The nut 408 is received in the proximal end 413 of the carrier 414 and engages with the carrier 414 at the shoulder 416 so that as the nut 408 travels along the threaded shaft 406, the carrier 414 also moves linearly in the upper leg member 410. As used herein, the term "proximal end" refers to the end of the carrier 414 that is closer to the motor 402.

[0088] The nut 408 is axially constrained in the proximal end 413 of the bracket 414 by the shoulder 416 and the nut 417, which axially captures the nut 408 in the bracket 414. Further, the nut 408 can be rotationally constrained relative to the bracket 414 to prevent the nut 408 from rotating relative to the bracket 414. For example, the nut 408 can be coupled to the bracket 414 via a key-keyway configuration.

[0089] The linkage mechanism is coupled to the bracket 414 to help convert the linear motion of the bracket 414 into a rotational motion of the lower leg member 412 relative to the upper leg member 410 about the knee joint 404. As an example, the linkage mechanism can include a first link 418 (e.g., a connecting rod) coupled to the distal end 420 of the bracket 414. As used herein, the term "distal end" refers to the end of the bracket 414 that is farthest from the motor 402. In another example, the first link 418 can be lug-mounted to the bracket 414 at another location closer to the motor 402.

[0090] The first link 418 can be coupled to the second link 422 at the joint 424, and the second link can be coupled to the knee joint 404 at the knee pivot 426. The lower leg member 412 is also coupled to the knee joint 404 at the knee pivot 426. In this configuration, the linear motion of the bracket 414 causes the first link 418 to move, thereby causing the second link 422 and the lower leg member 412 to rotate about the knee pivot 426. Other linkage mechanisms can be used. For example, a four-bar mechanism can be used to achieve different transmission curve shapes.

[0091] The direction of rotation of the motor 402 determines the direction of rotation of the lower leg member 412 relative to the upper leg member 410. For example, if the motor 402 rotates in a given direction (e.g., clockwise), the nut 408 and the bracket 414 can extend and push the first link 418. As a result, the lower leg member 412 rotates relative to the upper leg member 410. Figure 4A From the perspective of the observer, the second link 422 rotates in a clockwise direction about the knee pivot 426. Figure 4A Lower leg member 412 may also be rotated clockwise, as viewed from an observer's perspective, thereby pushing foot 428 against surface 430, for example.

[0092] Conversely, if the motor 402 is rotated in the opposite direction (eg, counterclockwise), the nut 408 and the bracket 414 may retract and pull the first link 418. As a result, the Figure 4A From the perspective of an observer, the second link 422 rotates counterclockwise about the knee pivot 426, thereby causing the lower leg member 412 to curl upward. Thus, alternating between clockwise and counterclockwise rotation of the motor 402 can cause the robot to perform steps (e.g., walking or running at a specific pace).

[0093] In one example, the motor 402 may include an encoder 431. The encoder 431 is configured to generate a signal indicating the rotational position of the rotor of the motor 402. The encoder 431 may provide information indicating the rotational position of the rotor to a controller of the robot. The controller may perform closed-loop feedback control of the rotational position of the motor 402 in order to accurately position the nut 408 in the upper leg member 410.

[0094] By placing the motor 402 closer to the hip joint 403 and using the screw actuator 400, the distal mass at the knee joint 404 is reduced. Further, using the screw actuator 400 as a speed reducer instead of a rotary gearbox can reduce the effective moment of inertia because the screw actuator 400 has a reduced moment of inertia compared to a rotary gearbox.

[0095] Figure 4B A cross section of the upper leg member 410 is shown according to an exemplary embodiment. Figure 4BAs shown, the upper leg member 410 can receive a bearing bracket 432. The bearing bracket 432 can be seated along a conical seat 434 that protrudes inwardly from the inner surface of the upper leg member 410.

[0096] The bearing bracket 432 houses a bearing 435 configured to allow the threaded shaft 406 to rotate freely. The outer diameter of the outer race of the bearing 435 engages the inner peripheral surface of the bearing bracket 432. The outer race of the bearing 435 is held against a shoulder 436 formed by a stepped surface on the inner peripheral surface of the bearing bracket 432.

[0097] Further, the threaded shaft 406 includes a shoulder 438 formed with a stepped surface on the outer peripheral surface of the threaded shaft 406. The shoulder 438 engages the inner race of the bearing 435. In this way, the bearing 435 is axially constrained between the shoulder 438 and the shoulder 436.

[0098] like Figure 4B As shown, the first link 418 is coupled to the distal end 420 of the bracket 414 via a pin 440. The first link 418 forms an angle relative to the longitudinal axis 442 of the threaded shaft 406. Thus, when the threaded shaft 406 rotates so that the nut 408 and the bracket 414 push the first link 418, the first link 418 can impart a reaction force on the bracket 414, which is transmitted to the nut 408 and the threaded shaft 406. The reaction force can be decomposed into a longitudinal axial force component 444 acting along the longitudinal axis 442 and a radial or eccentric force component 446 acting perpendicular to the inner surface of the upper leg member 410 and the longitudinal axis 442.

[0099] In order to reduce the effect of the eccentric force component 446 and the friction caused by it, a sliding bearing 448 is installed between the outer peripheral surface of the bracket 414 at the distal end 420 and the inner peripheral surface of the upper leg member 410. The sliding bearing 448 can be configured to reduce friction and facilitate the axial movement of the bracket 414 in the upper leg member 410. In particular, the sliding bearing 448 can be configured to allow the eccentric force component 446 on the nut 408 to react to the upper leg member 410 and constrain the force caused by the interaction between the first link 418 and the bracket 414 along the axis 442. In one example, the sliding bearing 448 can be used manufacture.

[0100] In one example, another slide bearing 450 can be mounted between the outer peripheral surface of the bracket 414 at the proximal end 413 and the inner peripheral surface of the upper leg member 410. In these examples, the slide bearings 448 and 450 can operate as guide bushings that allow the bracket 414 to experience the axial force component 444 while reacting to the eccentric force component 446 and reducing friction.

[0101] As described above, the axial force component 444 acting on the bracket 414 is transmitted to the nut 408 and the threaded shaft 406. The threaded shaft 406 engages the bearing 435 at the shoulder 438, and thereby the bearing 432 experiences the axial force component 444. The axial force component 444 is then transmitted from the bearing 435 to the bearing bracket 432 via the shoulder 436.

[0102] An axial load cell 440 may be disposed on an outer peripheral surface of the bearing bracket 432. Thus, the axial load cell 440 also experiences an axial force component 444, which is imparted to the bracket 414 and the threaded shaft 406 during operation of the robot leg. The axial load cell 440 may generate an electrical signal proportional to the axial force component 444 imparted to the threaded shaft 406. The electrical signal may be provided to a controller of the robot or a leg member of the robot.

[0103] In one example, the controller can use encoder 431 and axial load cell 440 to perform various control strategies based on the state of the robot, the robot's environment, and the commanded acceleration. For example, in a first control strategy, the controller can perform closed-loop position control on the rotational position of motor 402 as described above. In a second control strategy, the controller can perform closed-loop force control on the force applied by foot 428 on surface 430. This control strategy can allow high acceleration capabilities for the robot leg. In a third control strategy, the controller can perform closed-loop position and force control, where the force control loop can be used to cushion the action of the robot leg. These control strategies are examples for demonstration, and other control strategies can be implemented.

[0104] In some examples, the bracket 414 and components coupled thereto (eg, the nut 408 ) may be prevented from rotating about the longitudinal axis 442 via an anti-rotation mechanism or configuration. Figures 5A-5C According to an exemplary embodiment, an anti-rotation configuration for bracket 414 is shown. Specifically, Figure 5A According to an exemplary embodiment, a bracket 414 is shown having at least one longitudinal channel 500 disposed on an outer surface of the bracket 414. Figure 5A As shown, the longitudinal passage 500 is disposed between the distal end 420 and the proximal end 413 of the bracket 414. In some examples, the longitudinal passage 500 can take the form of a groove machined longitudinally on the outer surface of the bracket 414.

[0105] Figure 5B An anti-rotation element 502 is shown according to an exemplary embodiment. The anti-rotation element 502 includes a curved plate 504 and a projection 506 protruding from a concave surface of the curved plate 504. The anti-rotation element 502 is configured to be coupled to an outer surface of the upper leg member 410 such that the projection 506 protrudes radially inwardly in the upper leg member 410 and engages the longitudinal channel 500.

[0106] As an example, the curved plate 504 can have holes, such as hole 508. The outer surface of the upper leg member 410 can have corresponding holes. Fasteners can be used to couple the curved plate 504 to the upper leg member 410 via the holes in the curved plate 504 and the corresponding holes in the upper leg member 410. Further, the upper leg member 410 can have a central hole corresponding to and configured to receive the projection 506 therethrough.

[0107] Figure 5C A perspective view of an upper leg member 410 and an anti-rotation element 502 coupled thereto is shown according to an exemplary embodiment. The outer surface of the upper leg member 410, or a portion thereof, can be curved to match the curvature of the concave surface of the curved plate 504. In this way, the concave surface of the curved plate 504 can conform to the contour or topography of the outer surface of the upper leg member 410 (when coupled thereto).

[0108] The bump 506 protrudes through the outer surface of the upper leg member 410 and engages the longitudinal channel 500 of the bracket 414. With this configuration, the bump 506 prevents the bracket 414 from rotating about the longitudinal axis 442 as the bracket 414 moves axially in the upper leg member 410. In some examples, the bump 506 can be made of a material that reduces friction with the longitudinal channel 500 as the bracket 410 moves in the upper leg member 410 (e.g., Teflon).

[0109] Other exemplary anti-rotation mechanisms may be implemented. Figures 6A-6C Another anti-rotation mechanism is shown according to an exemplary embodiment. Specifically, Fig. 6A A carriage 600 is shown having roller(s) 602 coupled thereto according to an exemplary embodiment. Fig. 6A One roller 602 is shown on one side of the carriage 600. Another roller can be coupled to the carriage 600 on its other side. In some examples, more rollers similar to roller 602 can be coupled to the carriage 600. Roller 602 is configured to roll in a track 604, and a roller corresponding to roller 602 on the other side of the carriage 600 is configured to roll in a track 606 parallel to track 604. The two rollers are collectively referred to as roller(s) 602.

[0110] Tracks 604 and 606 are configured to constrain roller(s) 602 therein. In this manner, tracks 604 and 606 can operate as tracks for roller(s) 602, such that tracks 604 and 606 and roller(s) 602 form a roller element bearing configuration. This configuration reduces friction when carriage 600 moves in a robot leg. In addition, in one example, for example, with Fabricated sliding bearings 607 may be provided around the outer surface of the bracket 600 to engage the inner surface of the robot leg, further reducing friction.

[0111] The two rails 604 and 606 have holes formed therein, such as holes 608A, 608B, 608C, 608D, and 608E, which can be configured to receive fasteners to fixedly mount the rails 604 and 606 to the robot leg, as shown below for Figure 6B Because the rails 604 and 606 are fixedly mounted to the robot legs and at the same time they constrain the motion of the roller(s) 602 therein, the carriage 600 does not rotate about its longitudinal axis 609 .

[0112] Figure 6B An upper leg member 610 is shown according to an exemplary embodiment, which is configured to receive the bracket 600 and the rails 604 and 606 therein. The upper leg member 610 can be similar to the upper leg member 410, but can additionally have a hole pattern 612 on an outer surface thereof. The hole pattern 612 corresponds to the holes provided in the rails 604 and 606. For example, the holes 614A, 614B, 614C, and 614D in the hole pattern 612 can correspond to the holes 608A, 608B, 608C, and 608D of the rail 604, respectively. Fasteners can then be used to fixedly mount the rails 604 and 606 in the upper leg member 610.

[0113] Figure 6C A top cross-sectional view of the upper leg member 610 and components disposed therein is shown according to an exemplary embodiment. Figure 6C As shown, roller bracket 616 is coupled to the distal end of bracket 600 and is disposed perpendicular to longitudinal axis 609. Roller(s) 602 are coupled to roller bracket 616 and configured to roll in tracks 604 and 606 while being constrained therein. Specifically, at least one roller 602 is coupled to a first end of roller bracket 616 and rolls in track 604, and another roller 602 is coupled to a second end of roller bracket 616 opposite the first end and configured to roll in track 606. Although Fig. 6A and 6C Tracks 604 and 606 are shown as separate components from upper leg member 610 , but in some examples, tracks 604 and 606 may alternatively be integrated with and built into an inner surface of upper leg member 610 .

[0114] The axial load cell 618 is disposed closer to the motor 402 than the axial load cell 440 described above. The axial load cell 618 may also be of a different type. For example, while the axial load cell 440 is shown as a column load cell, the axial load cell 618 is a bending beam load cell. Other styles and locations of load cells may also be used.

[0115] As the robot moves and Figure 4A The lower leg member 412 is shown rotated relative to the upper leg member 410 or 610, and the threaded shaft 406 experiences alternating compressive and tensile forces. For example, if the threaded shaft 406 is rotated in a direction (e.g., counterclockwise) that causes the nut 406 to retract, thereby pulling the bracket 414 and the first link 418, the threaded shaft 406 is stretched. However, if the threaded shaft 406 is rotated in the opposite direction (e.g., clockwise) that causes the nut 406 to extend, thereby pushing the bracket 414 and the first link 418, the threaded shaft 406 is compressed.

[0116] Further, in order for the robot to move, the lower leg member 412 (which may contact a ground surface (e.g., surface 430)) is pushed against the ground surface. Even when the robot is standing in position, the lower leg member 412 applies a pushing force against the ground surface to keep the robot standing and balanced. Whether the robot is moving or standing, the pushing force against the ground surface may cause a tensile force or a compressive force in the threaded shaft 406 based on the geometric configuration of the first link 418 relative to the knee pivot 426.

[0117] Figure 7 A configuration having an extruded threaded shaft 406 is shown according to an exemplary embodiment. Figure 7 The construction shown is similar to Figure 4A In this configuration, the first link 418 is coupled to the lower leg member 412 at a joint 424, which is located between the knee pivot 426 and the foot 428. As a result, when the lower leg member 412 is pushed against the surface 430, a compressive force is applied along the length of the first link 418 in the direction of arrow 700. This compressive force is transmitted to the bracket 414 and to the threaded shaft 406 through the nut 408. Thus, in this configuration, the threaded shaft 406 is compressed.

[0118] Figure 8 According to an exemplary embodiment, a configuration with a threaded shaft 406 that is under tension is shown. In this configuration, the first link 418 is coupled to the lower leg member 412 at the joint 800 so that the knee pivot 802 is disposed between the joint 800 and the foot 428. As a result, when the lower leg member 412 is pushed against the surface 430, a tension force is applied along the length of the first link 418 in the direction of the arrow 804. This tension force is transmitted to the bracket 414 and to the threaded shaft 406 through the nut 408. Thus, in this configuration, the threaded shaft 406 is under tension.

[0119] Figure 7 However, in some examples, the robot may experience environmental conditions that cause the forces in the threaded shaft 406 to be high enough to cause a jam therein. In these examples, the robot may use Figure 8 The peak extension force of the robot leg is usually higher than the peak retraction force, and Figure 8 The construction allows the threaded shaft 406 to be stretched during high extension force events.

[0120] Other configurations for the robotic legs may be implemented. Fig. 9 According to an exemplary embodiment, the upper leg member 410 is shown offset relative to the hip joint 403. As shown, the assembly including the upper leg member 410 and the components therein is offset relative to the hip joint 403. This configuration can alleviate packaging limitations caused by limiting the length of the upper leg member 410 based on the position of the hip joint 403. In other words, for example, relative to Figure 4A The structure, in Fig. 9 In the configuration of the upper leg member 410, the length of the upper leg member 410 can be increased. Alternatively, in other examples, the upper leg member 410 can be offset relative to the hip joint 403 to help reduce the overall length from the knee pivot 426 to the hip joint 403.

[0121] Further, in the configurations described above, the motor 402 is arranged according to the threaded shaft 406. In some examples, these configurations can make the upper leg member 410 or 610 relatively long. Other configurations can be used to make the upper leg member 410 or 610 shorter.

[0122] Fig.10 According to an exemplary embodiment, the motor 402 is shown offset from the upper leg member 410. As shown, by removing the motor 402 from the upper leg member 410 and allowing it to be offset relative to the upper leg member 410, the upper leg member 410 can be shortened. In this configuration, a belt drive can be provided as a speed reduction pre-stage between the motor 402 and the threaded shaft 406. The speed reduction pre-stage can allow the speed reduction ratio of the screw actuator 400 to be reduced. Reducing the speed reduction ratio of the screw actuator 400 can reduce the moment of inertia, resulting in higher operating characteristics, as described below.

[0123] Typically, a roller screw can provide more bearing points or areas in a given space than a ball screw, and can thereby reduce contact stresses. Also, a roller screw is more compact for a given load capacity while providing similar efficiency (e.g., 75%-90%) at low to medium speeds as a ball screw, and maintaining relatively high efficiency at high speeds. Compared to a ball screw, a roller screw can further achieve better positioning accuracy, load rating, stiffness, speed, acceleration, and life. However, a ball screw can be cheaper than a roller screw, and it is therefore desirable to use a ball screw for some applications.

[0124] b. Example transmission with integrated clutch for overload protection

[0125] The moment of inertia affects the position and force control responsiveness of the robot. The effective moment of inertia at the joints of the robot may depend on the moment of inertia of the motors coupled to the joints and the moment of inertia of the transmission coupled to the motors. The transmission may have a specific transmission ratio that allows for speed reduction and torque amplification, and the effective moment of inertia at the joint is proportional to the square of the transmission ratio. Therefore, a higher transmission ratio that allows for higher torque results in a higher moment of inertia, thereby reducing the responsiveness of the robot.

[0126] In general, a large motor and a low gear ratio can provide a lower output inertia than a small motor and a high gear ratio, but at the expense of more mass. Thus, using a large motor to achieve higher torque and strength results in a high moment of inertia, which reduces the responsiveness of the robot. Even with a small motor, a transmission with a high gear reduction ratio results in a high effective moment of inertia.

[0127] When selecting a motor for a robot joint, one approach is to determine the maximum torque that the joint is expected to experience and select a motor that can achieve this maximum torque. However, this approach results in a high effective moment of inertia. For example, in the event of an impact, such as when the robot's leg accidentally hits the ground surface or the leg experiences a sudden impact caused by an object, the impact will cause the motor to rotate at high speed to respond to the impact and keep the robot balanced. In particular, the impact causes the input side of the motor and the transmission to accelerate rapidly. The final inertial torque is amplified by the transmission ratio, causing high torque at the joint, which can damage the transmission and / or leg structure. The reflected inertia in this case can be determined based on the sum of the motor moment of inertia and the transmission coefficient multiplied by the square of the transmission reduction ratio. Selecting a motor that can achieve the maximum torque that occurs in such an impact situation will result in a large motor with a correspondingly large moment of inertia.

[0128] Another approach may be to achieve impedance matching. Specifically, the motor and transmission at the joint are selected to have a reflected or output inertia that is equal to the inertia of the robot component controlled by the joint. This approach can increase the acceleration capability of the joint.

[0129] In another example, the motor can be used to directly drive the member without a transmission coupled thereto. In this way, the reflected inertia can be reduced. However, without a transmission, there is no torque amplification and the maximum torque is limited by the torque achievable by the motor. Even if a transmission with a reduced transmission ratio is used, the motor may then be larger in size to compensate for the reduced torque amplification at the transmission, thereby resulting in excessive weight and size.

[0130] The improved methods presented herein can achieve the integration of an overload protection system in a motor or transmission. The overload protection system can isolate the transmission from the high torque experienced in a crash situation. In this way, a transmission with a reduced size that can achieve appropriate torque and acceleration can be selected. A smaller transmission can have a lower inertia, thereby allowing a smaller motor to achieve the desired acceleration because the overall inertia is reduced.

[0131] The systems and apparatus disclosed herein relate to integrating a clutch into a harmonic drive transmission to allow reduction in the size, mass and inertia of the motor and transmission to improve the responsiveness of the robot. The integrated clutch system as described below can be used, for example, at the hip joint or other joints of a robot.

[0132] Fig.11 A robotic leg is shown according to an exemplary embodiment. As described above, a screw actuator such as screw actuator 400 can be used instead of a rotary gearbox to drive a knee joint 404. Screw actuator 400 can allow for a reduction in distal mass at knee joint 404. Distal mass affects the inertia of the leg, and having mass closer to the hip can reduce the inertial torque required at the hip joint. Screw actuator 400 can also reduce the effective moment of inertia because screw actuator 400 has a reduced moment of inertia compared to a rotary gearbox.

[0133] In addition, a motor and transmission having an overload protection system as described herein can be coupled to the hip joint 403 to reduce the moment of inertia there. For example, the motor and transmission can be mounted at the hip joint 403 along one or both of the x-axis 1100 and the y-axis 1102.

[0134] According to an exemplary embodiment, Fig. 12A A diagram of operating a harmonic drive 1200 is shown, and Fig. 12B An exploded view of a harmonic drive 1200 is shown. As used herein, the harmonic drive 1200 is an exemplary transmission system to operate as a speed reducer and torque amplifier. The harmonic drive is characterized by zero backlash characteristics, a wide range of reduction ratios, weight and space savings relative to other transmission systems, high position accuracy and repeatability. However, other transmission systems (e.g., cycloidal transmissions) may be used.

[0135] like Fig. 12A As shown, the harmonic drive 1200 includes three main components: an input member, which may be referred to as a waveform generator 1202; an intermediate member, which may be referred to as a flexspline 1204; and an outer member, which may be referred to as a rigid spline 1206. Fig. 12BAs shown, the waveform generator 1202 may include a thin raced ball bearing 1208 mounted to an elliptical hub 1210. The elliptical hub 1210 is Fig. 12B It may not appear elliptical because the difference in size between its major and minor axes is small. Waveform generator 1202 operates as a torque converter and is connected to the input shaft from the motor and thereby operates as an input to harmonic drive 1200 .

[0136] The flexspline 1204 is a thin cylindrical cup-shaped member, which is made of alloy steel, for example, and has external teeth 1212 on the outer peripheral surface of the open end of the cup-shaped member. The flexspline 1204 is radially flexible or bendable, but is torsionally rigid. When the waveform generator 1202 is inserted into the flexspline 1204, the waveform generator 1202 engages with the external teeth 1212 of the flexspline 1204 at the open end of the flexspline 1204. As a result, the open end of the flexspline 1204 takes an elliptical shape.

[0137] The circular spline 1206 is a rigid ring with internal teeth 1214. When the harmonic drive 1200 is assembled, the internal teeth 1214 of the rigid spline 1206 engage the external teeth 1212 of the flexible spline 1204 across the main axis 1216 of the elliptical waveform generator 1202. The rigid spline 1206 can have more teeth than the flexible spline 1204. For example, the rigid spline 1206 can have two more teeth than the flexible spline 1204.

[0138] In some examples, the flexible gear 1204 is used as an output and can thereby be connected to the output flange, while the rigid gear 1206 is fixedly mounted. In other examples, the rigid gear 1206 is used as an output and can thereby be connected to the output flange, while the flexible gear 1204 is fixedly mounted. In the exemplary description provided below, the rigid gear 1206 is allowed to rotate and can be connected to the output, while the flexible gear 1204 is fixedly mounted. However, other configurations may be used.

[0139] When the elliptical hub 1210 of the waveform generator 1202 rotates, the flexible gear 1204 is deformed into the shape of the elliptical hub 1210 and does not slide on the outer circumferential surface of the ball bearing 1208. As a result, the external teeth 1212 of the flexible gear 1202 engage the internal teeth 1214 of the rigid gear 1206 at two opposite areas across the main axis 1216 of the waveform generator 1202. For every 180 degrees of rotation of the waveform generator 1202, the internal teeth 1214 of the rigid gear 1206 advance one tooth relative to the external teeth 1212 of the flexible gear 1204. Thus, each complete rotation of the waveform generator 1202 can cause the rigid gear 1206 to move two teeth relative to the flexible gear 1204 from its original position.

[0140] With a harmonic drive such as the harmonic drive 1200, a wide range of gear reduction ratios (e.g., ratios from 30:1 to 320:1) can be achieved in a small space. As described above, having a low ratio can reduce the reflected or output inertia of the transmission (i.e., the harmonic drive 1200) to contribute to the high performance of the robot. In order to protect the harmonic drive 1200 in high impact situations, an overload protection system is integrated therein, as described below.

[0141] According to an exemplary embodiment, Fig.13A shows an exemplary drive system with an integrated overload protection system, Fig. 13B Shows Fig.13A A magnified view of the drive system in Fig. 13C Shows Fig.13A Exploded view of the drive system. Figures 13A-13C are described together. Figures 13A-13C The drive system in can be coupled to either or both axes 1100 and 1102 of the hip joint 403, or any other joint of the robot. The following description refers to the motor and transmission at the hip joint 403 for driving the robot leg. However, the system described herein can be used at any other joint to drive any other member of the robot (e.g., an arm).

[0142] The motor 1300 is mounted in a housing 1302 at the robot hip joint 403. The housing 1302 is coupled to the robot via flange 1306 and fasteners, such as fasteners 1308A and 1308B.

[0143] The rotor of motor 1300 is coupled to shaft 1310 configured to rotate with the rotor. A waveform generator 1312, which may be similar to waveform generator 1202, is coupled to and configured to rotate with shaft 1310. Waveform generator 1312 engages with a toothed portion of a flexible gear 1314, which is similar to flexible gear 1204. Flexible gear 1314 is fixedly mounted to load cell or torque sensor 1316 via fasteners (e.g., fasteners 1315A and 1315B), which in turn is fixedly mounted to housing 1302. External teeth of the toothed portion of flexible gear 1314 engage internal teeth of a rigid gear 1318, which may be similar to rigid gear 1206. The teeth of flexible gear 1314 and rigid gear 1318 are in a Figures 13A-13C Not shown in the figure to reduce visual clutter in the drawing.

[0144] With this configuration, when the waveform generator 1312 rotates with the shaft 1310, the rigid gear 1318 rotates about the longitudinal axis 1319 because the flexible gear 1314 is fixed. The proximal side surface of the rigid gear 1318 engages the first clutch pad 1320, and the distal side surface of the rigid gear 1318 engages the second clutch pad 1322. Herein, the proximal side refers to the side closer to the motor 1300, and the distal side refers to the side farther from the motor 1300.

[0145] The clutch pads 1320 and 1322 have friction materials mounted to their surfaces, which engage with corresponding surfaces of the rigid gear 1318. Thus, as long as the clutch pads 1320 and 1322 are sufficiently pre-compressed against or biased toward the corresponding surfaces of the rigid gear 1318, the clutch pads 1320 and 1322 rotate with the rigid gear 1318.

[0146] The clutch pad 1320 is also engaged and coupled to the pressure plate 1324. Similarly, the clutch pad 1322 is also engaged and coupled to the output flexure 1326. In one example, the clutch pad 1320 can be bonded to the pressure plate 1324 via any type of adhesive, and the clutch pad 1322 can be bonded to the output flexure 1326 via any type of adhesive. Other fasteners can be used to couple the clutch pad 1320 to the pressure plate 1324 and the clutch pad 1322 to the output flexure 1326. In one example, the pressure plate 1324 can be made of aluminum. However, other materials are also possible. Also, in another example, the clutch pads 1320 and 1322 can be glued to the rigid gear 1318 and allowed to slide relative to the pressure plate 1324 and the output flexure 1326. In another example, the clutch pads 1320 and 1322 are not glued to any other components and may be allowed to slide along any four surfaces, two surfaces for each clutch pad.

[0147] The Belleville spring 1328 is disposed between the robot member 1330 (e.g., a leg member) and the output flexure 1326. The Belleville spring 1328 applies an axial biasing force on the output flexure 1326 to apply an axial preload on the clutch pad 1322. The axial preload on the clutch pad 1322 similarly applies a preload to the clutch pad 1320 because the axial preload is transmitted to the clutch pad 1320 through the rigid gear 1318, which is constrained by the pressure plate 1324.

[0148] The axial preload can keep the clutch pads 1320 and 1322 frictionally coupled to the rigid gear 1318 until a predetermined torque limit is exceeded. If the torque limit is exceeded, the static friction limit of the clutch pads 1320 and 1322 is exceeded, and the rigid gear 1318 can slip relative to the clutch pads 1320 and 1322. Therefore, the torque limit can be referred to as a slip torque.

[0149] The torque limit is based on the spring rate of the Belleville spring 1328. A shim, such as shim 1332, may be added between the Belleville spring 1328 and the robot member 1330 to change the axial preload on the clutch pads 1320 and 1322 and thereby change the torque limit.

[0150] The output flexure 1326 can be torsionally rigid but axially flexible. For example, the output flexure can be made of a flexible material such as titanium. In one example, the output flexure 1326 can be made of a softer material than the Belleville spring 1328. For example, the output flexure 1326 can have a spring constant that is less than (e.g., 10%) the spring constant of the Belleville spring 1328. In this example, the Belleville spring 1328 provides an axial preload that is more dominant than the force applied to the clutch pad 1322 by the output flexure 1326. However, other configurations are also possible. The output flexure 1326 is configured to torsionally connect the robot member 1330 to the clutch pad 1322 while allowing its axial motion to accommodate wear and also allowing the Belleville spring 1328 to preload the clutch pad 1322 against the rigid gear 1318.

[0151] In one example, a restraint ring 1334 can be disposed between the pressure plate 1324 and the robot member 1330. The restraint ring 1334 has an open annular space in which the rigid gear 1318 and the clutch pads 1320 and 1322 are disposed and restrained. In one example, the restraint ring 1334 can be made of aluminum; however, other materials are also possible.

[0152] The radial array of fasteners or bolts, such as bolts 1335A and 1335B, can be configured to hold together the assembly including the pressure plate 1324, the restraint ring 1334, the output flexure 1326, and the robot member 1330. The clutch pads 1320 and 1322 and the rigid gear 1318 are squeezed between the output flexure 1326 and the pressure plate 1324 due to the axial preload applied by the Belleville spring 1328. As such, the clutch pads 1320 and 1322 and the rigid gear 1318 are also part of the assembly held together by the radial array of bolts including bolts 1335A and 1335B.

[0153] As described above, as the waveform generator 1312 rotates, the rigid gear 1318 rotates because the flexible gear 1314 is fixed. The rigid gear 1318 rotates at a reduced rotational speed relative to the waveform generator 1312, but can apply an amplified torque relative to the torque applied by the waveform generator 1312. As the rigid gear 1318 rotates, the clutch pads 1320 and 1322 frictionally coupled thereto also rotate, and the torque transmitted from the rigid gear 1318 to the clutch pads 1320 and 1322 is transmitted to the robot component 1330 via two paths. The first path includes transmitting the torque from the rigid gear 1318 through the clutch pads 1322 to the output flexure 1326, which is coupled to the robot component 1330 via a bolt array. The second path includes transmitting the torque from the rigid gear 1318 through the clutch pads 1320 to the pressure plate 1324, which is coupled to the robot component 1330 via a bolt array.

[0154] Crossed roller bearings 1336 may be mounted to the outer circumferential surface of the restraint ring 1334 between the inner surface of the housing 1302 and the restraint ring 1334. The crossed roller bearings 1336 facilitate rotation of the robotic component 1330 relative to the housing 1302 and may be configured to handle radial thrust and moment reaction loads applied to the robotic component 1330.

[0155] The system described above facilitates overload protection of the motor 1302 and the harmonic drive while allowing the reduction ratio of the harmonic drive to be reduced, and thereby reducing its moment of inertia. As an example, the motor 1302 may be rotated rapidly in an attempt to move the robotic member 1330 to a particular position. As the robotic member 1330 moves, it may hit or encounter unexpected or undetected objects. As a result, without an overload protection system, the motor 1302 may be forced to stop within a small period of time (e.g., 1 millisecond). A torque of up to four times the torque capacity of the harmonic drive may be applied to it to stop it. If the harmonic drive is designed to withstand or apply such high torques, the harmonic drive will be larger and exhibit a greater moment of inertia.

[0156] As another example, the robot may hit an object, such as the robot may fall from a certain height to the ground surface, and the impact may cause high torque to be applied to the harmonic drive, which may cause damage. In another example, the robot may be in an inactive state (e.g., power to the robot via a battery is turned off, a cable is broken, or a controller failure occurs). If an object hits the robot in this state, the robot's controller may not be able to obtain power and may therefore be unable to send signals to the electric safety components to protect the robot. In all of these examples, the harmonic drive and motor 1302 may experience high torque, which may cause damage to its components.

[0157] In having Figures 13A-13C In the case of the integrated overload protection system described, if the load torque on the robot component 1330 exceeds the torque limit set by the axial preload of the Belleville spring 1332, the rigid gear 1318 will slip relative to the clutch pads 1320 and 1322. In this way, the harmonic drive part (i.e., the rigid gear 1318) is disengaged from the robot component 1330 for a period of time and is thereby protected against high load torques. Further, when the rigid gear 1318 slides in relative to the clutch pads 1320 and 1322, the kinetic energy of the robot component 1330 is dissipated due to the friction between the rigid gear 1318 and the clutch pads 1320 and 1322. Once the load torque drops below the torque limit, the harmonic drive reengages the robot component 1330.

[0158] An advantage of the overload protection system is that the clutch pads 1320 and 1320 are integrated into the harmonic drive and engage with its components, namely the rigid gear 1318. This integration allows for a compact design, rather than adding a clutch system to the harmonic drive, which would require more longitudinal space.

[0159] Another advantage is that the output flexure 1326 is configured to allow the robotic component 1330 to reverse its direction of motion with zero backlash. Most robotic components, such as the robotic component 1330, operate in two directions. For example, if the robotic component 1330 is a leg of a robot, the motor 1302 can rotate in one direction to swing the leg in the corresponding direction, then stop the leg and rotate in the reverse direction to swing the leg in the opposite direction. In addition to the control of the force applied by the leg, the exact position control, velocity, and acceleration of the leg can depend on several factors including zero backlash when reversing the direction of motion.

[0160] If there is a gap, one of the two clutch pads 1320 and 1322 may engage the rigid gear 1318 when reversing the direction, while the other clutch pad may not engage. Thus, the engaged clutch pad may begin to slip relative to the rigid gear 1318, and after a period of time, the other clutch pad may start to be loaded, and the two clutch pads 1320 and 1322 will slide together relative to the rigid gear 1318.

[0161] Because of the flexibility of the Belleville spring 1328 and the output flexure 1326, they can accommodate axial movement of components of the drive system relative to each other. For example, they can accommodate wear in the clutch pads 1320 and 1322, axial movement of the robotic component 1330 relative to the harmonic drive, etc., without overstressing the components. Thus, the output flexure 1326 and the Belleville spring 1328 can compensate for manufacturing tolerances of the various components.

[0162] At the same time, the output flexure 1326 pushes against the clutch pad 1322 and keeps the clutch pads 1320 and 1322 in contact with the rigid gear 1318, thereby eliminating backlash. Therefore, the output flexure 1326 can ensure smooth movement of the robot member 1330 even if the motor 1302 and the rigid gear 1318 are stopped and then reversed in their rotation direction.

[0163] Further, the output flexure 1326 can cause the torque load to be shared equally between the two clutch pads 1320 and 1322. The force applied by the output flexure 1326 maintains the contact of the clutch pad 1322 against the rigid gear 1318. The same force applied by the output flexure 1326 further presses the clutch pad 1322 against the rigid gear 1318 and the clutch pad 1320 against the pressure plate 1324. In this way, the clutch pads 1320 and 1322 are equally stressed when the rigid gear 1318 rotates.

[0164] In some cases, grease or other lubricants may be applied to Figures 12A-13B Components of the harmonic drive unit shown or bearings in the drive system. Lubricants reduce wear and friction between the meshing components of the drive system. In these examples, seals (e.g., O-rings and 1338B) can be used to keep grease away from the clutch pads 1320 and 1322. In particular, O-ring 1338A can keep grease away from the interface between the clutch pad 1320 and the proximal end face of the rigid gear 1318 where the clutching occurs. And, O-ring 1338B can keep grease away from the interface between the clutch pad 1322 and the distal end face of the rigid gear 1318 where the clutching occurs. In this way, the grease does not affect the torque limit (i.e., the slip torque) determined at least in part by the elastic constant of the Belleville spring 1328.

[0165] However, in other exemplary embodiments, O-rings 1338A and 1338B may not be used. The axial preload applied by Belleville spring 1328 can then be adjusted, for example by selecting a Belleville spring with a different spring constant to accommodate the presence of grease. Changing the spring constant of the Belleville spring can adjust the performance of clutch pads 1320 and 1322 to operate at a reduced friction coefficient caused by grease.

[0166] As described above, when the waveform generator 1312 rotates with the shaft 1310 of the motor 1302, the rigid gear 1318 also rotates because the flexible gear 1314 is fixed. When the rigid gear 1318 rotates, the assembly including the clutch pads 1320-1322, the pressure plate 1324, and the restraint ring 1334 also rotates. The robot component 1330 also rotates via the radial bolt array (e.g., bolts 1335A-1335B). As long as the load torque applied to the robot component 1330 does not exceed the torque limit, the assembly and the robot component 1330 rotate with the rigid gear 1318. If the load torque exceeds the torque limit, the rigid gear 1318 slips relative to the clutch pads 1320 and 1320.

[0167] In the case of torque overload, the elliptical shape of the waveform generator 1312 will cause the rigid gear 1318 to also be distorted into an elliptical shape. When the torque drops below the torque limit, the clutch pads 1320 and 1322 reengage the rigid gear 1318 and can thereby maintain its elliptical shape. This distorted elliptical shape of the rigid gear 1318 will cause torque pulsation at the robot component 1330.

[0168] In order to prevent the rigid gear 1318 from being maintained in a distorted shape, the constraint bushing 1340 may be inserted between the outer circumferential surface of the rigid gear 1318 and the inner circumferential surface of the constraint ring 1334. The gap between the outer circumferential surface of the rigid gear 1318 and the inner circumferential surface of the constraint ring 1334 and the thickness of the constraint bushing 1340 are small. For example, the interference may be 1 / 1000 inch.

[0169] In some examples, the constraint bushing 1340 can be made of a plastic material, such as a polyetheretherketone (PEEK) material or other polymer material. The plasticity of the constraint bushing 1340 gives it a relatively low rigidity, thereby facilitating the constraint bushing 1340 to be inserted into the interference portion with a light press fit. This configuration accommodates manufacturing differences in the size and concentricity of the rigid gear 1318 and the constraint ring 1334.

[0170] During robot operation, the respective temperatures of constraint bushing 1340, rigid gear 1318, and constraint ring 1334 may rise. Rigid gear 1318 and constraint ring 1334 may expand and contract at different rates because they may be made of different materials with different coefficients of thermal expansion. However, the plastic material of constraint bushing 1340 may become softer and thereby accommodate any dimensional changes of rigid gear 1318 and constraint ring 1334 due to temperature changes.

[0171] Further, the constraint bushing 1340 couples the rigid gear 1318 and the constraint ring 1334 so that they move as a component. Thus, when the shape of the rigid gear 1318 changes (e.g., ovates) under torque load, the rigid gear 1318 and the constraint ring 1334 can be twisted together with the constraint bushing 1340. In this way, when the torque load drops below the torque limit, the rigid gear 1318, the constraint bushing 1340 and the constraint ring 1334 can rebound together to an undistorted shape. Also, because of the presence of the constraint bushing 1340 (compared to having a gap or clearance), the rigid gear 1318, the constraint bushing 1340 and the constraint ring 1334 can be less deformed. Thus, the presence of the constraint bushing 1340 can prevent torque pulsation.

[0172] Rigid gear 1318 and restraint ring 1334 may be made of different materials. For example, rigid gear 1318 may be made of cast iron, while restraint ring 1334 may be made of titanium. Allowing rigid gear 1318 to contact restraint ring 1334 may allow bonding and adhesion to form between them. Restraint bushing 1340 operates as an engagement member between rigid gear 1318 and restraint ring 1334 to prevent such bonding and adhesion while preventing torque pulsation as described above.

[0173] As above for Figures 12A-13C The components and configurations described are exemplary components and configurations and should not be considered limiting. Other components and configurations may be used. For example, instead of using two clutch pads, one clutch pad may be used. In another example, a clutch pad may be used on one side of the rigid gear 1318 and any type of friction material with exposed metal on the metal contact site may be used on the other side.

[0174] In the configuration described above, a clutch operation with overload protection occurs at the interface between the clutch pads 1320 and 1322 and the rigid gear 1318. In another exemplary embodiment, a clutch operation may occur at the interface between the clutch pads 1320 and the output flexure 1326 and the interface between the clutch pads 1322 and the pressure plate 1324. In this example, the clutch pads 1320 and 1320 may be integrated with the rigid gear 1318. In other words, the proximal and distal surfaces of the rigid gear may have friction materials disposed thereon. Further, in other examples, other components may be added between the rigid gear 1318 and the clutch pads 1320 and 1322. In another exemplary variation, the output flexure 1404 and the Belleville spring 1328 may be integrated into one flexible component. Also, this article uses an example, and in other embodiments, any other type of elastic or flexible, flexible element may be used.

[0175] Fig.14 An alternative configuration of a drive system for the robotic member 1400 is shown according to an exemplary embodiment. Fig.14 As shown, bolt ring 1402 replaces pressure plate 1324 and restraint ring 1334. In other words, pressure plate 1324 and restraint ring 1334 can be integrated into a single component, such as Fig.14 As shown in the bolt ring 1402.

[0176] The output flexure 1404 (which may perform similar operations to the output flexure 1326) is coupled to the robot member 1400 at the central region 1406 via an array of bolts including bolts such as bolt 1408. Compared to the bolts 1335A-1335B, for example Fig.14 Such bolts as the bolts 1410 in FIG. 14A couple the bolt ring 1402 to the robot component 1400 without coupling the output flexure 1402 thereto.

[0177] These variations are merely examples for purposes of illustration, and those skilled in the art will appreciate that other structures and other elements (eg, components, interfaces, sequences, and combinations of components) may be used instead, and that some elements may be omitted entirely, depending on the desired results.

[0178] c. Exemplary Motor-Controller Integration Configuration

[0179] An exemplary robot may include several joints to control the motion of respective components of the robot. As an example, a quadruped robot may have 17 joints that connect and control components of the robot (e.g., arms, legs, etc.). In some examples, many of these joints may have respective motors configured to move components of the robot. Each motor is controlled by a controller that receives several inputs (e.g., from sensors) and provides control signals to the motors accordingly to control the joints and components of the robot.

[0180] In one example, the controller may be placed at a central location on the robot, and wires may be connected between the controller and the various motors and sensors. This configuration may involve complex wiring and long wires, which may reduce the reliability of the robot and increase the likelihood of failure.

[0181] In other examples, each joint may have its own motor and controller for the motor. Integrating and co-locating the motor and its controller may improve the reliability of the robot. Such integration may reduce the complexity of the wiring configuration.

[0182] Disclosed herein are systems and devices with integrated motor and controller assemblies to reduce the complexity and increase the reliability of robots. In particular, the motor and its controller can be integrated into a compact package close to each other to facilitate sharing of sensors and thermal management components. Through the configurations disclosed herein, the number and length of wires are reduced, thereby enhancing the reliability of the robot by reducing potential failure points. These configurations can thereby reduce the likelihood of failure and downtime of the robot and reduce the maintenance cost of the robot.

[0183] Fig.15A An integrated motor controller assembly 1500 is shown according to an exemplary embodiment. As shown, the assembly 1500 includes a motor 1502 disposed in a housing 1504. The housing 1504 includes heat sink fins 1506 that are circumferentially spaced about the outer surface of the housing 1504 in a circular array.

[0184] The assembly 1500 includes a controller 1508, which may include one or more printed circuit boards (PCBs). For example, the controller 1508 may include a power stage PCB 1510 and a logic stage PCB 1512. The power stage PCB 1510 may, for example, include power electronics, which may include solid-state electronics configured for control and conversion of electrical power provided to the stator windings of the motor 1502. For example, the power stage PCB 1510 may include a plurality of field effect transistors (FETs).

[0185] The logic level PCB 1512 may include, for example, one or more microprocessors and data memory, which includes instructions to be executed by the one or more microprocessors to perform various control operations for the motor 1502. The power level PCB 1510 and the logic level PCB 1512 communicate with each other. Fig.15A In the exemplary embodiment shown, the power stage PCB 1510 and the logic stage PCB 1512 are juxtaposed or arranged on respective axially spaced planes. However, in other examples, they may be arranged in different configurations and in some exemplary components of the power stage PCB 1510 and the components of the logic stage PCB 1512 may be integrated into a single PCB.

[0186] The rotor of the motor 1502 is coupled to a shaft 1514 that transmits the rotational motion of the rotor to a transmission device such as a harmonic drive 1516. In one example, the shaft 1514 can be hollow and the magnet 1518 can be disposed at the proximal end thereof. As used herein, the term "proximal end" refers to the end of the shaft 1514 that is closer to the controller 1508, while the "distal end" of the shaft 1514 refers to the end that is coupled to the harmonic drive 1516.

[0187] As shown, shaft 1514 extends through power stage PCB 1510 such that magnet 1518 is disposed closer to and facing logic stage PCB 1512. Further, logic stage PCB 1512 may include a rotational position sensor 1520 (e.g., a magnetoresistive sensor or a Hall effect sensor) disposed thereon and facing magnet 1518.

[0188] The magnet 1518 may be magnetized along the diameter so that when the shaft 1514 and magnet 1518 coupled thereto rotate, the sensor 1520 provides information indicating the rotational position of the shaft 1514 to the controller 1508. This information is used by the controller 1508 to control the commutation of the motor 1502. With this configuration, the rotational position sensor 1520 of the motor 1502 is integrated into the motor controller 1508. This configuration is in contrast to other configurations in which the rotational position sensor of the motor is disposed closer to the motor and wires connect the sensor to the controller, thereby increasing the likelihood of wire damage and failure.

[0189] The assembly 1500 may further include another rotational position sensor or output encoder 1522 configured to provide information indicative of the rotational position of the robotic component 1524 to the logic level PCB 1512. For example, the output encoder 1522 may be coupled to a pressure plate 1526, which may be coupled to the robotic component 1524. By measuring the rotational position of the pressure plate 1526, the output encoder 1522 provides a measurement of the rotational position of the robotic component 1524.

[0190] In this manner, the controller 1508 receives information indicating the rotational position of the motor 1502 and the robotic member 1524. Thus, the controller 1508 can determine whether the rigid gear 1528 of the harmonic drive 1516 is due to the above-described rotational position of the motor 1502 and the robotic member 1524. Figure 13A-14 The assembly 1500 further includes a torque load cell or torque sensor 1530 configured to measure the torque load on the harmonic drive 1516 .

[0191] Fig. 15B According to an exemplary embodiment, the torque sensor 1530 and the output encoder 1522 are shown connected to the controller 1508. The wires from the torque sensor 1530 and the output encoder 1522 can be routed and combined at a connection 1532 fixed to the torque sensor 1530, which is fixed to the stator housing of the motor 1502. The wires can then be connected to a flexible PCB 1534, which can be configured to perform preliminary processing (e.g., signal amplification, filtering, etc.) on the signals from the torque sensor 1530 and the output encoder 1522.

[0192] Wires from the flexible PCB 1534 may then be routed through the housing 1504 and to one or more connectors 1536. The connectors 1536 may be configured to connect to corresponding connectors 1537 (e.g., to the power stage PCB 1510) via sealing grommets 1538. Fig.15D and 15G Through this construction, bringing the output encoder 1522 and the torque sensor 1530 close to the controller 1508 facilitates the integration and shortening of the wires, thereby improving the reliability of the robot.

[0193] like Figures 15A-15B The illustrated configuration may also be used to share thermal management components between the motor 1502 and the controller 1508. According to an exemplary embodiment, Fig. 15C shows thermal management of assembly 1500, and Fig.15D A bottom view of the power stage PCB 1510 is shown.

[0194] FET 1540 may be disposed on a surface of power stage PCB 1510 facing away from logic stage PCB 1512. Also, thermal sensor 1542 is disposed on the same surface of power stage PCB 1510 on which FET 1540 is disposed. Thermal interface material 1544 separates power stage PCB 1510 and components mounted thereon from ribs 1546 that extend radially inward from the inner circumferential surface of housing 1504. In other exemplary embodiments, any other thermal coupling surface or thermally conductive structure may be used in place of or in addition to ribs 1546. For example, instead of distinct ribs, a solid surface may be used. Other examples are also possible.

[0195] The thermal interface material 1544 can be a bendable, flexible material that compensates for height variations of components mounted on the power stage PCB 1510. The thermal interface material 1544 includes a thermally conductive material that can increase the contact thermal conductivity of the coupled solid surfaces to increase the efficiency of heat transfer. Rather than leaving a gap filled with air (which is a poor thermal conductor) between the power stage PCB 1510 and the ribs 1546, the thermal interface material 1544 is provided to enhance thermal efficiency and transfer. In particular, heat transfer between the power stage PCB 1510 and the ribs 1546 is enhanced.

[0196] Thermal interface material 1544 may include a silicon-based material or a non-silicon-based material and may take several forms. For example, thermal interface material 1544 may include a slurry or thermal grease, such as made from silicone oil filled with aluminum oxide, zinc oxide, or boron nitride. Thermal interface material 1544 may also use micronized or powdered silver. In some examples, thermal interface material 1544 may include glass fibers for reinforcement.

[0197] The ribs 1546 are also configured to provide a thermal path for heat generated by the motor 1502, and in particular by its stator windings. By this configuration, the controller 1508 and the motor 1502 share a common thermal management and dissipation structure. Fig.15D The arrows in show exemplary heat paths for both the motor 1502 and the controller 1508. Heat generated from the motor 1502 and the controller 1508 is conducted through the ribs 1546 to the fins 1506 disposed on the housing 1504.

[0198] The shroud 1548 surrounds the fan 1550, which, when activated, draws air and directs it toward the fins 1506. In this way, the fan 1550 can enhance heat dissipation at the fins 1506 and cool both the motor 1502 and the controller 1508.

[0199] The thermal sensor 1542 is placed on the same surface of the power stage PCB 1510 as described above with the FET 1540, and thereby provides information indicating the temperature of the other components of the controller 1508 and the FET 1540. The thermal sensor 1542 may also be in contact with or near the rib 1546. The thermal sensor 1542 may also thereby provide information indicating the temperature of the stator of the motor 1502 (which is near the rib 1546). With this configuration, both the motor 1502 and the controller 1508 share a common thermal sensor. The sensor information provided to the controller 1508 by the thermal sensor 1542 may be used to control when and at what speed the fan 1550 is operated.

[0200] Thermal sensor 1542 can also be used for safety monitoring of motor 1502 and harmonic drive 1516 (e.g. Fig.15A ). For example, thermal sensor 1542 may indicate that the stator temperature exceeds a critical temperature, which in turn may indicate that motor 1502 or harmonic drive 1516 is overloaded. Alternatively, high temperatures may indicate that a component of harmonic drive 1516 may be misaligned and should be maintained.

[0201] In this manner, the thermal sensor 1542 can indicate to the controller 1508 the status of the various components of the controller 1508 itself and the motor 1502. The controller 1508 can then determine whether to continue the joint operation or shut it down for safety reasons. Figures 15A-15D Integration of the motor 1502 and controller 1508 as shown allows for a common thermal sensor to be provided for both of them, thereby reducing the length and extent of wiring associated with thermal management.

[0202] If the motor 1502 and the controller 1508 each had their own thermal sensor, the number of sensors and wiring would be doubled for the robot. For a quadruped robot with 17 joints, the amount and range of wiring would increase greatly, thereby reducing the reliability of the robot as a whole. This integration achieves a reduction in the number of components and wiring complexity, which can enhance the overall reliability of the robot.

[0203] In some examples, such as Fig. 15C As shown, logic level stand-offs (e.g., stand-off 1551A) may be used to provide a consistent distance between logic level PCB 1512 and power level PCB 1510. These stand-offs may ensure that components of the two PCBs do not contact each other.

[0204] Further, power stage pillars (e.g., pillar 1551B) can be used to provide a consistent gap or distance between FET 1540 and rib 1546. FET 1540 can be "live" and thus can have a high voltage that can damage other components when they are conducting with it. The power stage pillars prevent FET 1540 from contacting any other components. Further, providing a consistent distance between FET 1540 and rib 1546 helps estimate the amount and thickness of thermal interface material 1544 to be placed between them.

[0205] In some examples, the motor 1502 can be a three-phase motor having three windings or phases spaced apart electrically at 120°. The stator of the motor 1502 can include 12 slot windings and can thus have 12 wires extending therefrom. The 12 wires can be arranged in several configurations, such as a delta, star, parallel, or series configuration. The configuration can affect the performance and torque output of the motor 1502.

[0206] Although 12 wires are led out of the stator, the number of wires is reduced to 3 or 6 wires after the wires are configured in a star, parallel or series configuration to be received at the controller 1508. In order to facilitate the connection of the 12 wires led out of the stator with the controller 1508, a phase circuit board 1552 can be provided therebetween. The phase circuit board 1552 operates as an intermediate or conversion circuit board between the stator of the motor 1502 and the controller 1508.

[0207] According to an exemplary embodiment, Fig.15E 12 wires are shown coming out of the stator 1554 of the motor 1502, and Fig.15F A phase circuit board 1552 is shown configured to engage with a stator 1554. The stator 1554 passes 12 winding wires, such as wires 1555A and 1555B. The phase circuit board 1552 is configured to receive the 12 wires from the stator 1554 and include the conductive wires therein so that the final connection forms the desired configuration of star, triangle, parallel or series. The phase circuit board 1552 then provides 3 or 6 pins, such as pins 1556A and 1556B, to the controller 1508 (i.e., to the power stage PCB 1510). With this configuration, the phase circuit board 1552 converts the wires from the stator 1554 into robust pins that are received at the connectors of the power stage PCB 1510. This configuration reduces wiring complexity and increases reliability, and increases the ability to repair the assembly 1500.

[0208] In some examples, the phase circuit board 1552 can be coupled (e.g., glued via any type of adhesive) to the stator 1554. To change the wiring configuration (e.g., from star to delta), the phase circuit board 1552 can be removed and a different phase circuit board that achieves the desired wiring configuration can be coupled to the stator 1554 without changing the stator 1554. In this way, minimal changes are performed on the stator 1554 and the risk of damaging the stator 1554 is reduced.

[0209] Similarly, no or minimal changes are performed on the controller 1508. The phase circuit board used for replacement will provide the same number of pins to the controller 1508. In this way, the risk of damage to the expensive controller 1508 is reduced.

[0210] Figure 15G An exploded view of assembly 1500 is shown according to an exemplary embodiment. Figure 15G The exploded view in FIG. 1 further illustrates the relationship and assembly order of the various components of assembly 1500. In one example, Figure 15G As shown, an electrical insulating sheet 1558 may be disposed between the phase circuit board 1552 and the housing 1504 to ensure electrical insulation therebetween.

[0211] As such, integrating motor 1502 and controller 1508 and sharing components allows for a reduction in the size and complexity of assembly 1500. Further, the likelihood of wire damage is reduced, and the reliability of assembly 1500 is increased. In the case where a robot may include many components similar to assembly 1500, the increased reliability can have a significant effect on the robot as a whole.

[0212] III. Conclusion

[0213] Structure described herein is only for the purpose of example. Thus, it will be appreciated by those skilled in the art that, according to the desired result, other structures and other elements (e.g., machines, interfaces, operations, sequences, and operation groupings, etc.) may be used instead, and some elements may be omitted completely. Further, many elements described as functional entities may be combined, and the functional entities may be implemented as discrete or distributed parts or associated with other parts, in any suitable combination and position.

[0214] Although various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and not limitation, with the actual scope being given by the claims that follow and the full range of equivalents defined by such claims. Also, the terminology used herein is intended to describe specific examples only and is not limiting.

Claims

1. A transmission device (1200) configured to be coupled to a motor (1300) and a component (1330), the transmission device (1200) comprising: An output member (1318) rotates with the member (1330); an intermediate member (1314) engaged with the output member (1318), the intermediate member (1314) being fixed to define an open annular space; an input member (1312) coupled to the motor (1300) and configured to rotate with the motor (1300), the input member (1312) being configured to engage a fixed intermediate member (1314) and rotate within the open annular space, and when the input member (1312) rotates, the output member (1318) rotates at a different speed relative to the input member (1312); a first pad (1320) coupled to a first surface of the output member (1318); and A flexible member (1328) is configured to apply an axial preload on the first and second pads (1320, 1322), the axial preload defining a torque limit representing a torque load on the member (1330) that causes the output member (1318) of the transmission (1200) to slip relative to the input member (1312).

2. The transmission device (1200) according to claim 1, wherein: The first pad (1320) is directly engaged with the first surface of the output member (1318).

3. The transmission (1200) of claim 1 or claim 2, further comprising a second pad (1322) coupled to a second surface of the output member (1318), the second surface being opposite to the first surface.

4. The transmission device (1200) according to claim 3, wherein: The second pad (1322) directly engages the second surface of the output member (1318).

5. The transmission device (1200) according to claim 1, wherein: When the output member (1318) of the transmission (1200) slips relative to the input member (1312), the output member (1318) slips relative to the first and second pads (1320, 1322).

6. The transmission device (1200) according to claim 1, wherein: The first pad (1320) is coupled to a pressure plate (1324), which is coupled to a member (1330).

7. The transmission device (1200) according to claim 6, wherein: The second pad (1322) is coupled to an output flexure member (1326), which is disposed between the second pad (1322) and the member (1330) and is rotatably fixed to the pressure plate (1324).

8. The transmission device (1200) according to claim 7, wherein: The flexible member (1328) is disposed between the member (1330) and the output flexure member (1326) and applies an axial preload on the first and second pads (1320, 1322) via the output flexure member (1326) and the pressure plate (1324).

9. The transmission device (1200) according to claim 7 or 8, wherein: One or more shims (1332) are disposed between the member (1330) and the flexible member (1328) to vary the axial preload on the first and second pads (1320, 1322) to vary the torque limit.

10. The transmission device (1200) according to claim 7 or 8, wherein: When the output member (1318) of the transmission (1200) slips relative to the input member (1312), the output member (1318) slips relative to the pressure plate (1324) and the output flexure member (1326).

11. The transmission (1200) of claim 1, further comprising a restraint ring (1334) coupled to the member (1330), the restraint ring (1334) defining the open annular space in which the output member (1318) is mounted.

12. The transmission device (1200) according to claim 11 further includes a restraint bushing (1340) installed between the restraint ring (1334) and the output member (1318), wherein the restraint bushing (1340) includes an outer peripheral surface engaged with the inner peripheral surface of the restraint ring (1334) and an inner peripheral surface engaged with the outer peripheral surface of the output member (1318).

13. The transmission device (1200) according to claim 1, wherein: The input member is elliptical and is configured so that the intermediate member (1314) deforms as the input member (1312) rotates, wherein the intermediate member (1314) is configured to have external teeth (1212) disposed on its outer peripheral surface, and wherein the output member (1318) is configured to have internal teeth (1214) disposed on its inner peripheral surface and engaged with the external teeth (1212) of the intermediate member (1314).

14. The transmission device (1200) according to claim 13 further includes a torque sensor (1316) mounted on the housing (1302) of the motor (1300), wherein the fixed intermediate member (1314) includes a thin-walled cylinder, wherein the external teeth (1212) are circumferentially formed on a first portion of the outer surface of the thin-walled cylinder, and wherein a second portion of the thin-walled cylinder is connected to the torque sensor (1316).

15. The transmission device (1200) according to claim 1, wherein: The flexible member (1328) comprises a Belleville spring.

16. A robot (300), comprising: a motor (1300) disposed at a joint (403) configured to control movement of a member (1330) of the robot (300); and A transmission device (1200) according to any one of claims 1-15.

17. A transmission system comprising: Transmission device, including: an input member coupled to the motor and configured to rotate with the motor, output artifacts, and a fixed intermediate member engaging the output member, the input member being configured to engage the fixed intermediate member and rotate within an open annular space defined by the fixed intermediate member, and the output member rotates at a different speed when the input member rotates; a pad frictionally coupled to a side surface of an output member of the transmission; a spring configured to apply an axial preload on the pad, the axial preload defining a torque limit representing a torque load that causes an output member of the transmission to slip relative to the pad; and An output flexure member is disposed between and engaged with the pad and spring, wherein the output flexure member is torsionally rigid and axially flexible.

18. The system of claim 17, wherein: The pad includes a first pad, and wherein the system further includes a second pad frictionally coupled to a proximal side surface of the output member, and wherein the first pad is frictionally coupled to a distal side surface of the output member of the transmission.

19. The system of claim 18, wherein: The second pad is coupled to the pressure plate.

20. The system of claim 17, further comprising a restraint ring defining an open annular space in which an output member of the transmission is mounted.

21. The system of claim 20 further comprising a restraint bushing mounted between the restraint ring and the output member of the transmission, the restraint bushing comprising an outer circumferential surface engaging the inner circumferential surface of the restraint ring and an inner circumferential surface engaging the outer circumferential surface of the output member of the transmission.

22. The system of claim 17, further comprising an O-ring mounted within a second annular space defined by the pad.

23. The system of claim 17, wherein: The input member is oval and configured such that the intermediate member deforms as the input member rotates; The fixed intermediate member includes external teeth disposed on an outer peripheral surface of the intermediate member; and The output member includes internal teeth disposed on an inner peripheral surface of the output member, the internal teeth being configured to engage the external teeth of the intermediate member.

24. A transmission assembly comprising: Transmission device, including: an input member coupled to the motor and configured to rotate with the motor, output artifacts, and a fixed intermediate member engaging the output member, the input member being configured to engage the fixed intermediate member and rotate within an open annular space defined by the fixed intermediate member, and the output member rotates at a different speed when the input member rotates; a first pad frictionally coupled to two distal side surfaces of the output member; a second pad frictionally coupled to the proximal side surface of the rigid gear; a flexible member configured to apply an axial preload on the first and second pads, the axial preload defining a torque limit, and when the torque load satisfies the torque limit, the output member slips relative to at least one of the first or second pads; and The output flexible member is disposed between and coupled to the first pad and the flexible member.

25. The assembly of claim 24, wherein: The transmission comprises a harmonic drive, and wherein the input comprises a waveform generator, the intermediate member comprises a flexible gear, and the output member comprises a rigid gear.

26. The assembly of claim 24, wherein: The second pad is coupled to the pressure plate.

27. The assembly of claim 25, further comprising a restraint ring defining an open annular space, wherein the output member and first and second pads frictionally coupled to the output member are mounted within the open annular space.

28. The assembly of claim 27, further comprising a crossed roller bearing mounted between an outer peripheral surface of the restraining ring and an inner surface of the housing of the motor.

29. The assembly of claim 28, further comprising a restraint bushing mounted between the restraint ring and the rigid gear, the restraint bushing comprising an outer peripheral surface engaging the inner peripheral surface of the restraint ring and an inner peripheral surface engaging the outer peripheral surface of the rigid gear.

30. The assembly of claim 28, wherein: The first pad defines a first open annular space, the second pad defines a second open annular space, and the assembly further comprises: a first O-ring mounted within a first open annular space defined by the first gasket; and A second O-ring is mounted in a second open annular space defined by the second gasket.

31. The assembly of claim 28, wherein: The intermediate member includes a thin-walled cylinder having external teeth formed circumferentially on a portion of an outer surface of the thin-walled cylinder, and the assembly further includes a torque sensor mounted on a housing of the motor and coupled to a portion of the thin-walled cylinder.

32. The assembly of claim 28, wherein: The flexible member includes a Belleville spring.

33. A robot comprising: a motor disposed at a joint of a leg of the robot, the motor being configured to control movement of the leg of the robot; a transmission device including an input member coupled to a motor and configured to rotate with the motor, an output member, and a fixed intermediate member engaging the output member, the input member being configured to engage the fixed intermediate member and rotate within an open annular space defined by the fixed intermediate member, and the output member rotating at a different speed when the input member rotates; a pad frictionally coupled to a side surface of an output member of the transmission and coupled to a leg of the robot; a spring configured to apply an axial preload on the pad, the axial preload defining a torque limit representing a torque load on the leg of the robot that causes an output member of the transmission to slip relative to the pad; and An output flexure member is disposed between and engaged with the pad and the spring, wherein the output flexure member is torsionally rigid and axially flexible, and wherein the output flexure member is coupled to a leg of the robot.

34. The robot according to claim 33, wherein: The joints correspond to the hip joints of the robot's legs.

35. The robot of claim 34, further comprising a housing located at a hip joint of a leg of the robot, wherein the motor is disposed within the housing.

36. The robot according to claim 33, wherein: The robot includes a quadruped robot.

37. The robot according to claim 33, wherein: The robot comprises a bipedal robot.

38. The robot of claim 33, further comprising a second pad frictionally coupled to a proximal side surface of the output member, and wherein the pad is frictionally coupled to a distal side surface of the output member of the transmission.

39. The robot according to claim 38, wherein: The second pad is coupled to a pressure plate coupled to a leg of the robot.

40. The robot of claim 33, further comprising a restraint ring coupled to a leg of the robot, the restraint ring defining the open annular space in which the output member of the transmission is mounted.

41. The robot according to claim 40 further includes a constraint bushing installed between the constraint ring and the output member of the transmission device, and the constraint bushing includes an outer peripheral surface engaged with the inner peripheral surface of the constraint ring and an inner peripheral surface engaged with the outer peripheral surface of the output member of the transmission device.

42. The robot of claim 33, further comprising an o-ring mounted within the second annular space defined by the pad.

43. The robot of claim 33, wherein: The input member is oval and configured such that the intermediate member deforms as the input member rotates; The fixed intermediate member includes external teeth disposed on an outer peripheral surface of the intermediate member; and The output member includes internal teeth disposed on an inner peripheral surface of the output member, the internal teeth being configured to engage the external teeth of the intermediate member.

44. An assembly comprising: a motor disposed at a hip joint of a leg of the robot, the motor being configured to control movement of the leg of the robot; a harmonic drive including a waveform generator coupled to the motor and configured to rotate with the motor, a flexible gear and a rigid gear, and when the waveform generator rotates, the flexible gear is fixed and the rigid gear rotates at a different speed with the waveform generator; a first pad frictionally coupled to a distal side surface of the rigid gear and to a leg of the robot; a second pad frictionally coupled to the proximal side surface of the rigid gear; a flexible member configured to apply an axial preload on the first and second pads, the axial preload defining a torque limit, and when a torque load on the leg of the robot satisfies the torque limit, the rigid gear slips relative to at least one of the first or second pads; and An output flexure member is disposed between and coupled to the first pad and the flexible member, the output flexure member being coupled to a leg of the robot.

45. The assembly of claim 44, wherein the robot comprises a quadruped robot having four legs, and wherein the leg comprises one of the four legs of the quadruped robot.

46. ​​The assembly of claim 44, wherein the robot comprises a bipedal robot having two legs, and wherein the leg comprises one of the two legs of the bipedal robot.

47. The assembly of claim 44, wherein: The second pad is connected to a pressure plate, which is connected to the leg of the robot.

48. The assembly of claim 47, further comprising a restraint ring coupled to the leg of the robot, the restraint ring defining an open annular space, the rigid gear and the first and second pads frictionally coupled to the rigid gear being mounted within the open annular space, the pressure plate being coupled to the leg of the robot via a radial array of bolts coupling the pressure plate to the restraint ring.

49. The assembly of claim 48, further comprising a crossed roller bearing mounted between an outer peripheral surface of the confinement ring and an inner surface of the housing of the motor.

50. The assembly of claim 44, further comprising a restraint bushing mounted between the restraint ring and the rigid gear, the restraint bushing comprising an outer peripheral surface engaged with the inner peripheral surface of the restraint ring and an inner peripheral surface engaged with the outer peripheral surface of the rigid gear.

51. The assembly of claim 44, wherein: The first pad defines a first open annular space, the second pad defines a second open annular space, and the assembly further comprises: a first O-ring mounted within a first open annular space defined by the first gasket; and A second O-ring is mounted in a second open annular space defined by the second gasket.

52. The assembly of claim 44, wherein: The flexible gear includes a thin-walled cylinder with external teeth formed circumferentially on a portion of an outer surface of the thin-walled cylinder, and the assembly further includes a torque sensor mounted on the housing of the motor and coupled to a portion of the thin-walled cylinder.

53. The assembly of claim 44, wherein: The flexible member includes a Bellevill spring.

54. An assembly comprising: a motor disposed at a hip joint of a leg of the robot, the motor being configured to control movement of the leg of the robot; The harmonic drive unit includes: a waveform generator coupled to the motor and configured to rotate with the motor; Flexible gears; and a rigid gear, and when the waveform generator rotates, the flexible gear is fixed while the rigid gear rotates at a different speed with the waveform generator, wherein the flexible gear includes a thin-walled cylinder, wherein external teeth are circumferentially formed on a portion of an outer surface of the thin-walled cylinder; A torque sensor is mounted on the motor housing and coupled to a portion of the thin-walled cylinder; a first pad frictionally coupled to a distal side surface of the rigid gear and to a leg of the robot; a second pad frictionally coupled to the proximal side surface of the rigid gear; and The flexible member is configured to apply an axial preload on the first and second pads, the axial preload defining a torque limit, and when the torque load on the leg of the robot satisfies the torque limit, the rigid gear slips relative to at least one of the first or second pads.

55. A drive system comprising: Transmission device, including: an input member coupled to the motor and configured to rotate with the motor, output artifacts, and a fixed intermediate member engaging the output member, the input member being configured to engage the fixed intermediate member and rotate within an open annular space defined by the fixed intermediate member, and the output member rotating at a different speed when the input member rotates; one or more pads frictionally coupled to the output member; a flexible member configured to apply an axial preload on the one or more pads, the axial preload defining a torque limit; a restraining ring defining an open annular space in which the output member is mounted; and The restraint bushing is installed between the restraint ring and the output member. Wherein when the torque load on the output member satisfies the torque limit, the output member slips relative to at least one of the one or more pads.

56. The system of claim 55, wherein: The transmission comprises a harmonic drive, and wherein the input member comprises a waveform generator, the intermediate member comprises a flexible gear, and the output member comprises a rigid gear.

57. The system of claim 55, wherein: Also included is a torque sensor mounted on the housing of the motor and coupled to the output member, the torque sensor being used to measure the torque load on the output member.

58. The system of claim 55, wherein the one or more pads comprise: a first pad frictionally coupled to both distal side surfaces of the output member; and A second pad is frictionally coupled to the proximal side surface of the output member.

59. The system of claim 58, wherein: The second pad is connected to the pressure plate.

60. The system of claim 58, further comprising an O-ring mounted within a second annular space defined by the first gasket or the second gasket.

61. The system of claim 55, wherein: The constraining bushing includes an outer peripheral surface engaged with the inner peripheral surface of the constraining ring and an inner peripheral surface engaged with the outer peripheral surface of the rigid gear.

62. An assembly comprising: a motor disposed at a hip joint of a leg of the robot, the motor being configured to control movement of the leg of the robot; Transmission device, including: an input member coupled to the motor and configured to rotate with the motor, output artifacts, and a fixed intermediate member engaging the output member, the input member being configured to engage the fixed intermediate member and rotate within an open annular space defined by the fixed intermediate member, and the output member rotating at a different speed when the input member rotates; a first pad frictionally coupled to two distal side surfaces of the output member; a second pad frictionally coupled to the proximal side surface of the output member; a flexible member configured to apply an axial preload on the first and second pads, the axial preload defining a torque limit; a restraining ring defining a first open annular space in which the output member and first and second pads frictionally coupled to the output member are mounted; and The restraint bushing is installed between the restraint ring and the output member. Wherein when the torque load on the output member satisfies the torque limit, the output member slips relative to at least one of the first or second pads.

63. The assembly of claim 62 further comprising a crossed roller bearing mounted between an outer peripheral surface of the confinement ring and an inner surface of the housing of the motor.

64. The assembly of claim 63, wherein: The constraining bushing includes an outer peripheral surface engaged with the inner peripheral surface of the constraining ring and an inner peripheral surface engaged with the outer peripheral surface of the output member.

65. The assembly of claim 63, wherein: The first pad defines a second open annular space, the second pad defines a third open annular space, and the assembly further comprises: a first O-ring mounted within a second open annular space defined by the first gasket; and A second O-ring is mounted in a third open annular space defined by the second gasket.

66. The assembly of claim 62, wherein: The flexible member includes a Bellevill spring.

67. A robot comprising: a motor disposed at the joint, the motor being configured to control movement of a member of the robot; Harmonic drive unit, including: a waveform generator coupled to the motor and configured to rotate with the motor; Flexible gears; and Rigid gears, wherein, when the waveform generator rotates, the flexible gear rotates fixedly, while the rigid gear rotates at a speed different from that of the waveform generator; one or more pads frictionally coupled to the rigid gear and the robot member; a flexible member configured to apply an axial preload on the one or more pads, the axial preload defining a torque limit; a constraining ring coupled to the member of the robot, the constraining ring defining an open annular space in which the rigid gear is mounted; and The restraint bushing is installed between the restraint ring and the rigid gear. Wherein when the torque load on the component of the robot satisfies the torque limit, the rigid gear slips relative to at least one of the one or more pads.

68. The robot according to claim 67, wherein: Also included is a torque sensor mounted on the housing of the motor and coupled to the rigid gear, the torque sensor being configured to measure a torque load on a member of the robot.

69. The robot according to claim 67, wherein: The members of the robot correspond to the legs of the robot.

70. The robot according to claim 69, wherein: The joints correspond to the hip joints of the robot's legs.

71. The robot of claim 67, wherein said one or more pads comprise: a first pad frictionally coupled to a distal side surface of the rigid gear and a member of the robot; and A second pad is frictionally coupled to the proximal side surface of the rigid gear.

72. The robot according to claim 71, wherein: The second pad is coupled to a pressure plate that is coupled to a member of the robot.

73. The robot of claim 71, further comprising an O-ring mounted within a second annular space defined by the first pad or the second pad.

74. The robot according to claim 67, wherein: The constraining bushing includes an outer peripheral surface engaged with the inner peripheral surface of the constraining ring and an inner peripheral surface engaged with the outer peripheral surface of the rigid gear.

75. The robot according to claim 67, wherein: The robot comprises a bipedal robot.

76. The robot according to claim 67, wherein: The robot includes a quadruped robot.

77. An assembly comprising: a motor disposed at a hip joint of a leg of the robot, the motor being configured to control movement of the leg of the robot; Harmonic drive unit, including: a waveform generator coupled to the motor and configured to rotate with the motor; Flexible gears; and Rigid gears, wherein, when the waveform generator rotates, the flexible gear rotates fixedly, while the rigid gear rotates at a speed different from that of the waveform generator; a first pad frictionally coupled to a distal side surface of the rigid gear and to a leg of the robot; a second pad frictionally coupled to the proximal side surface of the rigid gear; a flexible member configured to apply an axial preload on the first and second pads, the axial preload defining a torque limit; a restraint ring coupled to the leg of the robot, the restraint ring defining a first open annular space, the rigid gear and first and second pads frictionally coupled to the rigid gear being mounted within the first open annular space; and The restraint bushing is installed between the restraint ring and the rigid gear. Wherein, when the torque load on the leg of the robot satisfies the torque limit, the rigid gear slips relative to at least one of the first or second pads.

78. The assembly of claim 77, wherein the robot comprises a quadruped robot having four legs, and wherein the leg comprises one of the four legs of the quadruped robot.

79. The assembly of claim 77, wherein: The second pad is coupled to a pressure plate coupled to a leg of the robot.

80. The assembly of claim 79, wherein: The pressure plate is coupled to the leg of the robot via a radial array of bolts that couple the pressure plate to the restraining ring.

81. The assembly of claim 80, further comprising a crossed roller bearing mounted between an outer peripheral surface of the confinement ring and an inner surface of the housing of the motor.

82. The assembly of claim 77, wherein: The constraining bushing includes an outer peripheral surface engaged with the inner peripheral surface of the constraining ring and an inner peripheral surface engaged with the outer peripheral surface of the rigid gear.

83. The assembly of claim 77, wherein: The first pad defines a second open annular space, the second pad defines a third open annular space, and the assembly further comprises: a first O-ring mounted within a second open annular space defined by the first gasket; and A second O-ring is mounted in a third open annular space defined by the second gasket.

84. The assembly of claim 77, wherein: The flexible gear includes a thin-walled cylinder with external teeth formed circumferentially on a portion of an outer surface of the thin-walled cylinder, and the assembly further includes a torque sensor mounted on the housing of the motor and coupled to a portion of the thin-walled cylinder.

85. The assembly of claim 77, wherein: The flexible member includes a Bellevill spring.

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