Low-impedance actuation device using magnetorheological fluid clutch device

Abstract

A magnetorheological (MR) actuator apparatus includes two or more MR actuator units. Each MR actuator unit may include: a motor; an MR fluid clutch device operably coupled to the motor to receive torque from the motor, the MR fluid clutch device operable to generate a variable torque transmission when subjected to a magnetic field. An output member is provided; and a transmission device operably coupling at least two MR actuator units to the output member, for the output member to receive torque from the MR actuator units. A controller is provided for controlling the two or more MR actuator units to drive the output member, the controller driving the output member in at least an antagonistic mode, wherein the MR actuator units transmit torque to the output member in opposite directions. A cooperative mode may be provided to combine the torques of the two or more MR actuator units on the output member in a common direction.

Description

Technical Field

[0001] The present application relates generally to the field of actuators, robotic joints, haptic devices, or power systems, and more particularly to actuators, robotic joints, haptic devices, or power systems using magnetorheological (MR) fluid clutch devices. Background Art

[0002] An actuator is a device used to generate a controllable force or torque on a system. Typical applications of actuators are found in haptic systems or robotics. Haptic systems involve physical contact between the actuator and the human user.

[0003] A robot is a device capable of manipulating objects or performing tasks using a series of rigid links or members interconnected via joints or actuated robotic joints. Typically, each joint represents a degree of freedom (DOF) and is controlled by one or more actuators. An end effector is a specialized link designed to perform a specific task, such as grasping a work tool or object.

[0004] Collaborative robots are robots designed to operate in close proximity to humans, and may even be designed to work alongside or assist humans while they perform tasks. A typical collaborative robot is a robotic arm with multiple interconnected robotic joints that enable movement. Each robotic joint has an output flange or shaft that can be connected to another robotic joint and a joint motor configured to rotate the output flange or shaft. The robotic joints can be connected directly together, or a connecting element can be provided between the two robotic joints.

[0005] Many robots have been introduced in recent years. Typically, robots use electric motors to actuate joints, although several other actuation technologies, such as hydraulic or pneumatic actuation, may also be used. This type of actuator can have relatively low force / position / velocity bandwidth and high impedance, which can cause user discomfort if the robot comes into direct contact with it. This discomfort often disrupts device functionality, limits interaction with humans or the environment, and reduces human interest in collaborating with the device.

[0006] Collaborative robots typically use motor / generator units to power their joints. The energy required for the actuators can be generated using internal combustion engines, turbines, hydraulic pumps, pneumatic turbines, or any other power source. Robots can also include one or more auxiliary power sources. For simplicity, any power source will be referred to as an auxiliary power source below. Some robots use mechanical (e.g., gears, connecting rods), hydraulic, or pneumatic transmission to route power to the joints.

[0007] Electric motors are most commonly used because they offer higher bandwidth than other actuator types. While high dynamic response is sought, the most common form of electromechanical actuation is found in DC-driven motors, which are too heavy for robotic joints. By setting a reduction ratio between the motor and the mechanical linkage, device weight can be significantly reduced. Indeed, for a given torque output, when coupled to a speed reducer (e.g., a gearbox), electromechanical actuators are lighter and less expensive than DC-driven solutions. However, their higher output inertia, friction, and backlash can reduce their dynamic performance.

[0008] They may not have the same bandwidth. A preferred embodiment is a robot in which a single electric motor is combined with a speed reducer (such as a harmonic drive gearbox) to provide a higher torque-density actuator. The bandwidth of this actuator is relatively lower than the bandwidth of the electric motor or the bandwidth of the motor of equivalent torque. The torque required to drive the robot backward may also be higher due to the friction of the gear system and the inertia reflected by the motor and gearbox.

[0009] If a user engages the robot and moves faster than the maximum speed of the actuator, they will reverse the force applied to the robot. Due to the low back-driveability, this situation can cause injury or discomfort to the user. Furthermore, due to its low bandwidth and high inertia, the robot is difficult to control, causing the user to feel the engagement and disengagement of the auxiliary power source. The low bandwidth of the power system can be caused by the high inertia of components that oppose changes in the system's speed, as well as friction and backlash in the system. When the user input speed changes, the user can foresee or feel the high inertia of the system, which can become cumbersome or dangerous. Systems with low bandwidth (i.e., with a lower response frequency than humans) may not adapt quickly enough to human muscle dynamics, resulting in the user feeling connected to a mechanical device that causes adaptation delays. This discomfort can arise from the fact that the mechanical system speed cannot keep up with the user's input speed, resulting in sticky or unnatural movements. Higher bandwidth, i.e., greater responsiveness, will make the robot more transparent to the user. For example, if someone wants a device to apply assistance proportional to the force applied by the user to create the illusion of easily moving a load, but the system has low bandwidth, this assistance may not adapt quickly enough and create a delay in applying the force that the user may feel. In the event of an unexpected collision with the user, a system with low bandwidth and high inertia may not adapt quickly enough, causing injury to the user. Typically, the bandwidth of an actuator can decrease due to inertial effects. For this reason, as inertia increases, the actuator may lose its ability to adapt to changes in human position and become dangerous for human interaction.

[0010] For controllability reasons, new technologies are needed to match the impedance of the auxiliary device to the impedance of the human or the environment. In devices where the operation of the auxiliary actuator involves a human or the environment and smooth movement is sought, the technology used should have a bandwidth that is even higher than the bandwidth of the human or the auxiliary device. The higher the bandwidth of the system in contact with the human and the lower the inertia, the more transparent the system is to the human and the more natural it feels. When there is an unpredictable source of contact with the robot, the bandwidth of the auxiliary power system needs to match or exceed the bandwidth of the source, otherwise the controllability of the system is not optimal. In addition, the actuators located at the joints of the robot that assists the human may need to be physically or programmed to be compliant and easy to drive back in order to not be damaged or to operate as expected. Systems in contact with the human body or the environment need to be compliant or drive back in order not to expose the human to unexpected forces or accelerations that could harm the human or damage the actuator.

[0011] Because they combine human power with an additional source of power to assist the human, other types of devices or equipment are recognized as providing human assistance similar to robots. A good example is a prosthesis or exoskeleton. In a prosthesis, a human is connected to a device that replaces a lost human limb. To achieve smoother movement control, new technologies are needed that allow the system's admittance to match or exceed that of the human body. Using this new technology, the device can also be paired with sensors that help identify the required human power or movement and adjust the actions of the prosthesis or exoskeleton to move in harmony with the human body.

[0012] Likewise, haptic devices or equipment are identified as providing human assistance by applying forces to the human body. Good examples of this are medical simulator arms that provide sensations from the virtual world or active sidesticks in aircraft that provide information to pilots about the aircraft's safe flight envelope. In this application, the human is connected to the device. Summary of the Invention

[0013] An object of the present disclosure is to provide a collaborative robotic device, such as a collaborative robot, haptic device, prosthesis, orthosis, or exoskeleton, that employs MR fluid actuation.

[0014] It is also an object of the present disclosure to provide an actuator or cooperating device having a plurality of MR fluid actuators.

[0015] Another object of the present disclosure is to provide an actuation device with an antagonist MR fluid actuator to reduce the induced torque generated by the robot joint to the human by actively compensating for parasitic effects (backlash, friction, viscosity).

[0016] It is an additional object of the present disclosure to provide an actuation apparatus having multiple MR fluid actuators selectively actuated by different MR fluid clutch devices to create a multiple degree of freedom actuation apparatus.

[0017] It is another object of the present disclosure to provide a cooperative device with an MR fluid actuator device that aims to reduce the inertia reflected by the device and convert the output of a low bandwidth power source to a high frequency band response.

[0018] In a first aspect of the present disclosure, a magnetorheological (MR) actuator apparatus is provided, comprising: at least two MR actuator units, each MR actuator unit including at least one motor; an MR fluid clutch device operatively coupled to the motor to receive torque from the motor, the MR fluid clutch device being operable to generate a variable torque transmission amount when passing through a magnetic field; an output member; a transmission device operatively coupling the at least two MR actuator units to the output member so that the output member receives torque from the at least two MR actuator units; and a controller for controlling the at least two MR actuator units to drive the output member, the controller driving the output member in at least an antagonistic mode, wherein the at least two MR actuator units transmit torque to the output member in opposite directions.

[0019] Further according to the first aspect, for example, in each MR actuator unit, the motor is bidirectional, and wherein the controller drives the output member in a coordinated mode, wherein at least two MR actuator units transmit torque to the output member in a common direction.

[0020] Still further, according to the first aspect, for example, for at least one MR actuator unit of the at least two MR actuator units, at least one speed reduction mechanism is located between the bidirectional motor and the MR fluid clutch device output member.

[0021] Still further, according to the first aspect, for example, for at least one MR actuator unit of the at least two MR actuator units, the transmission device has at least one speed reduction mechanism located between the MR fluid clutch device and the output member.

[0022] Still further, according to the first aspect, for example, for at least one MR actuator unit of the at least two MR actuator units, the transmission includes a spiral bevel gear coupled to the output member.

[0023] Still further, according to the first aspect, for example, the rotation axis of the spiral bevel gear is parallel to the rotation axis of the MR fluid clutch device.

[0024] Still further, according to the first aspect, for example, the spiral bevel gear is a hypoid gear or a spherical gear.

[0025] Still further, according to the first aspect, for example, the output member is a crown gear.

[0026] Still further, according to the first aspect, for example, there are at least three of the two MR actuator units.

[0027] Still further, according to the first aspect, the controller drives the output member in an antagonistic mode by, for example, causing two MR actuator units to transmit torque to the output member in a common direction and causing a third MR actuator unit to transmit torque to the output member in a direction opposite to the directions of the two MR actuator units.

[0028] According to a second aspect of the present disclosure, a system for driving an output member of a magnetorheological (MR) actuator device having at least two MR actuator units is provided, the system comprising: a processing unit; a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit; controlling the at least two MR actuator units to transmit torque to the common output member in a cooperative mode in a common direction; and controlling the at least two MR actuator units to transmit torque to the common output member in an antagonistic mode in opposite directions.

[0029] Further according to the second aspect, for example, controlling the at least two MR actuator units in the cooperative mode includes controlling slippage of at least one MR fluid clutch device.

[0030] Still further, according to the second aspect, for example, controlling the at least two MR actuator units in the antagonistic mode includes controlling slippage of at least one MR fluid clutch device.

[0031] Still further, according to the second aspect, for example, three MR fluid actuator units are provided, and controlling the MR actuator units in the antagonistic mode includes: controlling two MR actuator units to transmit torque to the output member in a common direction; and controlling the third MR actuator unit to transmit torque to the output member in a direction opposite to the directions of the two MR actuator units.

[0032] Still further, according to the second aspect, for example, the at least two MR actuator units are as described above.

[0033] According to a third aspect of the present disclosure, a single-degree-of-freedom actuation system is provided, comprising: at least two MR fluid clutch devices and at least two power sources; a first interface adapted to be fixed to a portion; a second interface adapted to be fixed to a second movable portion; at least one joint disposed between the first interface and the second interface with at least one degree of freedom; the at least two MR fluid clutch devices operable to generate a variable amount of torque transmission when passing through a magnetic field; and a transmission device coupling the MR fluid clutch devices to the actuation system; wherein the at least two MR fluid clutch devices can be independently controlled to act in opposing directions or in the same direction.

[0034] Further, according to the third aspect, for example, each MR fluid clutch device is connected to its own independent power source.

[0035] Still further, according to the third aspect, for example, the force generated by the MR fluid actuators can be added from one MR fluid actuator to another MR fluid actuator.

[0036] Still further, according to the third aspect, for example, the forces generated by the MR fluid actuator may be antagonistically applied in opposite directions.

[0037] Still further, according to the third aspect, for example, at least one MR fluid actuator is equipped with a brake.

[0038] Still further, according to the third aspect, for example, the mechanism is equipped with an independent brake.

[0039] Still further, according to the third aspect, for example, the power source is connected to the plurality of MR clutch devices.

[0040] Still further, according to a third aspect, for example, the actuation system has a biasing member that applies a force in a single direction.

[0041] Still further, according to the third aspect, for example, the actuation system is a rotary joint.

[0042] Still further, according to the third aspect, for example, the actuation system is a translation joint.

[0043] Still further, according to the third aspect, for example, the actuation system combines rotational and translational movement.

[0044] According to a fourth aspect of the present disclosure, a multi-degree-of-freedom actuator is provided, comprising: at least three MR fluid clutch devices and at least three power sources; a first interface adapted to be fixed to a portion; a second interface adapted to be fixed to a second movable portion; at least one joint disposed between the first interface and the second interface with at least two degrees of freedom; the at least three MR fluid clutch devices operable to generate a variable amount of torque transmission when passing through a magnetic field; and a transmission device coupling the MR fluid actuator unit to an actuation system; wherein the at least three MR fluid clutch devices can be independently controlled to generate a vector in a desired direction.

[0045] Further, according to the fourth aspect, for example, each MR fluid clutch device is connected to its own independent power source.

[0046] Still further, according to the fourth aspect, for example, the force generated by the MR fluid clutch devices may be added from one MR fluid clutch device to another MR fluid clutch device.

[0047] According to a fifth aspect of the present disclosure, a system for driving an output member of a magnetorheological (MR) actuator device having at least two MR actuator units that respectively output a maximum torque T1 and a torque T2 is provided, the system comprising: a processing unit; a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit; controlling the at least two MR actuator units to transmit torque to a common output member in a cooperative mode in a common direction, wherein the torque of the common output member in the cooperative mode is greater than the maximum torque T1 or the maximum torque T2; and controlling the at least two MR actuator units to transmit torque to the common output member in an antagonistic mode in opposite directions, wherein the torque of the common output member in the antagonistic mode is at most equal to the maximum torque T1 or the maximum torque T2.

[0048] Further according to the fifth aspect, for example, controlling the at least two MR actuator units in the cooperative mode includes controlling slippage of at least one MR fluid clutch device.

[0049] Still further, according to the fifth aspect, for example, controlling the at least two MR actuator units in the antagonistic mode includes controlling slippage of at least one MR fluid clutch device.

[0050] Still further, according to the fifth aspect, for example, controlling the at least two MR actuator units to transmit torque in the cooperative mode includes controlling the at least two MR actuator units to transmit torque at a common output member to be a sum of the maximum torque T1 or the maximum torque T2.

[0051] Still further, according to the fifth aspect, for example, there are three MR fluid actuator units, and the third MR fluid actuator unit outputs a maximum torque T3, and controlling the MR actuator units in the antagonistic mode includes: controlling the two MR actuator units to transmit torque to the output member in a common direction; and controlling the third MR actuator unit to transmit torque to the output member in a direction opposite to the directions of the two MR actuator units; the torque of the common output member in the antagonistic mode is at most equal to the maximum torque T1, the maximum torque T2, or the maximum torque T3.

[0052] Still further, according to the fifth aspect, for example, the at least two MR actuator units are according to any one of claims 2 to 10.

[0053] In one embodiment, a cooperating device includes two independent and reversible auxiliary power sources (i.e., electric motors); and two selectively engageable magneto-rheological fluid (MRF) clutches connected between the two power sources and a transmission device. The power sources can be operatively connected to the MRF clutches to selectively provide power to the cooperating device via the MRF clutches and, in some configurations, receive energy from the MRF clutches during braking or regenerative braking.

[0054] The collaborative robotic device may further include a controller / drive unit and an energy storage device operatively connected to an auxiliary power source. The auxiliary power source may be directly operatively connected to the human power source and the magnetorheological fluid clutch device. Alternatively, the auxiliary power source is directly connected to the magnetorheological fluid clutch device and operatively connected to the human through engagement with the magnetorheological fluid clutch device.

[0055] The auxiliary power source may be connected to either the input side or the output side of the magnetorheological fluid clutch device.

[0056] These and other objects, features, and advantages of the present invention are provided by a cooperating system comprising: a frame; an additional power source; and an MR fluid actuated device or MR fluid actuator, optionally operatively connected in parallel with a human power input of a power system for applying controllable additional power to the system. In the case of a prosthesis, the MR fluid actuator can also be connected in series with the human power input. The MR fluid actuator preferably comprises: an MR fluid having a controllable apparent viscosity; a housing coupled to the device frame or skeleton and containing the MR fluid; and a rotational shaft extending outwardly from the housing and operatively connected between the MR fluid and the power system.

[0057] A control device, such as a microprocessor operating under program control, can be operatively connected to the MR fluid force modulation device to cause a predetermined magnetic field strength to be applied to the MR fluid based on a selected force modulation program in response to information from the sensor. Accordingly, a desired amount of force or power from an auxiliary power source can be provided to the power system to increase or decrease the power system's output during use of the collaborative robot. The system can further include a sensor that measures human input or power to the system to control the desired output of the auxiliary power source.

[0058] The cooperative system may further include a display operatively connected to the control device. The control device may also include a device for allowing input of program or operating parameters. In addition, one or more sensors may be associated with the MR fluid force modulation device and connected to the control device for generating and displaying on the display the additional force or power provided by the power source.

[0059] MR fluid actuators can be used in all kinds of collaborative systems, such as, but not limited to, robotics and haptic devices. Additionally, power systems can be used in various types of wearable systems, such as exoskeletons, orthoses, body extensions, and human-controlled robots, to name a few.

[0060] In complex collaborative control robots, power systems can be used to move objects by combining human power with an auxiliary power source or multiple power sources. The benefits and principles are the same as for collaborative robotic systems. The goal is still to increase acceleration, improve control of the equipment, or provide greater force or power to the human operating the equipment. An example is a working exoskeleton for supporting tools. Adding a working exoskeleton with MR fluid actuators connected to one or more body components will generate benefits. One or more sensors can be mounted on the component and power can be transmitted to the component in proportion to the effort generated by the user, allowing the user to maintain control of the piece of equipment.

[0061] Among other wearable devices, robotic arms can be mounted directly on the human body. Manual labor is widely used in industrial sectors that process large assemblies, such as aircraft, ships, trains, heavy steel, and construction. Assembly workers' daily tasks often require lifting heavy workpieces and working in non-ergonomic positions, such as lifting arms for extended periods of time. This leads to worker fatigue, increases injury risk, and reduces productivity. A promising approach is to leverage the mobility and dexterity of human workers by augmenting their capabilities with robotics, rather than attempting to completely replace them. Wearable robots address the issue of access to manufacturing sites by leveraging the mobility of human workers. Furthermore, workers can direct the robot's operations in situ without complex programming, resulting in increased versatility compared to traditional robots. Wearable collaborative robotic tools (WCRTs) can be used to assist assembly workers. Due to the high bandwidth of MR fluid actuation, these tools can filter out disturbances caused by humans. Examples include assisting with gravity compensation, applying force on surfaces, or stabilizing the position of an end effector in space. These are just some of the functions that WCRTs can assist with.

[0062] While redundant robotic arms are a promising new type of wearable robot, they present their own challenges. Because the robot is attached to a human, it must be able to complete its tasks despite interference from the human's movements. Consequently, maintaining control output forces—for example, to hold a panel in place—requires actuators capable of very rapid movement. The robot must also be lightweight so as not to hinder the human worker. More specifically, the system's mass must be very close to the human body to avoid exhaustion and counterproductive effects.

[0063] Conventional motor actuation results in a trade-off between speed and torque density. Despite rapid human-based movements, a robot arm using a DC drive motor may have the ability to control its output force, but the robot arm is heavy due to poor force density. On the other hand, a robot using a highly geared motor may be too slow to compensate for human movement. In quasi-static situations, although a geared motor used in conjunction with a force sensor or elastic element can be used to control the output force, it is still a compromise solution with speed limitations and cannot optimally maintain force control when the relative motion is too fast. Magnetorheological fluid actuators can provide good force fidelity for lightweight robots or wearable actuation systems.

[0064] While magnetorheological fluid actuators can provide advantages when used in known configurations, they can provide additional advantages by providing a new modular system comprised of multiple independent MR fluid actuators that can be used in various operating modes. For example, a robotic joint comprised of two (2) MR fluid actuators MRA1 and MRA2 with independent and reversible inputs are both connected to the same output and can be used in multiple modes (e.g., antagonistic and cooperative). In cooperative mode, MRA1 and MRA2 rotate in the same direction (i.e., clockwise), and the maximum torque of MRA1 and MRA2 can be increased to achieve a highly controllable maximum torque in a single direction (i.e., clockwise). In powered mode, MRA1 and MRA2 are in opposite directions (i.e., counterclockwise), and therefore, the maximum torque of MRA1 and MRA2 can be increased to achieve a highly controllable maximum torque in a single second direction (i.e., counterclockwise). In antagonistic mode, MRA1 and MRA2 can rotate in opposite directions (i.e., MRA1 rotates clockwise and MRA2 rotates counterclockwise), each providing highly controllable torque in two opposing directions. It should be understood that in antagonistic mode, the maximum achievable torque of the modular system may be less than that achievable in cooperative mode. However, it should be understood that because the motor of the MR actuator must change direction of rotation to provide torque in two opposing directions at the output, the torque reversal bandwidth in antagonistic mode should be superior to that in cooperative mode. In cooperative mode, one advantage of the modular system is that, compared to conventional actuation systems and known MRF actuators with the same maximum torque output, the sum of the torques of MRA1 and MRA2 can reduce the overall system weight and inertia. This advantage can improve the overall dynamic performance of the device. Furthermore, compared to other robotic systems, the reduced system weight and actuation inertia significantly reduce undesirable impact effects on humans or objects. Another advantage of a modular system comprised of multiple independent MR fluid actuators is that mechanical backlash can be eliminated if MRA1 and MR2 are rotated in opposite directions (e.g., in antagonistic mode). In antagonistic mode, if an impact is detected, the effect can be further reduced by applying force in the opposite direction, without backlash, with high bandwidth, thus reducing the impact energy on the object being impacted. This can be very useful when there is a chance of contact with a potentially injured person.

[0065] In yet another mode, namely, a locked mode, the MR clutches of MRA1 and MRA2 can be independently locked (e.g., by applying a magnetic field). In locked mode, the MR clutch can function as a transfer device with inherent torque-limiting properties, thereby limiting the total output torque of the system to a desired value. In locked mode, the two motors can be independently or jointly controlled to generate a total torque output to the system. For example, the direction (i.e., clockwise) and maximum torque of MRA1 and MRA2 can be increased to achieve maximum torque in a single direction (i.e., clockwise). It should be understood that in locked mode, the total inertia reflected at the output of the system increases due to the increased inertia of the motor and gearbox of each MRA. However, locked mode can have the advantage of eliminating slip between the MR clutch input and output, thereby increasing the durability of the MR device.

[0066] Actuation devices such as robots do not always require high power or high bandwidth. When operations require high torque, cooperative mode may be desirable to accelerate and decelerate the robotic device. Adversarial mode may sometimes be desirable to eliminate backlash and provide high bandwidth. Locking mode may sometimes be desirable to maximize system durability. Thus, a robotic joint composed of multiple MR fluid actuators with independent inputs can benefit from selective control modes.

[0067] Furthermore, a system consisting of more than two MR actuators can allow each actuator to provide torque in a selected direction. This can allow a system having three (3) MR actuators to be prepared to deliver higher torque in a certain direction (i.e., clockwise) where the torque of the two (2) MR actuators is maintained in the same direction (i.e., counterclockwise) while maintaining the opposing mode capability when another MR actuator is rotated (i.e., counterclockwise). In this system having three (3) MR actuators, two MR actuators can be powered by a single motor while the other MR actuator can be powered by a different motor.

[0068] A modular system comprised of multiple independent MR fluid actuators with a single degree of freedom also allows for redundancy, as the device can maintain a portion of its functionality if one component of the MR actuator (e.g., the motor) fails. One or more other MR actuators can still be used to perform their tasks. Thus, modular embodiments with independent MR fluid actuators can provide the ability to mitigate specific failure modes. MR fluid clutch devices are typically designed to transfer torque between an input rotor and an output rotor in response to a given control current supplied to their coils. In the event of a failure in any clutch that generates undesirable torque transfer, the impact on the system can be a loss of control of the output member. For certain applications (e.g., aircraft active engagement or flight surface actuation, automotive steer-by-wire actuation), there may be situations where this type of failure is deemed unacceptable. One possible solution is to limit the input rotor speed to reduce the severity of the failure. This mitigation has the disadvantage of limiting the overall performance of the actuator. Furthermore, because the configuration is inherently redundant, other types of failures, such as motor failure and gearbox failure, to name a few, can be mitigated. The proposed embodiments offer the advantage of independent control of each drive motor (and therefore, each input motor). Thus, the control system can dynamically change the rotational speed of each drive motor to comply with a given safety standard. For example, in a given situation, a loss of control in one direction may be catastrophic, while the severity of the same fault in the opposite direction may be less severe. In this case, the control system can adapt the speed of each input rotor to maintain full performance in the direction where the fault is less severe, while ensuring safety by limiting performance in the direction where the fault could have catastrophic effects.

[0069] In embodiments with multiple MR actuators, the system may be more controllable.

[0070] Thus, in accordance with the present disclosure, a lightweight, low impedance actuation apparatus utilizing a plurality of magnetorheological fluid clutch devices is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 is a schematic diagram of a general magnetorheological (MR) fluid clutch device used in various embodiments of the present disclosure;

[0072] Figure 2 is a perspective view of an assembled MR fluid clutch device of the present disclosure;

[0073] Figure 3 yes Figure 2 A partial cross-sectional view of the MR fluid clutch device;

[0074] Figure 4 yes Figure 2 An exploded view of the MR fluid clutch device;

[0075] Figure 5 yes Figure 2 An enlarged view of the MR fluid clutch device in FIG, showing the magnetic field induced by the coil;

[0076] Figure 6 is a partial cross-sectional view of an MR fluid clutch device with a permanent magnet according to the present disclosure, with the coil in an unpowered state;

[0077] Figure 7 yes Figure 6 A partial cross-sectional view of the MR fluid clutch device with the center coil in a powered state;

[0078] Figure 8 is an embodiment of an MR actuation apparatus using a plurality of MR fluid clutch devices according to the present disclosure;

[0079] Figure 9 yes Figure 8 a fragmentary perspective view of the interior of an actuating device in FIG.

[0080] Figure 10 yes Figure 8 and Figure 9 Simplified representation of the kinematic chain of the MR actuation device in;

[0081] Figure 11 yes Figure 8 An exploded view of the MR actuation device in FIG.

[0082] Figure 12 yes Figure 8 A perspective cross-sectional view of an MR actuation device in FIG.

[0083] Figure 13 yes Figure 8 A cross-sectional view of the MR actuation device in FIG.

[0084] Figure 14 yes Figure 8 Schematic representation of the MR actuation device used in the robotic arm;

[0085] Figure 15 yes Figure 8 Schematic representation of the MR actuation device used in the wearable robotic arm;

[0086] Figure 16 yes Figure 8 Schematic representation of the MR actuation device in high force / low bandwidth mode;

[0087] Figure 16 'yes Figure 8 Schematic representation of the MR actuation device in low-force / high-bandwidth mode;

[0088] Figure 17 yes Figure 8 A schematic representation of an MR actuation device consisting of two or more MR fluid clutch devices;

[0089] Figure 18 is a schematic representation of a controller for controlling two MR fluid clutch devices of an MR actuation apparatus when the two MR fluid clutch devices remain slipping;

[0090] Figure 19 is a schematic representation of a controller for controlling two MR fluid clutch devices of an MR actuation apparatus when the two MR clutch devices are maintained in a locked mode;

[0091] Figure 20 is a schematic representation of an event selector-based method for determining a desired mode for an MR actuation device;

[0092] Figure 21 yes Figure 18 Schematic representation of the sliding velocity and MR torque reference of the MR actuation device in FIG;

[0093] Figure 22 is used Figures 1 to 7 a schematic representation of a multi-DOF actuation apparatus for any MR fluid clutch device in; and

[0094] Figure 23 yes Figure 8 Schematic representation of multiple MR actuation devices used in a robotic arm;

[0095] Figure 24 yes Figure 8 Schematic representation of the MR actuation device used to control the ball screw;

[0096] Figure 25 yes Figure 24 Schematic representation of an MR actuation device for actuating a ball screw;

[0097] Figure 26 is a schematic representation of an enhanced reliability controller for controlling an MR actuation device when the MR actuation device is used; and

[0098] Figure 27 is a schematic perspective view of a variation of an MR actuation device using spiral bevel gears according to the present disclosure. DETAILED DESCRIPTION

[0099] refer to Figure 1, illustrates a general magnetorheological (MR) fluid clutch device 10 configured to provide a mechanical output force based on a received input current provided by a processor unit 1 that controls the MR fluid clutch device 10. The processor unit 1 is any type of electronic or electrical device with control capabilities to control the input current sent to the MR fluid clutch device 10. As explained below, in embodiments, the processor unit 1 can receive signals from sensors and, through firmware, calculate data to control the operation of the MR fluid clutch device 10 based on settings, requested assistance, and the like. The MR fluid clutch device 10 includes a drive member 20 having a disk 22 with drums 21 protruding axially therefrom. This assembly is also referred to as the input rotor 20. The MR fluid clutch device 10 also includes a driven member 40 having a disk 42 protruding therefrom, interwoven with the drums 21 to define an annular chamber filled with MR fluid F. The assembly of the driven member 40 and drums 41 is also referred to as the output rotor 40. As described below, the annular chamber is defined by a casing 40' integral with the driven member 40. Therefore, because it cooperates with the roller 21 during torque transmission, the surfaces of the casing 40 facing the roller 21 are referred to as shear surfaces. The driving member 20 may be an input shaft in mechanical communication with a power input, and the driven member 40 may be in mechanical communication with a power output (i.e., force output, torque output). The MR fluid F is a smart fluid composed of magnetic particles disposed in a carrier fluid, typically an oil. When subjected to a magnetic field, the fluid can increase its apparent viscosity, potentially to the point of becoming a viscoplastic solid. The apparent viscosity is defined by the ratio of the operating shear stress of the MR fluid F contained within the opposing shear surfaces—i.e., the opposing shear surfaces of the rollers 21 and 41 on the drive side and the shear surface of the casing 40' in the annular chamber—to the operating shear rate. The magnetic field strength primarily affects the yield shear stress of the MR fluid. When in its activated ("powered-on") state, the yield shear stress of the fluid, i.e., the input current, can be controlled using a controller such as the processor unit 1 by varying the strength of the magnetic field generated by the electromagnet 35 integrated into the housing 40 ′. Accordingly, the electromagnet 35 can be utilized to control the ability of the MR fluid to transmit force, thereby acting as a clutch between the components 20 and 40. The electromagnet 35 is configured to vary the strength of the magnetic field so that the friction between the components 20 and 40 can be low enough to allow the driving component 20 and the driven component 40 to rotate freely, and vice versa, i.e., to engage in controlled sliding.

[0100] Like a rotary gear motor, the drive member 20 is driven at a desired speed by a power source, and the output rotor is connected to a controllable mechanical device. The torque transmitted by the MR fluid clutch device 10 is related to the strength of the magnetic field passing through the MR fluid. The magnetic field strength is modulated by the coils of the electromagnet 35, as controlled by the processor unit 1.

[0101] refer to Figure 2 、 Figure 3 ,as well as Figure 4 The MR fluid clutch device is generally shown as a whole at 10. The MR fluid clutch device 10 has Figure 1 The MR fluid clutch device 10 has similar components to those of the general exemplary MR fluid clutch device 10 in FIG. 1 , and thus, like reference numerals refer to like components. The MR fluid clutch device 10 has an input rotor 20 (also referred to as a driving member), a stator 30 (including coils), and an output rotor 40 (also referred to as a driven member), and MR fluid is located in an MR fluid chamber defined in a free space including the space between the rollers of the rotors 20 and 40.

[0102] Like a rotary internal combustion engine or electric motor, the input rotor 20 can be driven at a constant or variable speed dictated by a rotary power source (not shown). The output rotor 40 is connected to a controllable mechanical output (not shown). When current circulates in the coils 35 of the stator 30, a magnetic field is induced in the stator 30 and passes through the rollers and the MR fluid F. Depending on the strength of the magnetic field, torque is then transmitted from the input rotor 20 to the output rotor 40 by shearing the MR fluid F between the rollers. Although the following description indicates that the rotor 20 is the input rotor and the rotor 40 is the output rotor, it is noted that the rotor 20 can be the output rotor and the rotor 40 can be the input rotor. However, for the sake of clarity and simplicity, and to avoid unnecessary redundancy, the description will refer to the "input rotor 20" and "output rotor 40."

[0103] from Figure 3 and Figure 4 As can be seen clearly in FIG, the input rotor 20 has an inner magnetic core 20A and an outer magnetic core 20B that are spaced apart from each other. The inner magnetic core 20A and the outer magnetic core 20B are made of a ferromagnetic material (such as silicon iron) having high magnetic permeability, high magnetic saturation, high resistivity, and low hysteresis. The material with high resistivity allows for faster magnetic field buildup by minimizing eddy currents, thereby achieving enhanced dynamic performance.

[0104] The cylindrical input roller 21 is fixed to the roller holder 22 (also called a disk, plate, ring, etc.), and the roller holder 22 spans the radial space between the inner magnetic core 20A and the outer magnetic core 20B. In an embodiment, the rollers 21 are assembled tightly in the channels of the roller holder 22 and the dowel pins 23 pass through all the rollers 21. Figure 3 and Figure 4 As shown in FIG, the dowel pin 23 may also penetrate the inner core 20A. The roller retainer 22 may be made of a non-ferromagnetic material to minimize the magnetic field passing through the roller retainer 22, and the roller retainer 22 may also have a high resistivity to minimize resistive losses during transient operation of the MR clutch device 10.

[0105] In many other embodiments, the input rotor 20 can be driven by a power source through a drive gear, or any other drive member (e.g., a sprocket, a belt, a friction device). For illustrative purposes, a gear portion 24 is provided for interconnection with a gear (not shown), and the gear portion 24 is a toothed gear that cooperates with the drive gear. The gear portion 24 can be tightly fitted, glued, or completely locked to the outer core 20B using mechanical fasteners or the like.

[0106] A cover 25 is secured to the outer magnetic core 20B and, in one embodiment, is made of aluminum for cooling purposes. Heat sinks 25A may be present on the cover 25 to cool the MR fluid clutch device 10 through forced convection as the input rotor 20 rotates. Heat sinks 25A help reduce the operating temperature of the MR fluid and thereby improve the life of the MR fluid clutch device 10. The cover 25 may press an end-face static seal 25B against the outer magnetic core 20B to prevent MR fluid leakage. A fill port 25C may be defined by the cover 25 to allow the MR fluid clutch device 10 to be filled with MR fluid. As shown, the fill port 25C may be tapped and plugged using a sealed set screw 25D, among other solutions.

[0107] Central hole 25E in cover 25 is sealed by an expansion chamber cap 26A equipped with a flexible membrane 26B to allow the MR fluid to expand during temperature increases or undergo phase changes as it ages. To prevent membrane 26B from bulging due to the MR fluid, a compliant material, such as polyurethane foam, may be placed in the empty expansion volume between expansion chamber cap 26A and flexible membrane 26B. The compliant material thus applies a biasing pressure to membrane 26B. Furthermore, vents may be present in expansion chamber cap 26A to prevent excessive pressure from accumulating in the empty expansion volume. Expansion chamber 26 may also be formed from a compressible material (e.g., closed-cell neoprene), which occupies less volume as pressure in the MR fluid F increases. If a compressible material is present, the expansion chamber may not require vents and membrane 26B.

[0108] Still refer to Figure 3 and Figure 4 The stator 30 is made of ferromagnetic material to guide the magnetic field. The stator 30 may have an annular body with a U-shaped cross section formed by an annular cavity 30A. The inner magnetic core 20A is received in the annular cavity 30A. The annular cavity 30A may be defined by an inner annular wall 31A, an outer annular wall 31B, and a radial wall 31C. The inner annular wall 31A, the outer annular wall 31B, and the radial wall 31C may be a single piece. The inner magnetic core 20A is made to rotate by one or more bearings 32. Figure 3 and Figure 4 A pair of bearings 32 are shown. Although bearings 32 are shown positioned between inner magnetic core 20A and stator 30, bearings 32 are considered to be positioned anywhere within inner magnetic core 20A, such as within the radial fluid gap described below. For example, stator 30 is connected to a structure via holes located on its outer surface 33 (i.e., a portion of radial wall 31C) and, thus, is a non-movable component of MR fluid clutch device 10 relative to the structure.

[0109] from Figure 5 As best seen in FIG, the dimensions of stator 30 define radial fluid gaps 34A and 34B between stator 30 and inner and outer magnetic cores 20A and 20B, respectively. During use, radial fluid gaps 34A and 34B are filled with a fluid, such as air or other gases, or a lubricating and / or cooling liquid, such as oil or grease. Thus, radial fluid gaps 34A and 34B are free of solid matter during use. For example, an adhesive is used to secure coil 35 to the annular body of stator 30. It is contemplated that slots may be provided through stator 30 to allow wires connected to coil 35 to pass through, thereby powering MR fluid clutch device 10. As described below, stator 30 further includes one or more bearings 36 for rotatably supporting outer rotor 40.

[0110] Coil 35 can be wound using a high-copper ratio winding method. A higher copper ratio can lead to improved efficiency. Furthermore, winding methods that allow for flat wire winding, horizontal stacking, and cylindrical stacking are also contemplated. Multi-layer PCBA windings (heavy copper PCBAs) are also contemplated, not just copper.

[0111] Bearings 32 / 36 are lubricated and non-contact seals can be used to limit friction losses. The bearing arrangement, characterized by a bearing between the input rotor 20 and the stator 30, and a separate bearing between the stator 30 and the output rotor 40, enhances the safety of the MR fluid clutch device 10. For example, if the input rotor 20 becomes stuck by the stator 30, the output rotor 40 can still rotate freely. Conversely, if the output rotor 40 becomes stuck by the stator 30, the power source driving the input rotor 20 can still rotate.

[0112] The output rotor 40 comprises a cylindrical output roller 41 secured to a roller retainer 42 (e.g., a plate, disk, etc.) via a close-fitting assembly located on the inner diameter of the roller 41. A dowel pin 43 may extend through the roller 41, in addition to other means of connecting the output roller 41 to the roller retainer 42. The output roller 41 is ferromagnetic, allowing the magnetic field to easily pass through it (e.g., with equal magnetic flux in each roller). The roller retainer 42 is made of a non-ferromagnetic material (e.g., an aluminum alloy) to minimize the magnetic field passing through the roller retainer 42, thereby reducing the inertia of the output rotor 40.

[0113] The roller retainer 42 has a shaft interface 44 through which the roller retainer 42 is connected to the shaft 45. In an embodiment, the shaft interface 44 is a sleeve-like component that is rotationally coupled to the shaft 45 and may have wear-resistant sleeves 44A and 44B. The output rotor 40 is rotationally locked to the output shaft 45 by a key or any other locking device (spline, tight fit, etc.). The sealing shaft cap 46 is used to axially retain the output rotor 40 relative to the output shaft 45 and to prevent leakage of the MR fluid. A flat portion for the key may be defined on the output shaft 45 to facilitate tightening the shaft cap 46. This arrangement is one arrangement, among other arrangements, for connecting the roller retainer 42 to the shaft 45 so that the shaft 45 can receive drive actuation from the input rotor 20 via the roller retainer 42. The roller retainer 22 further includes through holes 47 circumferentially distributed therein to allow circulation of the MR fluid. As Figure 3 and Figure 4 As shown in FIG, the through hole 47 is located between the roller 41 and the shaft interface 44.

[0114] The MR fluid clutch device 10 can utilize an odd number of rollers 21 and 42, for example, an average of approximately seven. A greater or fewer number of rollers can be utilized depending on the application. Because the use of multiple rollers helps reduce the roller length and cross-section of the inner and outer magnetic cores 20A, 20B, for a given required torque and a given diameter, utilizing more than one roller helps reduce the overall volume and weight of the MR fluid clutch device 10. Furthermore, when the cross-section of the magnetic core is smaller, the temporal response of the magnetic circuit can be improved because internal eddy currents are minimized.

[0115] refer to Figure 5The magnetic field F induced by coil 35 follows a closed path through annular wall 31B of stator 30, radial fluid gap 34B, outer magnetic core 20B, MR fluid, rollers 21 and 41, inner magnetic core 20A, and radial fluid gap 34A. Radial fluid gaps 34A and 34B allow coil 35 to be energized without the use of slip rings. In effect, typical friction slip rings are replaced by magnetic slip rings implemented by two radial fluid gaps 34A and 34B. The radial fluid gaps 34A and 34B are radial rather than axial for two reasons. First, radial tolerances are easily met, allowing the fluid gaps to be quite small (<0.2 mm). This minimizes the number of additional coil turns required to magnetize the fluid gaps 34A and 34B. Second, due to the rotational symmetry of the fluid gaps 34A and 34B, the magnetic attraction forces in the fluid gaps 34A and 34B between stator 30 and magnetic cores 20A and 20B are nearly canceled. If the fluid gap is axial, there will be a greater magnetic attraction force and will load the bearing axially.

[0116] refer to Figure 6 and Figure 7 In yet another embodiment, an MR fluid clutch device 10 is shown. Figure 6 and Figure 7 The MR fluid clutch device 10 and Figures 3 to 6 The MR fluid clutch device 10 in FIG. 1 has many similar components, and therefore, similar elements will be referenced with similar numbers, and their descriptions need not be repeated here. The difference is that, in addition to the coil 35, a permanent magnet 100 is present in the outer annular wall 31B.

[0117] like Figure 6 As shown in FIG, permanent magnet 100 is used to generate magnetic field F1 in MR fluid clutch device 10, enabling device 10 to deliver a constant output torque without applying current through coil 35. Permanent magnet 100 is radially magnetized and can be a complete solid annular part or an assembly of individual magnets (such as a cylindrical magnet). Other radial fluid gaps 101A and 101B, "redirection gaps," separate portions of annular wall 31B located on opposite sides of permanent magnet 100, excluding coil 35, from inner and outer cores 20A, 20B.

[0118] When no current is applied to the coil 35, as shown in FIG. Figure 6According to the magnetic flux paths described and shown, a magnetic field F1 exists in the MR fluid. Some of the magnetic flux circulates through other radial fluid gaps 101A and 101B, separating the stator 30 from the inner and outer magnetic cores 20A and 20B. These gaps 101A and 101B are somewhat wider than gaps 34A and 34B, with width being in the radial direction. The width of the redirection gaps 101A and 101B controls the amount of magnetic flux required in the MR fluid, i.e., the desired constant torque when no current is applied to coil 35. If the redirection gaps 101A and 101B are sufficiently wide, the magnetic flux induced by permanent magnet 100 passes almost entirely through the MR fluid, resulting in higher DC torque. If the redirection gaps 101A and 101B are radially narrower, the magnetic flux is shared between the MR fluid and the redirection gaps 101A and 101B, resulting in lower DC torque.

[0119] When based on Figure 7 When current is applied to coil 35, the magnetic flux induced by permanent magnet 100 is redirected within redirection gaps 101A and 101B, indicated by F2, resulting in a reduction in torque within MR fluid clutch device 10. At a certain coil current intensity, magnetic flux F1 in the MR fluid is nearly canceled and, after exceeding this intensity, increases again. The width of the redirected radial fluid gap also controls the winding size of coil 35. A higher width requires a larger winding to redirect the magnetic flux.

[0120] If current is applied in the opposite direction, the coil 35 assists the permanent magnet 100 in generating magnetic flux in the MR fluid, resulting in an increase in the torque of the MR clutch device 10 .

[0121] Accordingly, due to the magnetic field induced by the permanent magnet 100, the MR fluid clutch device 10 normally maintains an "energized state" with respect to the MR fluid. Therefore, power can be supplied to the coil 35, causing the MR fluid clutch device 10 to reduce torque transmission and ultimately enter a de-energized state. This arrangement is useful, for example, when the MR fluid clutch device 10 must maintain torque transmission despite being de-energized. The magnetic field of the permanent magnet 100 is of sufficient magnitude to enable the MR fluid clutch device 10 to support a load even when not powered.

[0122] refer to Figure 8 , indicating the use of Figures 1 to 7 An embodiment of the MR actuation apparatus 80 of a plurality of MR fluid clutch devices of any of the Figures, and Figures 1 to 7Any one or any combination of fluid clutch devices shown in any of the figures in the drawings can be used with the MR actuation device 80 and other devices described herein. For simplicity, the embodiment shows a rotatable robotic joint, but the same principles can be applied to other types of rotatable or translatable devices. The described embodiment has two MR fluid clutch devices 10A and 10B powered by two independent motors MA and MB, but other embodiments may have additional MR fluid clutch devices powered by additional motors. Motors MA and MA, as well as other motors used, are of the bidirectional type. The MR actuation device 80 has an outer housing 81 that attaches to a structure or robotic component using mounting holes 82. This is one way to secure the MR actuation device 80 to a structure, linkage, or the like; other methods include integral connections, straps, and the like. The MR actuation device 80 has a rotary joint output member 83 that attaches to a second component using mounting holes 84. Mounting holes 84 can be threaded, keyed, or the like. Other possibilities for output member 83 include spline couplings, flanges, and the like. In some embodiments, motor MA or motor MB can be of an electrical type with bidirectional capability (e.g., the motor can selectively rotate in both directions), although the motor can also be unidirectional. It should be noted that motor MA and motor MB can be equipped with internal braking devices to brake their outputs. The braking devices in motors MA and MB can be of the energized or de-energized type. Alternatively, the MR actuator device 80 can be equipped with an independent braking device of the energized or de-energized type, or can rely on the motor resistance for braking.

[0123] refer to Figure 9 , shows the interior of the MR actuation device 80 with a portion of the housing 81 removed. The motor MA is connected to the cover 25 of the MR fluid clutch device 10A and the motor MB is connected to the cover 25 of the MR fluid clutch device 10B using a gear type connection, the cover 25 being the input portion of the MR fluid clutch devices 10A and 10B. As an option, the gear type connection is achieved by parallel spur gears, but other transmission arrangements are also possible, including pulleys and belts, sprockets and chains, etc. As a possibility, the housings of the motors MA and MB can be attached to the actuation device cover 95. The gear output 90A (not shown) of the motor MA can be connected to the gear portion 24A of the MR fluid clutch device 10A, while the gear output 90B of the motor MB can be connected to the gear portion 24B of the MR fluid clutch device 10B. In this embodiment, the motors MA and MB are directly connected to the MR fluid clutch devices 10A and 10B, respectively, thereby providing Figure 10The first reduction ratio R1B is better than 1. In other embodiments, although optional, an additional reduction mechanism (i.e., a planetary gearbox, a belt reduction mechanism, an infinite screw) may be provided between the motors MA and MB and the MR fluid clutch devices 10A and 10B. In an embodiment, the output shaft (not shown) of the MR fluid clutch device 10A is connected to an output gear (not shown), while the output shaft 45B of the MR fluid clutch device 10B is connected to an output gear 91B (for the MR fluid clutch device 10A, 45B and 91B are visually equivalent). The output gear of the MR fluid clutch device 10A can be connected to another gear 92A, while the output gear 91B can be connected to another gear 92B, thereby providing a certain level of reduction ratio downstream of the MR fluid clutch devices 10A and 10B, which is identified as Figure 10 The second deceleration level R2B in Figure 10 As shown in , a third reduction level R3B can be added consisting of gears 93A and 93B connected to an output gear 94. Gear systems or other types of reduction arrangements may have fewer or more reduction levels. Thus, the MR actuator device 80 used as a robotic joint is composed of two independent MR actuator units, each characterized by its dedicated motor MA, MB, MR fluid clutch device 10A, 10B, and a transmission device, such as in the form of a reduction mechanism. The MR actuators are connected to the same robotic joint output member 83. Each of the two MR actuator units has an MR fluid clutch device with lower inertia, so that if the MR fluid clutch device is not used, the inertia reflected by the transmission to the mechanical system via the output member 83 may be lower. Moreover, compared to a system consisting of a single motor with double capacity combined with two opposing MR fluid clutch devices, where the capacity of each MR fluid clutch device is increased (e.g., doubled) and therefore the inertia and weight are increased, having MR actuator units MRAA and MRAB with independent (each actuator unit has its own motor) control (such as Figure 16 The advantages of a system with a lower inertia MR fluid clutch device (shown in FIG) will help keep the weight and inertia at the output lower. The weight reduction of the configuration in which two small MR fluid clutch devices are used can also lead to a reduction in the size and weight of the MR actuator device, thereby leading to a reduction in the weight of the mechanical assembly and / or a reduction in the inertia of the mechanical assembly itself. For a given torque, in order to reduce weight, the system can have two MR fluid clutch devices per DOF, as shown in FIG. Figures 9 to 12In the embodiment of the present invention, the MR actuator devices 80 have the following situations: 10A and 10B, each MR actuator device 80 is driven by an independent motor (e.g., MA, MB) and coupled to a rigid link capable of transmitting bidirectional force. Each independent MR actuator unit, e.g., MRAA and MRAB, can also allow different operating modes than non-independent control. An electronic controller (such as 1 in the aforementioned figure) can be used to Figures 9 to 12 The MR actuator device 80) may be embedded in the MR actuator device 80 and the line path 96 ( Figure 9 ) can be used to route wires to the motors MA and MB, the coils 25 of the MR fluid clutch devices 10A and 10B, and other integrated sensors such as Hall effect, torque sensors, position sensors, inertial sensors, temperature sensors, to name a few.

[0124] Figure 10 yes Figure 9 A simplified representation of the MR actuator device 80 is shown in FIG. Figure 11 is an exploded view of the actuation device 80, and Figure 12 is a perspective sectional view of the actuating device 80. In it, the kinematic chain of the MR actuator unit MRAB with the associated components can be seen in more detail, i.e., the structural components are removed. When engaged, the MR fluid clutch device 10B can transmit the torque generated by the motor MB to the output gear 94, which is an internal gear type. Therefore, the kinematic chain can be composed of the motor MB, the gear output 90B, the gear part 24B of the MR fluid clutch device 10B, the output gear 91B connected to the gear 92B (forming the second reduction R2B). The gear 92B can then be connected to the output gear 93B via the shaft 102B and can then be connected to the output gear 94, and the output gear 93B serves as the pinion of the internal gear 94, although this is only an option among others. Similarly, but not fully shown, the kinematic chain of the actuator unit MRAA can be composed of the motor MA, the gear output 90A ( Figure 11 ), the gear portion 24A of the MR fluid clutch device 10A, and the output gear 91A connected to the gear 92A (forming the second reduction gear R2A). The gear 92A can then be connected to the output gear 93A via the shaft 102A and can then be connected to the output gear 94. Thus, the MR actuator units MRAA and MRAB have the output gear 94 as a common output (i.e., a common output, a single output for all MR actuator units). It should be noted that many of these components can be combined into a single component. As an example, among others, the gear 92B, the shaft 102B, and the output gear 93B can constitute a single part. In Figures 9 to 13In the embodiment shown, a spur gear reduction system is shown, however, other types of reduction mechanisms may be used, such as helical, worm, friction, magnetic, belt, chain, to name a few. Figures 8 to 13 , MR actuator units MRAA and MRAB are shown with components having the same dimensions (e.g., MR fluid clutch device 10A is shown having the same dimensions as MR fluid clutch device 10B). However, the MR actuator units MRAA and MRAB, or any one or more components comprising the MR actuator units MRAA and MRAB, may have different dimensions when compared to the MR actuator units MRAA and MRAB. For example, the dimensions of the MR actuator unit MRAA may be used for higher torque or speed than the MR actuator unit MRAB. The MR fluid clutch device 10A may have different dimensions than the MR fluid clutch device 10B. For example, this arrangement may be desirable when the MR actuator unit MRAA is used to compensate for gravity on a robotic arm, while the MR actuator unit MRAB is used only to apply force to a surface. It should be understood that the gears of the MR actuator units MRAA and MRAB may not have the same reduction ratio or the same number of reduction steps. For example, the MR actuator unit MRAA may have a first reduction gear R1A, a second reduction gear R2A, and a third reduction gear R3A, while the MR actuator unit MRAB may have only a first reduction gear R1B and a third reduction gear R3B, with the output gear 91B directly connected to the shaft 102B. There are other embodiments in which the MR actuator units MRAA and MRAB may differ from each other in terms of torque output, speed, reduction ratio, etc.

[0125] exist Figures 9 to 13 In the embodiment, as an option, use the usual Figures 3 to 5 The MR actuating device 80 is similar to an open type MR fluid clutch device. Therefore, in the power-off mode (no power is supplied to the MR clutch device coil), the MR actuating device 80 can rotate freely. It should be noted that the reduction mechanism is supported by bearings, but for the sake of simplicity, it is not described in detail. For example, Figure 9 and Figure 13 As seen in FIG, the housing 81 may integrate bearing supports and bearings, including rotationally supporting the rotating components of the MR actuator units MRAA and MRAB by using the housing cover 81A.

[0126] Figure 14 is a schematic representation of a plurality of actuation devices 80 (shown as 80A, 80A', 80B, 80B') used in a haptic robotic arm system 140. MR actuation devices 80A and 80A' actuate a first haptic arm 141 and MR actuation devices 80B and 80B' actuate a second haptic arm 142, with the MR actuation devices 80 being the actuation joints between the links.

[0127] Figure 15 is a schematic representation of multiple MR actuation devices 80 used in the wearable robotic arm 150. In the configuration, the MR actuation devices 80 and 80' each provide a certain degree of freedom to achieve a wearable arm with multiple degrees of freedom, and the MR actuation devices 80, 80' are the actuation joints between the links.

[0128] Figure 16 and Figure 16 ' is a schematic representation of an MR actuation device 80 showing control modes. The MR actuation device 80 has two MR fluid actuator units MRAA and MRAB connected to the same joint output member 83 that can be used in multiple modes. Figure 16 , the MR actuation device 80 is shown as operating in collaborative mode. In collaborative mode, the motor MA of MRAA and the MB of MRAB operate to provide torque to a common output 83 in the same direction, and the torque generated on the robot joint output member 83 will be the sum of the torques generated by the MR actuator unit MRAA and the MR actuator unit MRAB controlled by the MR fluid clutch devices 10A and 10B respectively. For the motors MA and MB, the system can be arranged to rotate in opposite directions, but still have their transmission arrangements arranged to cooperate with the output member 83 so that the torque on the output member 83 is the sum of the torque generated by the MRAA controlled by the MR fluid clutch device 10A and the torque generated by the MRAB controlled by the MR fluid clutch device 10B. In the embodiment in which the motors MA and MB rotate in the clockwise (CW) direction Figure 16In this embodiment, the torque generated at the output member 83 (e.g., serving as a robot joint) can also be CW. Optionally, although more or fewer reduction mechanisms may be present, the first reduction mechanism R1A is positioned between the motor MA and the clutch 10A, and the second reduction mechanism R2A is positioned between the clutch 10A and the robot joint output member 83. Furthermore, although more or fewer reduction mechanisms may be present, the first reduction mechanism R1B is positioned between the motor MB and the clutch 10B, and the second reduction mechanism R2B is positioned between the clutch 10B and the robot joint output member 83. In some other embodiments, any or all of the reduction mechanisms R1A, R2A, R1B, and R2B may be eliminated. Additional reduction mechanisms may be added to any reduction mechanism to increase the reduction ratio. Additional reduction mechanisms may also be added after the robot joint output member 83 (i.e., between the robot joint output member 83 and the robot member link). All reduction mechanisms may be of any type that allows the input to rotate at a different speed (slower or faster) than the output. The reduction mechanisms may be of any type or any combination of types. In a higher force / lower bandwidth mode, where the MR actuator units MRAA and MRAB rotate in the same direction (i.e., clockwise), the torques of MRA1 and MRA2 can be increased to achieve a highly cooperative higher torque in a single direction (i.e., clockwise). Figure 16' represents an antagonistic mode in which the MR actuator units MRAA and MRAB rotate in opposite directions (i.e., the MR actuator unit MRAA rotates clockwise and the MR actuator unit MRAB rotates counterclockwise). In this mode, the MR actuator units MRAA and MRAB can each provide highly controllable torque in two opposite directions. In the lower force / higher bandwidth mode, the maximum torque available in the system is less than the torque available in the higher force / lower bandwidth mode (i.e., the collaborative mode). However, because the motors MA and MB of the MR actuator units MRAA and MRAB do not need to change rotational direction, the torque reversal bandwidth in the antagonistic mode is more reversible than in the collaborative mode to provide torque at the robot joint output member 83 in two opposite directions. In other words, in the collaborative mode, if one motor changes direction to switch to the antagonistic mode, the bandwidth will be reduced, i.e., the torque reversal may not be as fast. In each mode, the maximum torque limit and maximum speed limit of each MR actuator unit MRAA and MRAB can be adjusted independently. This provides the ability to independently adjust the performance of the MR actuator device 80 in each direction, relative to conditions or larger control algorithms or sensors, thus becoming state-dependent. In summary, a cooperative mode involves forces from two or more sources acting in a common direction or vector at the output, while an antagonistic mode involves forces from two or more sources acting in an antagonistic manner at the output (i.e., sequentially in different directions), with the MR fluid clutch device 10 dedicated to torque transmission and the controller 1 operating the system to control mode selection. The system is described herein with respect to an exemplary use with a robotic joint, but the MR actuator device 80 can be coupled to any type of mechanical output. It can be coupled to a rotation-to-rotation converter (e.g., a gear, pulley, sprocket, linkage, or other type of rotary mechanical device), a rotation-to-linear converter (e.g., a screw, ball screw, rack and pinion, or other type of linear mechanical device), or a combination of the two (e.g., a pulley acting on a cable or belt pulled on a sliding mechanism, a ball screw acting on a rotary joint, or other type of combined mechanical device).

[0129] Figure 17The MR actuator device 80 is composed of n MR actuator units. In this configuration, multiple MR actuator units MRA are connected to the same joint output member 83. The torque generated by the actuator device output member 83 on the robot member (not shown) is the sum of the torques (positive or negative) generated by all MR actuator units. As an option, two motors are bidirectional, and if the motors are used only in antagonistic mode, the motors of the other MR actuator units can be unidirectional. Depending on the conditions, the multiple MR actuator units can cooperate to apply force in a desired direction. The multiple MR actuator units can be reorganized (the motors can change direction) to enable the system to generate or prepare to generate external force. The number of MR actuator units that cooperate to generate force in a desired direction can be changed in real time, allowing the MR actuator device 80 (for example, at the robot joint in an embodiment) to quickly change its impedance characteristics. Different arrangements can be implemented: two MR actuator units MRA cooperate in cooperative mode and a third MR actuator unit is in antagonistic mode, eg all MR actuator units sum their torques in cooperative mode.

[0130] Figure 18 is a schematic representation of a controller for controlling two MR actuator units of an MR actuation apparatus (e.g., 80) when the two MR clutch devices are kept slipping. The controller can be used as controller 1 in the figure. In this situation, the input roller 21 rotates faster than the output roller 41 to keep the clutch 10 slipping or continuously slipping. In this situation, the torque transmitted by the system is controlled by the current transmitted to the coil 35 of the MR fluid clutch device. Using this controller, many sub-modes are possible. For example Figure 16 As shown in ', when the two MR actuator units rotate in opposite directions, the first possible mode is the antagonistic mode (or applying antagonistic forces at the output), and in which the backlash of the system is reduced due to the antagonistic nature of the forces generated on the mechanical system. The second operating mode is the cooperative mode, in which, as shown in Figure 16As shown in FIG, two MR actuators rotate in the same direction (or apply force in a common direction or at an orientation at the output). In this mode, higher torque is possible, and since both motors apply force in the same direction, the system may experience backlash. A third mode is possible, in which one MR actuator remains sliding and the other actuator remains in another mode (i.e., power-off mode, locking mode, or braking mode). Because the system is fully controllable, it is possible to switch very quickly from one mode or sub-mode to another through operation of the controller 1. In embodiments, the system can be operated in cooperative mode to perform operations in one direction, and if a direction change is required, switch to antagonistic mode to perform the direction change to instantly eliminate the backlash effects of the direction change, and then return to cooperative mode to accelerate the robotic member. Furthermore, a controller for two MR actuators is shown, but controllers with one or more additional MR actuators are also possible. When multiple MR actuators cooperate with each other, the result can be that the system still operates in the various modes and sub-modes illustrated, and the mechanical system benefits from increased flexibility with respect to the forces generated in one direction or the other. Depending on the number of MR actuators providing force in one direction versus another, a system can have asymmetric actuation capabilities. Indeed, with a three-MR actuator system of equivalent capabilities (torque, speed, etc.), if two MR actuators are configured to provide force in one direction (i.e., CW) and one MR actuator is configured to provide force in the opposing direction (CCW), the torque capability in the CW direction can be twice that in the CCW direction. Furthermore, if a multi-MR actuator system is comprised of MR actuators with varying capabilities (torque, speed, power, etc.), it can select one or more actuator adjustments to benefit from additional sub-modes not described here. The system operates as needed. Systems with more than two or more MR actuators can benefit from a level of redundancy.

[0131] Figure 19Figure 1 is a schematic representation of two MR actuator controllers controlling the actuation devices when two MR clutch devices are held in locked mode. In this mode, the current in coil 35 is adjusted so that the torque transmitted by the MR fluid clutch device 10 is below the maximum transmittable torque of the MR fluid clutch device. Consequently, the input roller 21 and the output roller 41 have the same speed, keeping the clutch 10 in locked mode (no slip). In this locked mode, the current generated by the motor controls the torque transmitted by the actuation devices. Again, a controller with two MR actuators is shown here, but additional MR actuators can be added. In this locked mode, only one MR actuator can be used to control the torque transmitted to the mechanical system. It is also possible to use two or more MR actuators in coordination to generate force on the mechanical system. A locked mode, in which one or more MR actuators generate torque on the system, can limit slip in the MR clutch device 10 and reduce the energy dissipated in the MR fluid F. This locked mode can be used to increase the durability of the fluid F in each MR fluid device 10.

[0132] Figure 20 FIG1 is a schematic representation of an event-based selector for determining the desired mode of the system. The event-based selector can be a module in the form of non-transitory computer-readable instructions executed by the processor of controller 1. Depending on the conditions of use and the desired behavior of the mechanical system, individual MR fluid actuators can be switched very quickly from one mode (antagonistic, cooperative, or locked mode) to various sub-modes (antagonistic, cooperative, and state-dependent). This allows the system to be very versatile in terms of controllability. Controller 1 can operate the event-based selector using signals from a variety of sensors applied to various components of the system.

[0133] Figure 21 is a simplified representation of one possible (among other) solution for producing event selectors. Figure 21 When the required torque T MR Than the single MR actuator MRmax High, Figure 18 The sliding speed commands Slip1_ref, Slip2_ref and the MR torque reference of the controller in are used to switch between the antagonistic mode and the cooperative mode.

[0134] Figure 22is a schematic representation of a multiple DOF actuation system with MR actuator units (eight are shown) working in collaboration, and the spherical shape is a common output (e.g., as part of a ball joint or swivel). In this configuration, specific DOF (i.e., translation in x, y, and z) can be locked. In this configuration, at least nDOF+1 MR actuator units can collaborate to generate a force (x, y, or z) or torque (Mx, My, or Mz) in a desired direction. Moreover, each MR actuator unit can be composed of multiple MR actuators themselves. In this configuration, the force or torque provided in one direction can be the sum of the torques of multiple MR actuator units that collaborate to apply force in the desired direction. Due to the low impedance characteristics of the MR actuator units provided by the use of an MR fluid clutch device, the MR actuator units can be controlled in force only, and therefore, force collaboration is allowed. Systems with high impedance and therefore low bandwidth result in force conflicts between the actuators, and therefore, it can be difficult to accurately control or adjust the generated force. In this Figure 22 In a MR actuator device, eight MR actuator units cooperate to actuate an actuation output, such as a platform. Eight MR actuator units can result in an over-actuated system with redundancy. With the low-impedance MR actuator device of the present disclosure, the generated force is easily controlled, and if one MR actuator unit fails, the system remains operational.

[0135] Figure 23 is a schematic representation of multiple MR actuation devices 80 used in the robotic arm 230, also referred to as a tandem mechanism. In the configuration, the MR actuation devices 80, 80', and 80" each provide actuation degrees of freedom (DOF) to corresponding co-located joints 1, 2, and 3 to achieve a multiple DOF arm at the end effector (at joint 6). The MR actuation devices 80'", 80'", and 80'""" are remote from joints 4, 5, and 6 and are located within the robotic member 231 (also referred to as a link). The MR actuation devices 80'", 80'", and 80'""" actuate the rotational DOF of joints 4, 5, and 6. Remote actuation can be transmitted using a conveyor belt, cable, shaft, pulley, gear, or any other suitable mechanical linkage arrangement. Remote positioning of the actuation devices 80 ′″, 80 ′″′, and 80 ′″′′ from the joint may result in a reduction in the overall inertia of the arm 230 by locating the weight of the MR actuator closer to the base.

[0136] Figure 24 yes Figure 8Schematic representation of an MR actuation device 80 for controlling a ball screw 241 in FIG. A ball screw 241 is shown, however, any other rotational to linear motion conversion mechanism (e.g., a rack and pinion) or linkage system may be used. The system can be used to control a variety of actuators, including actuators that provide active suspension or steering control. In an embodiment, the MR actuation device 80 has its MR actuator units MRAA and MRAB generate a rotational output on, for example, a spindle to cause translation of the ball screw, or vice versa. Other types of rotational to linear conversion mechanisms are contemplated.

[0137] Figure 25 yes Figure 24 FIG. 1 is a schematic representation of an MR actuation apparatus that actuates a ball screw, wherein the MR fluid clutch devices 10A and 10B can be constructed around the nut (not shown) of the ball screw. This configuration can provide a compact arrangement. Alternatively, the MR clutch devices 10A and 10B can be constructed around the screw 251.

[0138] Figure 26 is a schematic representation of a controller for controlling an MR actuation device 80 with enhanced reliability, and the controller can be used as controller 1 shown above. As an example, the enhanced reliability controller can use four processors distributed across two channels. In an embodiment, the expression processors contain independent processing modules, as opposed to independent hardware processors. Each channel features a controller / monitor arrangement that uses independent controllers to control one motor and one clutch coil. Therefore, in the event of a disagreement between the two processors in a channel, only one set of motors and MR fluid clutch devices (e.g., MR actuator units) is shut down. In this situation, the MR fluid clutch device in the healthy channel is locked, and the motor controls the MR actuator unit like a conventional private motor. Because the motor's inertia, friction, cogging, and gear reduction are reflected at the output, tactile performance is degraded in this mode. In addition, the low mechanical bandwidth available in this degraded mode may prevent backup parallel stability and control enhancement in the event of a control computer (CC) card failure. Despite a single failure, however, system functionality remains available, with the exception of the force sensor. For this reason, Figure 26 The preliminary architecture shown in [1] may include two independent force sensors. With this arrangement, inconsistencies between the force sensor readings may cause the system to passively fail. A slightly different approach using additional force sensing redundancy to maintain closed-loop force control capabilities in the event of a failure of one force sensor may also be implemented.

[0139] refer to Figure 27, the MR actuator device 80 is shown as having two MR actuator units MRAA and MRAB, hypoid or spherical gears 93A, 93B, or similar gears such as worm gears, spiral bevel gears, driving a common output 83. In the embodiment shown, one of the gears 93A is operatively coupled to the first face of the crown gear serving as the common output 83, while the other gear 93B is operatively coupled to the second face of the crown gear serving as the common output 83. Gears 93A, 93B, 93n (if other gears are present) can be coupled to the same face of the output gear 83. A hypoid gear is a spiral bevel gear having an axis of rotation that does not intersect the axis of the output gear 83. The shape of a hypoid gear is a rotating hyperbola. Spiral bevel gears can be used, and the spiral bevel gears have a normal conical shape. Likewise, spherical gears have a spherical profile and can be used. Moreover, Figure 23 A limited number of components are shown, including the reduction gear mechanism. Figures 9 to 13 A variation of the MR actuator device 80 may be used Figure 23 The output 83 in the gears 93A, 93B. Optionally, the rotation axis of the gears 93A and / or 93B is parallel to the rotation axis of the corresponding MR fluid clutch device 10A, 10B.

[0140] A controller 1 may be described as part of a system for driving an output member of a magnetorheological (MR) actuator device having at least two MR actuator units that output a maximum torque T1 and a torque T2, respectively. The system may include: a processor unit; and a non-transitory computer-readable memory communicatively coupled to the processing unit and including computer-readable program instructions executed by the processing unit to: control the two or more MR actuator units to transmit torque to a common output member in a cooperative mode in a common direction, wherein the torque of the common output member in the cooperative mode is greater than the maximum torque T1 or the maximum torque T2; and control the at least two MR actuator units to transmit torque to the common output member in an antagonistic mode in opposite directions, wherein the torque of the common output member in the antagonistic mode is at most equal to the maximum torque T1 or the maximum torque T2.

[0141] In some examples, the system may perform steps or actions such as: controlling the at least two MR actuator units in a cooperative mode includes controlling the slipping of at least one MR fluid clutch device; controlling the at least two MR actuator units in an antagonistic mode includes controlling the slipping of at least one MR fluid clutch device; controlling the at least two MR actuator units to transmit torque in the cooperative mode includes controlling the at least two MR actuator units to transmit a torque at a common output member that is a sum of a maximum torque T1 or a maximum torque T2; for three MR fluid actuator units, with a third MR fluid actuator unit outputting a maximum torque T3, controlling the MR actuator units in the antagonistic mode includes controlling the two MR actuator units to transmit torque to the output member in a common direction; and controlling the third MR actuator unit to transmit torque to the output member in a direction opposite to the direction of the two MR actuator units, wherein the torque of the common output member in the antagonistic mode is at most equal to the maximum torque T1, the maximum torque T2, or the maximum torque T3.

Claims

1. A magnetorheological actuator device comprising: At least two magnetorheological actuator units, each of which includes at least motor, said motor being bidirectional, a magneto-rheological fluid clutch device operatively coupled to the electric machine to receive torque therefrom, the magneto-rheological fluid clutch device being operable to generate a variable amount of torque transmission when subjected to a magnetic field; Output component; a transmission device operatively coupling at least two of the magneto-rheological actuator units to the output member, for the output member to receive torque from the at least two magneto-rheological actuator units, the transmission device having at least one speed reduction mechanism between the magneto-rheological fluid clutch device and the output member for at least one of the at least two magneto-rheological actuator units; a controller for controlling at least two of the magneto-rheological actuator units to drive the output member, the controller being configured to drive the output member at least in an antagonistic mode, in which the at least two magneto-rheological actuator units transmit torque to the output member in opposite directions, and the controller being configured to drive the output member in a cooperative mode, in which the at least two magneto-rheological actuator units transmit torque to the output member in a common direction.

2. The magnetorheological actuator apparatus according to claim 1, comprising at least one speed reduction mechanism between the bidirectional motor and the magnetorheological fluid clutch device for at least one of the at least two magnetorheological actuator units.

3. The magnetorheological actuator device according to claim 1, wherein For at least one of the at least two magnetorheological actuator units, the transmission comprises a spiral bevel gear coupled to the output member.

4. The magnetorheological actuator device according to claim 3, wherein: The rotation axis of the spiral bevel gear is parallel to the rotation axis of the magnetorheological fluid clutch device.

5. The magnetorheological actuator device according to claim 4, wherein The spiral bevel gear is a hypoid gear or a spherical gear.

6. The magnetorheological actuator device according to any one of claims 3 to 5, wherein: The output member is a crown gear.

7. The magnetorheological actuator device according to claim 1, comprising at least three of two of the magnetorheological actuator units.

8. The magnetorheological actuator device according to claim 7, wherein: The controller in the antagonistic mode drives the output member by causing two of the magneto-rheological actuator units to transmit torque to the output member in a common direction and causing a third of the magneto-rheological actuator units to transmit torque to the output member in a direction opposite to the directions of the two magneto-rheological actuator units.

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