Body-aware actuator using magnetorheological fluid clutch apparatus

Abstract

A body-aware magneto-rheological (MR) fluid actuator unit may include a bidirectional motor assembly. A magnetorheological fluid clutch device is connected to the bidirectional motor assembly, the magnetorheological fluid clutch device being controllable to transfer a variable amount of force from the bidirectional motor between the at least two bodies using a reduction mechanism having a reduction ratio greater than 10: 1. The processing unit is configured to: receive data from the sensor; determining, from the data, that the bidirectional motor assembly needs to accelerate or decelerate to a given value to control the relative speed between the input and output of the magnetorheological fluid clutch device, thereby transferring a desired force between the two bodies; the bidirectional motor is controlled to accelerate or decelerate toward the given value, and the magnetorheological fluid clutch apparatus is simultaneously operated to transfer the desired force between the bodies while maintaining the braking torque inertia ratio beyond the haptic limit.

Description

Technical Field

[0001] The present application relates generally to magnetorheological (MR) fluid clutch devices and, more particularly, to bodies, devices, systems, mechanisms, etc. that use such devices to dynamically control motion in robots, active suspension systems, or motion control devices. Background Art

[0002] A mobile robot (e.g., a legged robot) that moves in a desired direction inevitably experiences disturbances or passes through obstacles in its motion, which may also cause impacts or movements in other directions. This undesirable motion is usually caused by disturbances in the medium through which the subject passes. For example, in a biomimetic robot, whether traveling by land, sea, or air, such a robot may encounter surface defects, collisions, waves, cavitation, etc. In the best case, such random defects cause small, undesirable displacements of the subject. This may also cause large impacts and undesirable subject motion or acceleration. For larger events, these random motions and accelerations can trigger instability. In addition, in some cases, particularly violent accelerations may cause the subject to lose control. Moreover, when accelerated or impacted, the subject or actuator may be damaged. Even when stationary, there may be some residual vibrations associated with surface motion (e.g., standing on a mobile platform). In motion, such residual vibrations can cause wear of components.

[0003] The main purpose of the actuation system of the body is to provide control between the medium (e.g., a surface) and the body in order to move a portion of the body relative to the surface and maintain or control the stability of the body, thereby providing a path for transmitting forces from the contact points to the body. In applications where the body is a legged or wheeled body, the contact points are also used to change the speed or direction of the body. Among legged bodies, some common examples of robots are often referred to as biomimetic robots, such as the MIT Cheetah or the Boston Dynamics Atlas and Spot.

[0004] In a legged robot, each leg assembly is connected to the robot chassis by one or more links. A link is defined as a substantially rigid member that joins with other links or bodies by one or more joints at the ends that allow a specific motion to occur. These links help transfer the motion (or path) from the actuator to the body's environment as the body moves over a surface to induce motion. Some compliance and damping may also be actively incorporated into the links to partially decouple the actuator from the environment to improve stability or protect from high impact loads.

[0005] The design of proprioceptive actuator systems for actuating the legs or limbs of a robot typically represents a compromise between torque density, bandwidth required to control the robot, backdriveability, inertia, and heat generation.

[0006] Typically, kinematically induced leg reaction forces are generated by the interaction between the leg and the surface, and / or by inertial forces generated by the movement of the leg mass. The reaction forces generated between the contact points of the leg and the surface or road are transmitted to the body via the linkage and actuation system.

[0007] In biomimetic robotics applications, controlled forces are introduced in the suspension between the mass of the robot body and the actuators in contact with the surface, for example by hydraulic or electric actuators. Actuator mass is the equivalent mass that reproduces the inertial forces generated by the motion of the parts of the robot that are not carried by the actuators. For a legged robot, this mainly includes the foot assembly, any mass springs and dampers associated with the foot assembly, and some portion of the linkage mass. Body mass is the mass of the parts of the robot that are carried by the actuation system, including the body or chassis. The actuation system can introduce forces that are independent of the relative body motion and velocity.

[0008] In active suspension applications in vehicles, controlled forces are introduced into the suspension between the sprung mass of the vehicle body and its occupants and the unsprung mass of the wheel assemblies, for example, by hydraulic or electric actuators. The unsprung mass is the equivalent mass that reproduces the inertial forces generated by the motion of the components of the vehicle that are not carried by the suspension system. This primarily includes the wheel assemblies, any mass dampers associated with the wheel assemblies, and some portion of the mass of the suspension linkage. The sprung mass is the mass of those components of the vehicle that are carried by the suspension system, including the vehicle body. Active suspension systems can introduce forces that are independent of relative wheel motion and velocity.

[0009] Some robotic systems or active suspension systems rely on electro-hydraulic actuation based on a pump and valve system that regulates the pressure of the hydraulic fluid in a conventional hydraulic piston. Electro-hydraulic methods are typically torque-intensive, but do not have sufficient bandwidth to cope with the spectrum of all disturbances caused, and are therefore inefficient. To address this problem, some systems include a series elastic actuation system that utilizes a spring in series with a high reduction ratio motor. A high reduction ratio motor is a more efficient system, but may result in an increase in reflected inertia. The introduction of the spring increases the compliance of the actuator in order to reduce the impact force caused by the high inertia (e.g., when the foot contacts the ground or when the wheel hits a pothole), but also reduces the natural frequency of the system, providing a smaller mechanical bandwidth, and reducing the alternative actuation system using a quasi-direct drive method that combines a high torque density motor with a low transmission ratio. From a performance point of view, this method provides efficient (transportation cost) movement at high speeds. From the actuator point of view, this method is not torque-intensive due to the low transmission ratio, but due to the increased copper loss of the larger motor, this method still has a relatively high inertia and is not as effective as the high reduction ratio method.

[0010] Magnetorheological (MR) fluid actuators can solve most of the problems of the prior art. However, such magnetorheological fluid actuator systems have the disadvantage that they are generally more complex and costly compared to standard actuation systems due to the large number of components used.

[0011] For this reason, there remains a need for a more economical active proprioceptive actuation system that operates at a relatively high performance compared to prior art systems. Summary of the invention

[0012] It is an object of the present disclosure to provide a new active motion control system using a magnetorheological fluid clutch device.

[0013] Another object of the present disclosure is to provide a method and system for increasing the transmission ratio of a proprioceptive actuator without reducing the controllability of such actuator in the direction of motion due to the reflected inertia of such actuator.

[0014] It is another object of the present disclosure to provide a new robotic actuator utilizing a magnetorheological fluid clutch device.

[0015] Yet another object of the present disclosure is to use such a system in a legged robot or a humanoid robot.

[0016] Yet another object of the present disclosure is to use such a system in a vehicle or mobile device active suspension system.

[0017] Therefore, according to a first aspect of the present disclosure, a proprioceptive magnetorheological (MR) fluid actuator unit is provided, comprising: a bidirectional motor assembly; a reduction mechanism having a reduction ratio greater than 10:1; a magnetorheological fluid clutch device connected to the bidirectional motor assembly, the magnetorheological fluid clutch device being controllable to transfer a variable amount of force from the bidirectional motor between at least two bodies using the reduction mechanism; at least one sensor for providing data indicating a state of at least one body; a processing unit; and a non-transitory computer-readable memory communicatively connected to the processing unit and comprising computer-readable program instructions that can be implemented by the processing unit for performing the following operations: receiving data from at least one sensor; determining from the data that the bidirectional motor assembly should be accelerated or decelerated to a given value to control the relative speed between the input and output of the magnetorheological fluid clutch device, thereby transferring a desired force between the two bodies; controlling the bidirectional motor to accelerate or decelerate toward the given value; and simultaneously operating the magnetorheological fluid clutch device to transfer the desired force between the bodies while maintaining the braking torque-to-inertia ratio exceeding the tactile limit.

[0018] According to further the first aspect, for example, the first body is a mass body and the second body is a structure body.

[0019] Furthermore, according to the first aspect, for example, the mass body is connected to the structure via a spring.

[0020] Furthermore, according to the first aspect, for example, the mass body is controlled to implement an active suspension.

[0021] Furthermore, according to the first aspect, for example, the main body is a link of a robot interconnected by a joint.

[0022] Furthermore, according to the first aspect, for example, the robot is a robot having a limb, and the link is a part of the limb.

[0023] Furthermore, according to the first aspect, for example, at least two bodies are interconnected by a rotary joint.

[0024] Still further, according to the first aspect, for example, the speed reduction mechanism includes a rotation-to-linear converter for the proprioceptive magnetorheological fluid actuator unit to transmit the translational force between the bodies.

[0025] Still further, according to the first aspect, for example, the speed reduction mechanism includes a rotation-to-rotation arrangement for the body-sensing magnetorheological fluid actuator unit to transmit torque between the bodies.

[0026] Still further, according to the first aspect, for example, computer readable program instructions may be implemented by a processing unit to cause a magnetorheological fluid clutch device to slip when a brake torque to inertia ratio exceeds a tactile limit.

[0027] Furthermore, according to the first aspect, for example, for the proprioceptive magnetorheological fluid actuator unit, when the torque is in Nm, the tactile limit is in Nm / kgm 2 When the unit is equal to torque / (9×10 -6 ×Torque 1.66667 ).

[0028] Furthermore, according to the first aspect, for example, for the actuator unit, when the torque is 75 Nm, the tactile limit is 6300 N.m / kgm 2 .

[0029] Furthermore, according to the first aspect, for example, the magnetorheological fluid clutch device has at least 1×10 6 Nm / kg.m 2 Torque to inertia ratio.

[0030] Furthermore, according to the first aspect, for example, the reduction mechanism has a contact ratio of at least 2 between the torque transmitting elements.

[0031] Furthermore, according to the first aspect, for example, the speed reduction mechanism includes a plurality of load paths.

[0032] Furthermore, according to the first aspect, for example, the speed reduction mechanism is a planetary gear mechanism having at least two planetary gears.

[0033] According to another aspect of the present disclosure, a system for operating a magnetorheological (MR) actuator unit between subjects is provided, comprising: a magnetorheological actuator unit including a bidirectional motor assembly, the bidirectional motor assembly operating within a first frequency range, and a magnetorheological fluid clutch device connected to the bidirectional motor assembly to apply a variable amount of force from the bidirectional motor between at least two subjects, the magnetorheological fluid clutch device operating within a second frequency range, the second frequency range being higher than the first frequency range; at least one sensor for providing data indicative of a state of at least one subject; a processing unit; and a non-transitory computer readable memory, communicating with the processing unit; is coupled to a processing unit and includes computer readable program instructions that can be implemented by the processing unit to perform the following items: receive data from at least one sensor; determine from the data that the bidirectional motor assembly should be accelerated or decelerated to control the amplitude and direction of the relative velocity between the input and output of the magnetorheological fluid clutch device, thereby transmitting a desired force between the bodies; control the bidirectional motor to accelerate or decelerate towards a given value within a first frequency range and at the same time reduce the torque transmission from the magnetorheological fluid clutch device during disturbances caused by impact or contact with the environment, during which the torque transmission does not correspond to the desired force that can be achieved only by control of the motor.

[0034] According to another aspect, a system for operating a proprioceptive actuator between a body and an actuator is provided, comprising: a bidirectional motor; a magnetorheological (MR) fluid clutch device, coupling the bidirectional motor to the body to apply force from the bidirectional motor to the actuator; at least one sensor for providing data indicating a state of a mass body and / or a state of a structure; a processing unit; and a non-transitory computer-readable memory, communicatively coupled to the processing unit and comprising computer-readable program instructions, which can be implemented by the processing unit for: receiving data from at least one sensor; determining a desired torque amplitude generated by the bidirectional motor from the data; keeping the bidirectional motor turned on when the desired torque amplitude is below a torque amplitude threshold to store mechanical momentum in a rotating component of the actuator, and activating the magnetorheological fluid clutch device when the desired torque amplitude is above the torque amplitude threshold to use the stored mechanical momentum.

[0035] According to yet another aspect, a system for operating a robotic actuator between two bodies is provided, comprising: a bidirectional motor operating within a first frequency range; a magnetorheological (MR) fluid clutch device coupling the bidirectional motor to the body to apply force from the bidirectional motor to the actuator, the magnetorheological fluid clutch device operating within a second inertia range, the second inertia range being less than the first inertia range; at least one sensor for providing data indicating a state of a mass body and / or a state of a structure; a processing unit; and a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions implementable by the processing unit for: receiving data from at least one sensor; determining a switching direction of the bidirectional motor from the data; and simultaneously controlling the bidirectional motor to reduce torque transfer from the magnetorheological fluid clutch device when the force is not at a desired level. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of a general magnetorheological (MR) fluid clutch device incorporating features of the present disclosure;

[0037] Figure 2 According to one embodiment Figure 1 A schematic cross-sectional view of a magnetorheological fluid clutch device;

[0038] Figure 3 is an illustration of a magnetorheological fluid actuator using a single motor and a single magnetorheological fluid clutch device;

[0039] Figure 4 is an illustration of a magnetorheological fluid actuator using a single motor and two magnetorheological fluid clutch devices;

[0040] Figure 5is a diagram of two magnetorheological fluid actuators arranged in parallel paths;

[0041] Figure 6 is a schematic diagram of a variation of a rotary magnetorheological fluid actuator;

[0042] Figure 7 yes Figure 6 Detailed illustration of a rotary magnetorheological fluid actuator;

[0043] Figure 8 is a schematic diagram of a variation of a linear magnetorheological fluid actuator using a rack and pinion coupled to a single motor and a single magnetorheological fluid clutch device;

[0044] Fig. 9 is a graph showing positive and negative torque transfer using a magnetorheological fluid clutch;

[0045] Fig.10 is a schematic diagram of an electromagnetic actuator of the prior art;

[0046] Fig.11 is a schematic diagram of a proprioceptive electromagnetic actuator using a magnetorheological fluid clutch device according to the present disclosure;

[0047] Fig.12 is a graph showing the torque to inertia ratio of the actuator brake and the torque to mass ratio of the brake;

[0048] Fig.13 is a table showing mass and inertia parameters of quasi-direct drive and magnetorheological fluid actuators;

[0049] Fig.14 is a prior art collaborative robot, showing its typical dimensions;

[0050] Fig.15 It is a schematic diagram of a single degree of freedom dynamic model with concentrated parameters;

[0051] Fig.16 is a graph showing no-load acceleration using a one-dimensional model of a quasi-direct drive and a magnetorheological fluid actuator with a disk or drum;

[0052] Fig.17 is a graph showing torque cost of a quasi-direct drive and a magnetorheological fluid actuator;

[0053] Fig.18 It is a magnetorheological fluid clutch device. Fig.11 A cross-sectional view of an embodiment of a proprioceptive electromagnetic actuator;

[0054] Fig.19is a performance comparison table of prior art proprioceptive sensing quasi-direct drive actuator performance and the performance of a proposed proprioceptive sensing actuator using a magnetorheological fluid clutch device;

[0055] Fig. 20 is a schematic diagram of a lumped parameter single degree of freedom dynamic model using a linear actuator at one joint and a rotary actuator at a second joint;

[0056] Fig.21 is a schematic diagram of a vehicle suspension equipped with a proprioceptive electromagnetic actuator using a magnetorheological fluid clutch device according to the present disclosure;

[0057] Fig. 22 is a table and graph representing scaling laws for haptic limits as a function of actuator torque; and

[0058] Fig.23 is a schematic diagram of a proprioceptive electromagnetic linear actuator using a magnetorheological fluid clutch device according to the present disclosure. DETAILED DESCRIPTION

[0059] With reference to the accompanying drawings, and more particularly with reference to Figure 1 , shows a magnetorheological (MR) fluid clutch device 10 that is configured to provide a mechanical output force based on a received input current. Thus, each device, system, apparatus, etc. described herein and having one or more magnetorheological fluid clutch devices 10 can be operated by a controller 10' based on a sensor 10" to provide a suitable input current, which sensor can receive data from any component of the device, system, apparatus, etc. The controller 10' may include: one or more processing units; and a non-transitory computer-readable memory, communicatively coupled to the processing unit and including computer-readable program instructions that can be implemented by the processing unit for operating the system, device, apparatus, etc. described herein. The magnetorheological fluid clutch device 10 is shown as a type having a co-linear input shaft and an output shaft. However, the concepts described herein can be applied to other configurations of magnetorheological fluid clutch devices, such as some configurations having an input or output housing / casing for an output shaft or an input shaft, etc. The principles shown here will be performed using a drum-type magnetorheological fluid clutch device, but can also be applied to a disc-type magnetorheological fluid clutch device. One or more magnets can also be introduced into the magnetic circuit so that the magnetorheological fluid clutch device 10 provides torque when it is not powered.

[0060] The magnetorheological fluid clutch device 10 can provide an output force in response to an input current received from an operator to transmit an input force and an output force based on the magnetization level of the magnetizable portion in the magnetic circuit when there is no input current. The exemplary magnetorheological fluid clutch device 10 can have a stator 10A, through which the magnetorheological fluid clutch device 10 is connected to a structure. The magnetorheological fluid clutch device 10 has a driven member 11 and a driving member 12 separated by a gap filled with a magnetorheological fluid, as explained below. The driving member 12 can receive rotational energy (torque) from a power device such as an electric motor, with or without a transmission device such as a reduction gearbox.

[0061] According to one embodiment, the driving member 12 can be mechanically connected to the power input, and the driven member 11 can be mechanically connected to the power output (i.e., force output, torque output). The stator 10A, the driven member 11 and the driving member 12 can be interconnected by bearings 12A and 12B. In the illustrated embodiment, the bearing 12A is located between the stator 10A and the driving member 12, and the bearing 12B is located between the driven member 11 and the driving member 12. A seal 12C can also be provided at the interface between the driven member 11 and the driving member 12 to retain the magnetorheological fluid between the driven member 11 and the driving member 12. In addition, the seal is configured to prevent the magnetorheological fluid from reaching the bearing 12B or leaking from the device 10.

[0062] As reference Figure 2 As shown, the drum is positioned circumferentially around the axis of rotation CL. Therefore, some supports need to extend generally radially to support the drum arranged along its circumference. According to one embodiment, reference Figure 2 , a low magnetic permeability input drum support 13 (also referred to as a radial wall) protrudes radially from the shaft of the drive member 12. The input drum support 13 can be connected to an input rotor 14 that defines a housing or casing of the magnetorheological fluid clutch device 10. The input rotor 14 can therefore be rotatably connected to the driven member 11 via a bearing 12B. In one embodiment, the input rotor 14 has an input rotor support 14A that forms a housing for the bearing 12B. According to one embodiment, the input rotor support 14A is an integrally formed part of the input rotor 14 and can be manufactured as a single piece. However, this is not desirable because ideally the input rotor support 14A is made of a low magnetic permeability material and the input rotor is made of a high magnetic permeability material. As another embodiment, Figure 2As shown, the input rotor support 14A may be defined by an annular wall that is manufactured separately from the rest of the input rotor 14, but the two are interconnected so as to rotate simultaneously. Thus, the shaft of the drive member 12, the input drum support 13, and the input rotor 14 rotate simultaneously. In one embodiment, it is contemplated that the housing of the magnetorheological fluid clutch device 10 is part of the stator 10A or the driven member 11.

[0063] The input drum support 13 can support a plurality of concentric annular drums 15, also referred to as input annular drums. The input annular drums 15 are fixed to the input drum support 13. In one embodiment, concentric circular channels are defined (e.g., machined, cast, molded, etc.) in the input drum support 13 for inserting the drums 15 therein. A tight fit (e.g., press fit), adhesive, and / or radial pins can be used to secure the drums 15 to the input drum support 13. In one embodiment, the input drum support 13 is integrally connected to the shaft of the drive member 12, whereby the various components of the drive member 12 rotate simultaneously when receiving drive from a power source.

[0064] The driven member 11 is represented by an output shaft which is also configured to rotate about the axis CL. The output shaft may be coupled to various mechanical components which receive a transmitted power output when the clutch device 10 is actuated to transmit at least some of the rotational power input.

[0065] The driven member 11 also has one or more concentric annular drums 16 (also referred to as output drums) mounted to an output drum support 17. The output drum support 17 may be an integral part of the output shaft, or may be mounted thereon for simultaneous rotation. The annular drums 16 are spaced apart so that the groups of output annular drums 16 fit in an annular space between the input annular drums 15 in an interlaced manner. When either of the driven member 11 and the driving member 12 rotates, there is no direct contact between the annular drums 15 and 16 due to the concentricity of the annular drums 15 and 16 about the axis CL.

[0066] according to Figure 3 , a magnetorheological fluid actuator 20 (also referred to as a magnetorheological fluid actuator unit) is shown as having a magnetorheological fluid clutch device 10 of the type described above. The actuator consists of a motor 21, an input gearbox 22, a magnetorheological fluid clutch device 10, an output gearbox 23 and an output portion 24, but one or both gearboxes may be optional. Moreover, any magnetorheological fluid actuator 20 may be supplemented with a sensor to indicate the position (e.g., a position sensor), acceleration (e.g., an acceleration sensor), or torque / force (e.g., a torque or force sensor) generated by the magnetorheological fluid actuator 20. In one variation, in a basic configuration, a magnetorheological fluid actuator such as shown as 20 has a motor 21 and a magnetorheological fluid clutch device 10.

[0067] Figure 4 Another type of magneto-rheological fluid actuator is shown, which includes a single motor, an input gearbox 22, two magneto-rheological fluid clutch devices 10A and 10B, which rotate in opposite directions and exert reaction forces on the output portion 24, each through a gearbox 23A and 23B.

[0068] Figure 5 Another type of magnetorheological fluid actuator is shown. The magnetorheological fluid actuator is composed of two magnetorheological fluid actuators. The two magnetorheological fluid actuators are similar to Figure 3 The magnetorheological fluid actuators in the embodiment of the present invention are connected in parallel to apply force on a single output portion 24. The first actuation branch is composed of a motor 21A, an input gearbox 22A, a magnetorheological fluid clutch device 10A, and an output gearbox 23A driving the output portion 24. The second actuation branch is composed of a motor 21B, an input gearbox 22B, a magnetorheological fluid clutch device 10B, and an output gearbox 23B driving the same output portion 24. It should be noted that for simplicity, the explanation provided is for the control of one degree of freedom, but multiple magnetorheological fluid actuators can be used to control multiple degrees of freedom of the body. In addition, multiple magnetorheological fluid clutch devices can share the same power source, such as Figure 3 , where both magnetorheological fluid clutch devices 10 receive actuation power from a single motor 21 via a transmission 22. The transmission 22 is shown as having a gearbox, but pulleys and belts may also be used. However, the transmission 22 may also be of other types, such as chains and pinions, to name a few. Other devices can be used as variable force sources or biasing members.

[0069] The combination of a variable power source and a magnetorheological fluid clutch device 10 provides the advantages of a hybrid system, where one device or the other (or both simultaneously) can be controlled depending on the operating conditions. In embodiments where the power source is a motor, the motor speed, available torque, and torque delivered by the magnetorheological fluid clutch device 10 can be controlled. This can increase the potential operating points while increasing the overall performance or efficiency of the system. The output of the magnetorheological fluid clutch can be decoupled from the input. In some applications, this may be useful to decouple the inertia from the input so as not to affect the response time of the output.

[0070] refer to Figure 6 and Figure 7 , showing Figure 5The structure uses output reduction transmission devices 86 (e.g., bevel gears) and 86', and the output reduction mechanisms 86 and 86' each have output shafts 87 and 87' connected to a single actuator output member 88, and a connector connected to a single rotary output member 88. A rotary output is shown here, but it can also be replaced by a linear type mechanism (e.g., ball screw, roller screw, rack and pinion, lever arm). Described in International Patent Application Publication No. WO2021 / 155478A1 Figure 6 and Figure 7 The embodiments of the present invention are incorporated herein by reference. Figure 6 and Figure 7 Embodiments of or other embodiments described herein may also be used as part of a robotic joint.

[0071] Figure 8 A single-motor single-clutch actuator system is shown. A single magnetorheological fluid clutch device 10 is used, wherein a pinion 203 is provided on a structural link 201, and by applying a force on a rack portion 204, a braking or actuation of the movement of the structural link 201 in a non-biased direction is provided, thereby acting as a magnetorheological brake or actuator. Similarly, other types of linear mechanisms (e.g., ball screws, roller screws, racks and pinions, lever arms) can be used. In one embodiment, the motor 21 can be a bidirectional motor. In such a magnetorheological motion control system, the motor 21 and the magnetorheological fluid clutch device 10 are usually required to be reversed, also called changing or switching direction (e.g., CW to CWW or vice versa, X translation to -X translation or vice versa). For example, an arrangement includes a motor 21, an optional input reduction mechanism 84 (embedded and not shown) and a magnetorheological fluid clutch device 10, wherein the input member 12 rotates at a different speed than the output member 11 to provide a slip state that decouples the input inertia from the output. The direction of slip within the magnetorheological fluid clutch device 10 controls the direction (positive or negative) of the output torque. When the magnetorheological fluid clutch device 10 slips and changes direction, a slip direction reversal may occur, for example: A) when the input member 12 initially rotates faster than the output member 11 and transitions to a state where it rotates slower than the output member 11, from positive torque to negative torque; B) when the input member 12 initially rotates slower than the output member 11 and transitions to a state where it rotates faster than the output member 11, from negative torque to positive torque.

[0072] Real-time switching of slip direction can allow the controller to maximize torque output and controllability. In the case of an arrangement with a single motor 21 and a single magnetorheological fluid clutch device, for example Figure 8As shown, this may mean that the magnetorheological fluid actuator unit (i.e., a motor 21 and a magnetorheological fluid clutch device 10) needs to be reversed to switch. This real-time switching mode of the magnetorheological fluid actuator requires the clutch input speed member 12, ω c,1 Increase or decrease so that relative to the output speed ω a If the transition is too slow, controllability may potentially be lost during the transition.

[0073] You can use ω c,2 -ω c,1 =2Δω represents the speed difference during reversal, assuming that a Δω slip is required in the magnetorheological fluid clutch device 10 to produce torque in the direction of Δω. Assuming constant acceleration and ignoring the motor electrical response, the slip reversal time can be given by the gear motor acceleration limit:

[0074]

[0075] To make the reversal noticeable, the required motor reversal time can be smaller than the required torque time response of the actuator:

[0076] Δt<<τ r

[0077] The time response of the actuator is related to the blocking force bandwidth (-3dB desired applied force command) of the actuator in Hz by:

[0078]

[0079] Therefore, the minimum gearmotor acceleration required for imperceptible slip for a given application is:

[0080] α gm >>5.7Δωf 3dB

[0081] If Δω = 10i (in RPM, or Δω = 1.05i in rad / s), and if the maximum human-perceivable force bandwidth is 20 Hz, the acceleration of the gear motor can be

[0082] For imperceptible shifting, the shifting should be done under constant torque conditions where acceleration is maximum. In addition, the input reduction ratio 84 can be kept as low as possible because Therefore the selection of the motor / input reduction ratio 84 is critical for seamless slip direction changes. p =4:1 Input reduction ratio 84 connection, given motor torque inertia ratio Down to And can become perceptible. On the contrary, other motors can be input with a reduction ratio of 84r p = 1:1 operation, and has The torque to inertia ratio is within the range, so there is strong potential for seamless transitions. The numbers used here are for general illustration purposes only and may not necessarily reflect actual device values.

[0083] As shown in this example, the minimum gear motor dynamics cannot always match the system requirements. Figure 4 ) always maintains opposition and does not exhibit reversal events because there is always a magnetorheological fluid clutch device 10 slipping in each direction relative to the output, thereby providing optimal motion control performance.

[0084] A motion control system (such as a motor 21 and a magnetorheological fluid clutch device 10) is used only Figure 8 ), and reconfigurable motion control systems using multiple motor / clutch chains that can switch between antagonistic and combined operations (e.g. Figure 6 ) need to inevitably face a reversal event and is therefore potentially hindered by the combination of the dynamic characteristics of the motor 21 and the input reduction mechanism 84.

[0085] The present disclosure describes a method for minimizing controllability loss during impact and reversal when the dynamics of the combination of the motor 21 and the input reduction mechanism 84 are slower than the motion system requires.

[0086] Fig.10 Schematic diagrams of prior art electromagnetic (EM) actuators are shown. A) A direct drive (DD) actuator, B) a high reduction ratio actuator (HD), C) a quasi direct drive (QDD), and D) a series elastic actuator (SEA) are shown. The quasi direct drive actuator C) has a high torque density motor, a low ratio transmission, and a low inertia output. For electromagnetic actuators, the impact mitigation factor (IMF) is a factor that can be said to quantify the normalized inertial impedance of a floating robot, capturing the effect of the actuator design to reduce impulse forces during impact. For such a quasi direct drive actuator, it can be said that the optimal actuator for a given mass may include a motor with the largest gap radius within the available space, and the smallest transmission ratio required based on the torque specification.

[0087] Fig.11 is a schematic diagram of a proprioceptive electromagnetic actuator using a magnetorheological fluid clutch device 11 according to the present disclosure. In the prior art proprioceptive electromagnetic actuator, for example Fig.10C) The quasi-direct drive proposed in the transmission ratio can be limited so that too much force is not generated when the end effector impacts the surface, and the transmission ratio is usually less than 10:1. When the actuator is oversimplified, the reflected inertia of the actuator is proportional to the inertia of the motor and the square of the gearbox ratio. For a given motor inertia, increasing the gearbox ratio will increase the torque proportionally, but increase the reflected inertia to the square of the reflected inertia. Therefore, the torque / inertia ratio will decrease faster than the increase in inertia. The inertia of the known system is an important factor in limiting the impact force of the end effector on the surface or object. For a given end effector speed, the lower the inertia of the end effector and the reflected inertia of the motor and gearbox combination, the lower the impact force will be. It may be advantageous to limit this inertia. Because the inertia increases faster than the torque when the transmission ratio increases, there may be a motivation to limit the gearbox ratio to limit the inertia of the system, thereby compromising the increase in torque ratio. However, the introduction of a magnetorheological fluid clutch device 10 in the chain may help achieve an increased torque density without increasing the total inertia at the end effector. It is known that magnetorheological fluid clutch devices, such as 10 in various embodiments herein, have a lower inherent inertia per unit torque than motors. Typically, for a given torque, the torque / inertia of the magnetorheological fluid clutch device will be five times the torque / inertia of the motor. Thus, for a given torque and gearbox ratio, the magnetorheological fluid clutch device can reflect an inertia that is approximately 25 times smaller than at the end effector. The smaller inertia reflected at the output can provide some advantages, but this can also involve a higher gear ratio between the motor and the end effector.

[0088] Thereafter an analysis is derived to understand the effect of the transmission ratio on the actuator performance and to compare quasi-direct drive actuators and magnetorheological fluid actuators, i.e., e.g. Fig.11 Or one of the other combinations of motor and magnetorheological fluid clutch device. Actuator torque-to-mass ratio τ b and torque-to-inertia ratio α b can be expressed in terms of the motor, clutch (if present) and transmission properties such that:

[0089] Torque-to-mass ratio (τ) of quasi-direct drive actuator b ) is given by:

[0090]

[0091] Among them, τ m is the motor torque-to-mass ratio, K τ is the gear mass constant, i is the transmission ratio, and η is the gear transmission efficiency, such that:

[0092] η(i)=0.9519-0.02489ln(i)-3.24x10 -5 i (2)

[0093] The torque-to-mass ratio of a magnetorheological fluid actuator is given by:

[0094]

[0095] Among them, τ m is the motor torque-to-mass ratio, τ c is the clutch torque-to-mass ratio, K τ is the gear mass constant, i is the transmission ratio, and η is the gear transmission efficiency.

[0096] The torque-to-inertia ratio of a quasi-direct drive actuator is given by:

[0097]

[0098] Among them, α m is the motor torque-to-inertia ratio, K α is the gear transmission inertia constant, i is the transmission ratio, and η is the gear transmission efficiency.

[0099] The torque-to-inertia ratio of a magnetorheological fluid actuator is given by:

[0100]

[0101] Among them, α c is the clutch torque-to-inertia ratio, K α is the gear transmission inertia constant, i is the transmission ratio, and η is the gear transmission efficiency.

[0102] Fig.12 The torque-to-mass ratio and torque-to-inertia ratio are shown as a function of the actuator gear ratio for a quasi-direct drive actuator and a magneto-rheological fluid actuator. The graph shows the actuator brake torque-to-inertia ratio (left), and brake torque-to-mass ratio (right) on a logarithmic scale. The curves for the magneto-rheological fluid actuator are for a magneto-rheological fluid clutch device using drum (lower curve) and disc (upper curve) shear surfaces. The values ​​are expressed using Fig.13 The parameters listed in are calculated from . These parameters represent experimentally demonstrated state of the art values ​​for quasi-direct drive actuators and magnetorheological fluid actuators.

[0103] look Fig.12 , the quasi-direct drive curve shows 3 points on the left. These are practical design limits within the range of 75Nm output torque, such as the Cheetah actuator (7.5:1 ratio) and the humanoid actuator (12:1). The middle point is the average of the two and sets the horizontal dashed line, which indicates that it can be set to 6300N.m / kgm 2 The acceptable torque-inertia limit.

[0104] The magnetorheological fluid actuator is related to the quality of its magnetorheological fluid clutch device. Two designs are shown, a strong and durable drum clutch and a new high performance disc clutch. The middle point between the two is again the technical average. The magnetorheological fluid clutch device 10 used in the proprioceptive magnetorheological fluid actuator is made by making it have at least 1.5×10 6 Nm / kg.m 2 The torque-to-inertia ratio can help the actuator behave as having a high braking torque-to-inertia ratio. This ratio of the magnetorheological fluid clutch device 10 can be achieved in different ways, such as by adjusting the total area of ​​the shear surface, the size of the drum or disc (disc), the thickness and weight of the components. Another factor that can contribute to the high braking torque-to-inertia ratio of the proprioceptive magnetorheological fluid actuator is to provide a suitable transmission device. For example, the reduction mechanism in the proprioceptive magnetorheological fluid actuator unit of the present disclosure can have a low-inertia gear transmission technology, which has more than one contact point between the gears (i.e., a contact ratio of at least 2, which is the average number of gear teeth that contact each other when the gears are in operation). More than one contact point can be achieved by using gears with more than one contacting tooth (e.g., bevel gears, internal gears, helical gears, or spiral gears) and / or by using a gear train arrangement (e.g., an epicyclic gear train) with more than one contacting gear. Therefore, the combination of these design factors can help provide a high torque density to the proprioceptive magnetorheological fluid actuator unit, despite the high reduction ratio.

[0105] It can be seen that the magnetorheological fluid actuator can use a transmission ratio of about 190:1 while still meeting 6300N.m / kgm 2 threshold. This is about 10 times higher than a quasi-direct drive actuator. The benefit is that for the same dynamic performance (torque-inertia), a magnetorheological fluid actuator is lighter than a quasi-direct drive actuator (e.g. 2.4 times 70 vs 170 N.m / kg) due to the higher gear ratio associated with the magnetorheological fluid actuator.

[0106] look Fig.12 Green arrows in: A) Start from the left. The MR fluid actuator requires a 30:1 gear ratio to match the torque-to-mass ratio of a practical quasi-direct drive by a ratio of about 10:1. At 30:1, the torque-to-inertia ratio of the MR fluid actuator is about 6300 N.m / kgm 2 The limit is 15.9 times higher, resulting in high mass force capabilities similar to the best tactile receptors. B) Starting from the right. The quasi-direct drive actuator requires a 60:1 gear ratio to match the torque-to-mass ratio of the magnetorheological fluid actuator using 190:1. At 60:1, the torque-to-inertia ratio of the quasi-direct drive actuator is 6300 N.m / kgm 2The limit is 6.3 times lower, destroying the quality of the force to reach the level of conventional gear motors.

[0107] This analysis shows that high torque-to-mass ratios and high torque-to-inertia ratios are difficult to achieve with current quasi-direct drive technology. Better performance can be achieved with magnetorheological fluid actuators, where a clutch is introduced to remove the motor inertia from the picture, allowing for higher transmissions. In the prior art, at ratios between 30:1 and 190:1, magnetorheological fluid actuators exhibit higher torque-to-mass and torque-to-inertia ratios than quasi-direct drive actuators, which are limited to ratios of about 10:1.

[0108] As a result, despite the addition of an extra component to the actuator system, namely the magnetorheological fluid clutch device, and thus increased weight, this actually results in a lighter actuator with lower inertia when the appropriate gear ratio is used.

[0109] The impact of both higher torque-to-mass ratio and higher torque-to-inertia ratio on a quasi-direct drive actuator over the robotic system is analyzed on a typical collaborative robot.

[0110] Fig.14 The robot arm shown represents an exemplary collaborative robotic system. The kinematics of its three proximal joints connected by links a1, a2, and a3 are also representative of other typical collaborative robotic systems, such as humanoid robots (shoulder and hip) and animal robots (eg, MIT Cheetah).

[0111] The three proximal joints are also the most demanding in terms of dynamic capabilities. By considering only one link (e.g. Fig.15 As shown in Figure 2, a simplified, concentrated parameter, single degree of freedom dynamic model for the first three joints can be derived. Fig.14 The robot arm uses joints with the same rated braking torque T b , mass m and inertia I. The connecting rod is massless and its length is taken as the average length of the first three joints (a1, a2, a3), which is 320 mm, as Fig.14 shown.

[0112] The performance measure of the system dynamics including the actuator inertia and mass effects is the no-load acceleration of the connecting rod, i.e., when the torque T b The maximum angular acceleration θ of the connecting rod when applied to joint i without external load is:

[0113] T b =(I+mr 2 )θ¨ (6)

[0114] It simplifies to:

[0115]

[0116] where α b =T b / I is the actuator brake torque to inertia ratio, and τ b =T b / m is the actuator braking torque-to-mass ratio.

[0117] Fig.16 The no-load acceleration versus transmission ratio for a one-dimensional model using a quasi-direct drive actuator and a magnetorheological fluid actuator is plotted in FIG. Fig.13 The values ​​in the table are again used to calculate the actuator brake torque to inertia ratio and brake torque to mass ratio.

[0118] The maximum no-load acceleration of the quasi-direct drive is 25:1, which is due to the large torque-to-inertia ratio (according to Fig.12 ) but cannot be achieved in practice. At the current ratio limit of about 10:1, the quasi-direct drive has 700 rad / s 2 Maximum acceleration around.

[0119] The magnetorheological fluid actuator has a maximum no-load acceleration of 150:1, which can be used with an acceptable torque-to-inertia ratio (according to Fig.12 ) is achieved at the same time. At 150:1, the magnetorheological fluid actuator has a maximum no-load acceleration of between 1200 and 1500, depending on the clutch technology. The maximum no-load acceleration of the magnetorheological fluid actuator is therefore approximately twice that of the quasi-direct drive actuator.

[0120] The crossover point where the MR fluid actuator shows better no-load acceleration than the quasi-direct drive is at the 30:1 point, which is the same threshold where the torque-to-mass ratio of the MR fluid actuator equals the torque-to-mass ratio of the quasi-direct drive actuator (according to Fig.12 ).

[0121] The ability to use higher gear ratios has a direct impact on energy consumption. Fig.17 As shown in the design simulation in , the quasi-direct drive has a power consumption of about 4W / Nm at its extreme transmission ratio of 10:1. In contrast, at a transmission ratio of 150:1, the magnetorheological fluid actuator has a power consumption of 0.6W / Nm when the magnetorheological fluid clutch is locked, and a power consumption of 2W / Nm when the magnetorheological fluid clutch is slipping. This reduces the power consumption by about 6.7 times when the clutch is locked, and by about 2 times when the clutch is slipping.

[0122] Thus, when power needs to be supplied to the clutch coil, and when power is lost when the magnetorheological fluid clutch device slips, the magnetorheological fluid actuator can counterintuitively exhibit lower power consumption than a quasi-direct drive actuator.

[0123] The optimum overall transmission ratio for a proprioceptive actuator using the magnetorheological fluid clutch device 10 will then be higher than that of a quasi-direct drive, and therefore typically exceeds 30: 1 and is lower than 190: 1. These ratios provide up to 15 times higher torque-to-inertia ratios, up to 2.4 times higher torque-to-mass ratios, and at least 2 times lower power consumption.

[0124] The optimum overall transmission ratio of a proprioceptive actuator using the magnetorheological fluid clutch device 10 will then be higher than that of a quasi-direct drive, and therefore will typically exceed 10:1.

[0125] Fig.18 A typical single-motor single-clutch proprioceptive actuator is shown. These components are Figure 7 Similar to the components described in .

[0126] Fig.19 A table of more detailed actuator designs is shown to support and further illustrate the results of the preceding analysis. The quasi-direct drive actuators in the first and second columns are based on existing Maxon motors and have an overall reduction ratio of 8:1 between the motor and the end effector. The quasi-direct drive actuator in the third column is an interpolation of the first and second columns, based on a peak torque of 13Nm, and was chosen as a baseline comparison to a 13Nm magnetorheological fluid actuator topology because it represents the most widely used architecture in the state of the art proprioceptive robotics industry. This actuator can be found in a weight (610g) with a torque of 1411Nm / kgm 2 The invention provides a good compromise between the braking torque and inertia ratio. It is known to experts in the field that this quasi-direct drive configuration generates heat when the actuator needs to maintain a static force (for example, to hold a payload in a given position). Increasing the gearbox ratio will help reduce the heat generated, but will also be detrimental to the torque-to-inertia ratio. The performance of this type of quasi-direct drive body-sensing joint may be limited.

[0127] Fig.19 Column 4 shows Fig.12The magnetorheological fluid proprioceptive actuator with a structure has a peak braking torque of 13Nm. In this magnetorheological fluid proprioceptive actuator, the total reduction ratio is 32:1. As explained earlier, increasing the reduction ratio of the actuator will increase its torque density. Therefore, the magnetorheological fluid proprioceptive actuator can have a weight of 365g. In the case where the magnetorheological fluid clutch device 10 is not utilized in the motion chain (here represented as a magnetorheological fluid clutch device 10 in which the input rotor 14 is locked to the output rotor 11), the braking torque-to-inertia ratio of this actuator can be 546Nm / kgm 2 , and therefore lower than the quasi-direct drive configuration. When this actuator is locked, it will provide lower performance than the quasi-direct drive actuator of column 3 due to its higher reflected inertia. However, controlling the magnetorheological fluid clutch device 10 to disengage the input rotor 14 by slipping from the output rotor 11 can allow the inertia of the input rotor 14 to be reduced at the output, and therefore can allow the actuator to deliver 652083Nm / kgm 2 The brake torque to inertia ratio is over 400 times smaller than the prior art quasi-direct drive actuator of column 1. Because this actuator has a higher overall gear ratio than the quasi-direct drive (32:1 compared to 8:1), the power loss per Nm is only 9W / Nm compared to 15W / Nm of the quasi-direct drive of column 1, even when the power losses in the coils of the magneto-rheological fluid clutch device are taken into account. The magneto-rheological fluid body-sensing actuator is lighter, provides a better peak torque to inertia ratio, and has lower heat losses to keep the payload in place.

[0128] Note here that the 10:1 ratio can be the ratio of the rotary actuator gearbox or the ratio between the motor and the effective torque applied at the rotary joint by the linear actuator connected to the lever (e.g. Fig. 20 The ratio of 10:1 between motor and joint can also be obtained by a combination of belts, cables and winches, or any other combination of rotary-linear devices and then from linear-rotary devices. In this case, 6300N.m / kgm 2 The acceptable torque-inertia limit is not a value at the actuator itself, but rather an effective limit obtained at the joint. Therefore, rotation-translation mechanisms (e.g., lever arms, ball screws, racks and pinions, capstans, and cables, to name a few) and translation-rotation mechanisms (e.g., lever arms, ball screws, racks and pinions, capstans, and cables, to name a few) are considered part of the actuator mechanism.

[0129] Fig.21A linear magnetorheological fluid actuator 60 having a coil 65 is shown which can be used in various wheel suspensions for suspending a wheel assembly on a sprung body of a wheeled vehicle. The magnetorheological fluid actuator 140 allows the wheel assembly to move relative to the sprung body through a bounce and rebound vertical travel limited by a mechanical stop. The wheel assembly can be a rear wheel assembly or a front wheel assembly of a passenger vehicle (e.g., an automobile), a front wheel assembly or a rear wheel assembly of a motorcycle, or a front wheel assembly or a rear wheel assembly of a transport cart, to name a few examples. In some configurations, the relative center of rotation is disposed rearward and outboard of its respective pivot axis.

[0130] The active suspension system may include a magnetorheological fluid actuator 140 for each wheel assembly or only some of the wheel assemblies. In some configurations, a first structural link 141 may be coupled to the wheel assembly to define a first relative center of rotation and may be rotationally coupled to the sprung vehicle body at a first pivot, wherein the suspension further includes a second structural link 142 coupled to the wheel assembly to define a second relative center of rotation above the first relative center of rotation and rotationally coupled to the sprung vehicle body at a second pivot above the first pivot. The wheel suspension may define a geometry selected to minimize horizontal dynamic displacement of the wheel assembly as a structural link 143 attached between either the first structure 141 or the second structure 142 and the sprung vehicle body moves through an active control range over its vertical travel. In this case of a vehicle suspension having a complex mechanism (e.g., a four-bar linkage), 6300 N.m / kgm 2 The torque inertia limit of is also not a value of the actuator itself, but an effective limit obtained at the joint being actuated, in this case between the vehicle body and the first structural link 141. The wheels may be mounted to the structural link 143.

[0131] Proprioceptive actuators used in legged robots can be subject to high impact when the robot mimics human or animal motion (e.g., walking, running, or jumping). Since the contact time with the surface during locomotion can be of limited duration, any loss of control can hamper the robot's performance. Force or torque control between the limb and the surface becomes important.

[0132] In a quasi-direct drive actuator of the prior art, the actuator may need to operate in the typical four quadrants of the motor. The electronic system controlling this quasi-direct drive may then need to be able to power the motor and brake it while having a way to dissipate energy. Dissipating energy may present some challenges. It is known that four-quadrant electronics are more expensive to produce than two-quadrant systems. Therefore, it may be advantageous to use two-quadrant electronics and dissipate the impact energy directly in the magnetorheological fluid clutch device 10 by allowing some slip between the input rotor 14 and the output rotor 11. This can result in a lower cost electronic motor controller.

[0133] Another way to limit the cost of the electronics is to install the magnets within the magnetorheological fluid clutch device while removing the electromagnetic coil. By doing so, the magnetorheological fluid clutch device 10 can be used only to relieve the impact forces in the joint. The torque can be controlled by the motor source alone, but all of its reflected inertia will be filtered out or limited by the fluid slip properties of the magnetorheological fluid clutch device 10.

[0134] Thus, the magnetorheological fluid actuator in the embodiments described herein can be described as a proprioceptive magnetorheological (MR) actuator unit between bodies and can have: a bidirectional motor assembly; a reduction mechanism having a reduction ratio greater than 10:1; a magnetorheological fluid clutch device connected to the bidirectional motor assembly to transfer a variable amount of force from the bidirectional motor between at least two bodies using the reduction mechanism; at least one sensor for providing data indicative of a state of at least one body; a processing unit; and a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions that can be implemented by the processing unit to: receive data from at least one sensor, by which it is determined that the bidirectional motor assembly needs to be accelerated or decelerated to control the relative speed between the input and output of the magnetorheological fluid clutch device to transfer the required force between the bodies, control the bidirectional motor to accelerate or decelerate toward a given value, and simultaneously operate the magnetorheological fluid clutch device to transfer the required force between the bodies and maintain the braking torque-to-inertia ratio at a tactile limit, for example, for an actuator with a torque of 75 Nm, the tactile limit is in excess of 6300 N.m / kgm 2 , torque / (9E-6 torque 1.66667 )=6300N.m / kgm 2 (i.e. 9×10 -6 ×Torque 1.66667). A proprioceptive magnetorheological (MR) actuator unit may be used in a robot or in an active suspension for a vehicle, among other possibilities. The proprioceptive magnetorheological fluid actuator unit may be operated by a controller to reduce torque transfer from a magnetorheological fluid clutch device during a disturbance caused by impact or contact with the environment, during which the torque transfer does not correspond to a required force that can be achieved by control of the motor alone, the reduction occurring simultaneously with the acceleration or deceleration of the bidirectional motor toward a given value. It can be said that the bidirectional motor assembly operates within a first frequency range and the magnetorheological fluid clutch device operates within a second frequency range, the second frequency range being higher than the first frequency range. The proprioceptive magnetorheological fluid actuator unit may also or alternatively be operated by a controller to provide a required torque amplitude generated by the bidirectional motor, the controller keeping the bidirectional motor on even if the required torque amplitude is below a torque amplitude threshold to store mechanical momentum in a rotating component of the actuator unit, and then activating the magnetorheological fluid clutch device when the required torque amplitude is above the torque amplitude threshold to use the stored mechanical momentum. Thus, the magnetorheological fluid actuator unit described herein is able to achieve a certain level of braking torque to inertia ratio by limiting the inertia associated with the weight of the components, and in particular by having a single magnetorheological fluid clutch device to bi-directionally drive the magnetorheological fluid actuator unit by means of a single bi-directional motor. The presence of a speed reduction mechanism allows the torque ratio to be achieved while using a smaller motor, and the magnetorheological fluid clutch device compensates for the lack of bandwidth of the motor.

[0135] For electromechanical systems (motors, gearboxes), the torque-to-inertia ratio is not linearly proportional. Typical conversion laws estimate that the inertia is proportional to the 5 / 3 power of a function of the torque: I∝T^(5 / 3). Fig. 22 As shown, the tactile limit of a quasi-direct drive actuator with a torque of 75 Nm is estimated to be 6300 Nm / kgm 2 The tactile limit will decrease as the torque demand increases (e.g. 1120Nm / kgm 2 @1000Nm), conversely, it increases as the torque demand decreases (e.g. 24139Nm / kgm 2 @10Nm). This can also be Fig.19 As can be seen in the diagram, the Maxon EC90 quasi-direct drive has a lower torque-to-inertia ratio than the smaller version based on the EC60 motor. Fig. 22As shown, if the haptic limit is constant (e.g. application-dependent), this requires that the quasi-direct drive gearing needs to be adapted to achieve the haptic limit requirement. Assuming that the torque of the actuator increases in proportion to the transmission ratio, but the inertia of this actuator increases with the square of the transmission ratio, the torque-to-inertia ratio is roughly linearly proportional to the transmission ratio T / I∝Transmission. In order to keep the haptic limit constant, the gearing needs to decrease as the torque demand of the actuator increases (e.g. 1.8:1 at 1000Nm). Conversely, the gearing can increase as the torque demand decreases.

[0136] Fig.23 A schematic diagram of a proprioceptive linear electromagnetic actuator 230 using a magnetorheological fluid clutch device 10 is shown. In this embodiment, a motor stator (coil) 232 powers a rotor (magnet) 231, which can be connected to an input rotor 14 that defines a housing or casing of the magnetorheological fluid clutch device 10. The output member 11 of the magnetorheological fluid clutch device 10 can be connected to a screw 233. The screw 233 can be connected to a ball nut 234 (or ball screw, nut, etc.), which can be used to convert the rotary torque of the actuator into linear motion. Both ends 236 and 237 can be attached to a housing such as Fig. 20 The components shown.

[0137] The advantages described for proprioceptive robotic actuators can also bring similar benefits to other applications, such as active vehicle suspension and active seat suspension, to name a few, where maximizing the peak torque-to-inertia ratio may be desirable.

Claims

1. A proprioceptive magnetorheological (MR) fluid actuator unit, comprising: Bidirectional motor assembly; A reduction mechanism having a reduction ratio greater than 10:1; a magnetorheological fluid clutch device connected to the bidirectional motor assembly, the magnetorheological fluid clutch device being controllable to transfer a variable amount of force from the bidirectional motor between at least two bodies using the speed reduction mechanism; at least one sensor for providing data indicative of a status of at least one of said subjects; processing unit, and a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit to perform the following operations: receiving data from the at least one sensor, determining from the data that the bidirectional motor assembly should be accelerated or decelerated to a given value to control the relative speed between the input and output of the magnetorheological fluid clutch device, thereby transmitting a desired force between the two bodies, controlling the bidirectional motor to accelerate or decelerate toward the given value, and The magnetorheological fluid clutch devices are simultaneously operated to transfer the desired force between the bodies while maintaining a brake torque to inertia ratio above a tactile limit.

2. The proprioceptive magnetorheological fluid actuator unit according to claim 1, wherein: The first body is a mass body, and the second body is a structure body.

3. The proprioceptive magnetorheological fluid actuator unit according to claim 2, wherein: The mass body is connected to the structure body through a spring.

4. The proprioceptive magnetorheological fluid actuator unit according to claim 3, wherein: The mass body is controlled to achieve active suspension.

5. The proprioceptive magnetorheological fluid actuator unit according to claim 1, wherein: The bodies are links of the robot interconnected by joints.

6. The proprioceptive magnetorheological fluid actuator unit according to claim 5, wherein: The robot is a robot having a limb, and the link is a part of the limb.

7. The proprioceptive magnetorheological fluid actuator unit according to any one of claims 1 to 6, wherein: At least two of the bodies are interconnected by a rotating joint.

8. The proprioceptive magnetorheological fluid actuator unit according to any one of claims 1 to 7, wherein: The speed reduction mechanism includes a rotational to linear converter for the proprioceptive magnetorheological fluid actuator unit to transfer translational force between the bodies.

9. The proprioceptive magnetorheological fluid actuator unit according to any one of claims 1 to 7, wherein: The speed reduction mechanism includes a rotation-to-rotation arrangement for the body-sensing magnetorheological fluid actuator unit to transfer torque between the bodies.

10. The proprioceptive magnetorheological fluid actuator unit according to any one of claims 1 to 9, wherein: The computer readable program instructions are executable by the processing unit to cause the magnetorheological fluid clutch device to slip when the brake torque to inertia ratio exceeds the tactile limit.

11. The proprioceptive magnetorheological fluid actuator unit according to any one of claims 1 to 10, wherein: For the proprioceptive magnetorheological fluid actuator unit, when the torque is in Nm, the tactile limit is in Nm / kgm 2 When the unit is equal to torque / (9×10 -6 ×Torque 1.66667 ).

12. The proprioceptive magnetorheological fluid actuator unit according to any one of claims 1 to 11, wherein: For the actuator unit, when the torque is 75Nm, the tactile limit is 6300N.m / kgm 2 .

13. The proprioceptive magnetorheological fluid actuator unit according to any one of claims 1 to 12, wherein: The magnetorheological fluid clutch device has at least 1×10 6 Nm / kg.m 2 Torque to inertia ratio.

14. The proprioceptive magnetorheological fluid actuator unit according to any one of claims 1 to 13, wherein: The reduction mechanism has a contact ratio of at least 2 between the torque transmitting elements.

15. The proprioceptive magnetorheological fluid actuator unit according to claim 14, wherein: The speed reduction mechanism includes a plurality of load paths.

16. The proprioceptive magnetorheological fluid actuator unit according to claim 15, wherein: The speed reduction mechanism is a planetary gear mechanism having at least two planetary gears.

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