Systems and methods for controlling commutation events using magnetorheological fluids

Abstract

A system for operating a magnetorheological (MR) fluid actuator unit between bodies may have at least one MR fluid actuator unit including a motor assembly operating within a first frequency range and an MR fluid clutch device operating within a second frequency range. The MR fluid clutch device is connected to the motor assembly to apply a variable amount of force from the motor assembly between the at least two bodies, the MR fluid clutch device operating within a second frequency range, the second frequency range being higher than the first frequency range. The at least one sensor provides data indicative of a status of at least one of the bodies. The system may be used to: receive data from at least one sensor; determining a magnitude and direction in which the motor assembly must be accelerated or decelerated to control a relative speed between an input and an output of the MR fluid clutch device from the data to transfer a desired force between the bodies; the motor assembly is controlled to accelerate or decelerate toward a given value at a first frequency range and simultaneously reduce a torque transfer from the MR fluid clutch apparatus during a hysteresis period in which the torque transfer acts counter to a desired force.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application No. 63 / 341,501, filed on May 13, 2022, the contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates generally to magnetorheological (MR) fluid clutch devices and, more particularly, to subjects using such devices for dynamic control of motion in active motion control, suspension systems, collaborative robotics, or haptic systems. Background Art

[0004] A subject (such as a vehicle) moving in a desired direction will most inevitably experience movement in other directions as well. Such undesirable movement is usually caused by disturbances in the medium through which the subject travels. For example, in a vehicle, whether traveling by land, sea or air, one may encounter bumps, jolts, waves, air pockets, etc. Such random accelerations may cause displacement, discomfort or annoyance of the personnel in the vehicle. This may also cause vibration and undesirable horizontal or vertical movement of the cargo in the subject. For some susceptible individuals, these random accelerations may trigger an attack of motion sickness. In some cases, particularly severe accelerations may cause the operator to temporarily lose control of the body. In addition, cargo may be damaged when subjected to acceleration or impact. Even when stationary, there may be some residual vibrations associated with the engine of the vehicle. In motion, even on a flat road, this residual vibration may become annoying.

[0005] The primary purpose of a body's suspension system is to provide vertical or horizontal compliance between a medium (such as a road) and the chassis in order to isolate the chassis occupants or cargo from the roughness in the road and to maintain a contact point with the road, thereby providing a path for transferring forces from the contact point to the chassis. In applications where the body is a body with wheels, the contact point is also used to change the speed or direction of the body. In bodies with wheels, some common examples of independent suspension linkages are generally referred to as strut links (also known as MacPherson struts), double A-arms (also known as double wishbones or SLAs), trailing arms, semi-trailing arms, multi-links, wishbones, scissor arms, pivots, to name a few.

[0006] In a vehicle (such as a car), each wheel assembly is connected to the chassis via one or more links. A link is defined as a substantially rigid member with one or more joints at each end that allow a specific movement to occur. It is these links that control the movement (or path) of the wheel as it moves up and down over bumps in the road.

[0007] The design of a suspension system for damping wheel oscillations usually represents a trade-off between, on the one hand, isolating the vehicle body from high-frequency oscillations (secondary suspension oscillations) that may be generated by road surface irregularities, and, on the other hand, achieving a high level of driving comfort with respect to low-frequency oscillations of the vehicle body (primary suspension oscillations).

[0008] In general, all kinematically induced wheel forces are either forces resulting from the interaction between the tire and the road or inertial forces resulting from the motion of the unsprung mass. The forces arising between the tire and the road are transmitted to the body via the suspension system. As long as the wheel assembly does not change its horizontal position or angular orientation relative to a flat road surface, no significant lateral or longitudinal tire forces are generated (neglecting friction).

[0009] In an active suspension, a controlled force is introduced into the suspension between the suspended mass of the vehicle body and its occupants and the unsprung mass of the wheel assembly, such as by a hydraulic or electric actuator. The unsprung mass is an equivalent mass that reproduces the inertial forces generated by the motion of those parts of the vehicle that are not carried by the suspension system. This primarily includes the wheel assembly, any mass dampers associated with the wheel assembly, and a certain portion of the mass of the suspension linkage. The suspended mass is the mass of those parts of the vehicle (including the body) that are carried by the suspension system. Active suspension systems can introduce forces that are independent of relative wheel motion and speed.

[0010] Known active suspension systems use a linear motor direct drive approach. This approach may be considered adequate from a performance point of view. However, this approach can be said to be fragile, heavy and costly. Another known suspension system is an electro-hydraulic active system based on a pump that adjusts the pressure of the hydraulic fluid in a conventional hydraulic damper. The electro-hydraulic approach is generally not dynamic enough (not sufficiently bandwidth) to cope with a full range of road-induced disturbances. This approach is generally able to cope with the primary suspension attitude changes (such as pitch and roll) of the vehicle, but may worsen the secondary suspension because it adds some inertia or reflected inertia on the non-suspension mass side. In other words, an improvement in the primary suspension is achieved, but some active suspension systems do not reduce the vibrations associated with the frequency of the secondary suspension, but rather exacerbate the vibrations, making them less attractive. To address this issue, springs have been introduced in series with some suspension actuators and the non-suspension mass to achieve a series elastic suspension system. However, this added spring may generally be accompanied by a reduction in the natural frequency of the system, thereby reducing the mechanical bandwidth and reducing controllability.

[0011] Actuators using magnetorheological (MR) fluid clutch devices have been proposed to solve most of the aforementioned problems, because active suspension systems with such MR fluid actuators can exhibit high bandwidth and high transparency. However, active suspension systems may be considered more complex and costly, such as in a configuration with two MR fluid clutch devices per unsprung mass.

[0012] For this reason, there remains a need for a more economical active suspension system.

[0013] Although the above description relates to vehicles, similar situations can be found in other types of devices, equipment, and systems, such as tactile feedback devices that are used to transmit force feedback to humans or robots that interact with humans or unpredictable environments. Summary of the invention

[0014] An object of the present disclosure is to provide a novel active motion control system using a magnetorheological fluid clutch device.

[0015] It is another object of the present disclosure to provide a method and system for minimizing controllability loss during commutation when the dynamics produced by the combination of the motor and reduction mechanism of the MR fluid actuator are slower than the motion system requires.

[0016] Another object of the present disclosure is to provide a novel active suspension control system using a magnetorheological fluid clutch device.

[0017] Yet another object of the present disclosure is to use such a system in a vehicle.

[0018] According to a first aspect of the present disclosure, there is provided a system for operating a magnetorheological (MR) fluid actuator unit between bodies, comprising: at least one MR fluid actuator unit including a motor assembly and a MR fluid clutch device, the motor assembly operating within a first frequency range, the MR fluid clutch device connected to the motor assembly to apply a variable amount of force from the motor assembly between at least two of the bodies, the MR 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 of the bodies; a processing unit; and a non-transitory computer readable memory communicatively coupled to the processing unit and including computer readable program instructions executable by the processing unit for: receiving data from the at least one sensor; determining from the data an amplitude and a direction at which the motor assembly must be accelerated or decelerated to control a relative velocity between an input and an output of the MR fluid clutch device to transfer a desired force between the bodies; and controlling the motor assembly to accelerate or decelerate toward a given value within the first frequency range and simultaneously reducing torque transfer from the MR fluid clutch device during a hysteresis period in which the torque transfer acts opposite to the desired force.

[0019] According to further the first aspect, for example, a motor assembly includes a motor and a speed reduction mechanism.

[0020] According further to the first aspect, for example, reducing torque transmission includes closing the MR fluid clutch device.

[0021] According further to the first aspect, for example, reducing torque transmission includes delaying a response of the MR fluid clutch device during a hysteresis period.

[0022] According further to the first aspect, for example, reducing torque transfer includes delaying a response of the MR fluid clutch device during a hysteresis period while the system remains within a predefined operating zone.

[0023] According further to the first aspect, for example, the motor assembly includes at least one unidirectional motor.

[0024] According further to the first aspect, for example, the motor assembly includes at least one bidirectional motor.

[0025] Further according to the first aspect, for example, determining from the data that the motor assembly must be accelerated or decelerated to control the magnitude includes controlling a direction of relative velocity between an input and an output of the MR fluid clutch device to transmit a desired force between the bodies.

[0026] According further to the first aspect, for example, there may be two MR fluid actuator units, each having a bidirectional motor connected to a respective one of the MR fluid clutch devices, the two MR fluid actuator units controlling a desired force on a common output.

[0027] According further to the first aspect, for example, a first one of the bodies is a mass, and a second one of the bodies is a structure.

[0028] According further to the first aspect, for example, the structure is suspended from the mass.

[0029] According further to the first aspect, for example, the system is an active suspension that generates energy in the passive quadrant.

[0030] According further to the first aspect, for example, the system is an active suspension using energy in the active quadrant.

[0031] According further to the first aspect, for example, the main body is a link of a robot.

[0032] According further to the first aspect, for example, the robot is a collaborative robot.

[0033] According further to the first aspect, for example, the main body is a fixed chassis and a haptic device.

[0034] According further to the first aspect, for example, the hysteresis period corresponds to a duration during which an absolute slip velocity of the MR fluid clutch device is less than a desired slip threshold.

[0035] Further in accordance with the first aspect, for example, the system can be configured to: determine a desired speed magnitude to be produced by the bi-directional motor based on the data; maintain slip in the MR fluid clutch device to maintain in a current direction and not respond to a desired slip speed magnitude reversal if the desired absolute torque magnitude is within a torque magnitude threshold, and reversing the slip speed of the MR fluid clutch device if the desired absolute torque magnitude exceeds the torque magnitude threshold in an opposite direction.

[0036] According to a second aspect of the present disclosure, a system for operating a suspension between a mass and a structure is provided, comprising: a bidirectional motor; a magnetorheological (MR) fluid clutch device coupling the bidirectional motor to the mass to apply a force from the bidirectional motor to the mass; at least one sensor for providing data indicative of a state of the mass and / or the structure; a 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 for: receiving data from the at least one sensor; determining a desired velocity magnitude to be generated by the bidirectional motor based on the data; maintaining slip in the MR fluid clutch device to maintain in a current direction and not responding to a desired slip velocity magnitude reversal if the desired absolute torque magnitude is within a torque magnitude threshold, and reversing the slip velocity of the MR fluid clutch device if the desired absolute torque magnitude exceeds the torque magnitude threshold in an opposite direction.

[0037] According to a third aspect of the present disclosure, there is provided a system for operating a suspension between a mass and a structure, comprising: a bidirectional motor operating within a first frequency range; a magnetorheological (MR) fluid clutch device coupling the bidirectional motor to the mass to apply a force from the bidirectional motor to the mass, the MR 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 the mass and / or structure; a 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 for: receiving data from the at least one sensor; determining a switching direction of the bidirectional motor based on the data; and simultaneously controlling the bidirectional motor to reduce torque transfer from the MR fluid clutch device when slip is not in a desired direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic diagram of a generalized magnetorheological (MR) fluid clutch device incorporating features of the present disclosure.

[0039] Figure 2 According to the implementation method Figure 1 Schematic cross-section of an MR fluid clutch device.

[0040] Figure 3 is a schematic illustration of an MR fluid actuator using a single motor and a single clutch.

[0041] Figure 4 is a schematic illustration of an MR fluid actuator using a single motor and dual clutches.

[0042] Figure 5 is a schematic illustration of two MR fluid actuators organized in a parallel path.

[0043] Figure 6 is a schematic illustration of an MR fluid actuator for controlling a vehicle seat.

[0044] Figure 7 is a schematic illustration of an MR fluid actuator used to control a truck cab.

[0045] Figure 8 is a schematic illustration of an MR fluid actuator for controlling a frame of a vehicle.

[0046] Fig. 9 is a graph showing forces and velocities for a typical vehicle active suspension.

[0047] Fig.10 is a typical Bode plot of an MR fluid actuator.

[0048] Fig.11 is a typical PSD plot of an active suspension using MR fluid actuation compared to a passive suspension.

[0049] Fig.12 is a schematic illustration of an exemplary comfort improvement of an active suspension using MR fluid actuators compared to the prior art.

[0050] Fig.13 A diagram that characterizes the mechanical vibration and shock evaluation of human body exposure to whole body vibration using the ISO 2631 filter.

[0051] Fig.14 is a schematic illustration of a vehicle suspension using a linear MR fluid actuator.

[0052] Fig.15 is a perspective view of an exemplary embodiment of a linear MR fluid actuator.

[0053] Fig.16a yes Fig.15 A more detailed illustration of a linear MR fluid actuator.

[0054] Fig.16b yes Fig.15 An alternative configuration of a linear MR fluid actuator with a single motor.

[0055] Fig.17 is a schematic illustration of a vehicle suspension using a rotary MR fluid actuator.

[0056] Fig.18a is a schematic illustration of a possible rotary MR fluid actuator.

[0057] Fig.18b is an alternative configuration of the linear actuator of FIG. 18 having a single motor.

[0058] Fig.19 yes Fig.15 A more detailed illustration of a rotary MR fluid actuator.

[0059] Fig. 20 is a schematic illustration of an exemplary linear MR fluid actuator using a rack and pinion coupled with a single motor and a single clutch.

[0060] Fig.21 are a pair of graphs illustrating the conditions for commutation in an MR motion control system.

[0061] Fig. 22 is a series of graphs illustrating the limitations of a single motor single clutch active suspension compared to a dual clutch active suspension design.

[0062] Fig.23 are a pair of graphs of exemplary motor consumption for a single motor single clutch active seat suspension compared to a single motor dual clutch suspension.

[0063] Fig.24 is a table of exemplary results of a single motor single clutch active seat suspension compared to a single motor dual clutch suspension on different types of roads.

[0064] Fig.25 It shows Fig. 20 A pair of diagrams of the hold-slip function of a single motor single clutch system.

[0065] Fig.26 It shows Fig. 20 A series of diagrams of the hands-off function of a single motor single clutch system.

[0066] Fig.27a is a graph showing linear and nonlinear plots of the torque amplifier as a function of the slip target.

[0067] Figure 27b is a graph showing linear and nonlinear plots of the torque amplifier as a function of the slip target at zero command.

[0068] Fig.28 is a block diagram of a controller for any of the MR fluid actuators described herein. DETAILED DESCRIPTION

[0069] With reference to the drawings and more particularly with reference to Figure 1, a magnetorheological (MR) fluid clutch device 10 is shown that is configured to provide a mechanical output force based on a received input current. The MR 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 MR fluid clutch devices, such as some configurations having an input or output housing / housing for the output or input shaft, etc. The principles described herein will be performed using a drum-type MR fluid clutch device, but can also be applied to a disc-type MR fluid clutch device. In the following description, from Figure 3 Initially, reference is made to systems and MR fluid actuators having one or more MR fluid clutch devices 10. When such reference is made, unless otherwise specified, the MR fluid clutch device 10 may be as described herein. Figure 1 and Figure 2 , or may be any other MR fluid clutch device 10, such as a version with a disc. In some embodiments, the MR fluid clutch device 10 may be a normally open, normally closed, or partially closed clutch type unit.

[0070] The MR fluid clutch device 10 can transmit 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 example MR fluid clutch device 10 can have a stator 10A, through which the MR fluid clutch device 10 is connected to a certain structure. The MR fluid clutch device 10 features a driven member 11 and a driving member 12, which are separated by a gap filled with MR fluid, as explained below. The driving member 12 can receive rotational energy (torque) from a power device (such as a motor) with or without a transmission device (such as a reduction gearbox, etc.).

[0071] According to an embodiment, the driving member 12 can be in mechanical communication with a power input, and the driven member 11 can be in mechanical communication with a power output (i.e., a force output, a 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 preserve the MR fluid between the members 11 and 12. In addition, the seal is configured to prevent the MR fluid from reaching the bearing 12B or leaking from the device 10.

[0072] As reference Figure 2 As shown, the drum is positioned circumferentially around the axis of rotation CL. Therefore, some of the supports must extend substantially radially to support the drum in its circumferential arrangement. According to one embodiment, with reference to Figure 2 , a low 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, which defines an outer housing or shell of the MR fluid clutch device 10. The input rotor 14 can therefore be rotatably connected to the driven member 11 via a bearing 12B. In an embodiment, the input rotor 14 has an input rotor support 14A, which forms a housing for the bearing 12B. According to an embodiment, the input rotor support 14A is an integral part of the input rotor 14 and can be manufactured as a single piece. However, this is not desirable because the input rotor support 14A is ideally made of a low permeability material and the input rotor is made of a high permeability material. As another embodiment, Figure 2 As 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 for common rotation. Thus, the shaft of the drive member 12, the input drum support 13, and the input rotor 14 rotate together. In an embodiment, it is contemplated that the housing of the MR fluid clutch device 10 is made part of the stator 10A or the driven member 11.

[0073] The input drum support 13 may support a plurality of concentric annular drums 15, also referred to as input annular drums. The input annular drums 15 are secured to the input drum support 13. In an 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., a press fit), an adhesive, and / or radial pins may be used to secure the drums 15 to the input drum support 13. In an 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 together upon receiving drive from a power source.

[0074] The driven member 11 is represented by an output shaft, also configured to rotate about the axis CL. The output shaft can be coupled to various mechanical components that receive the transmitted power output when the clutch device 10 is actuated to transmit at least some rotational power input. In some embodiments, some other components of the MR fluid clutch device 10 can be attached or combined with other components (i.e., the drive member 12 can be combined with the stator 10a, the drum support 13, the input rotor 14, and the rotor support 14A, so all of these parts can be anchored to the chassis and do not rotate).

[0075] The driven member 11 also has one or more concentric annular drums 16, also called output drums, which are mounted to an output drum support 17. The output drum support 17 can be an integral part of the output shaft, or can be mounted on the output shaft for common rotation. The annular drums 16 are spaced apart in such a way that each set of output annular drums 16 fits in an annular space between the input annular drums 15 in a staggered manner. When either the driven member 11 or 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.

[0076] The annular space between the input annular drum 15 of the driving member 12 and the output annular drum 16 of the driven member 11 is filled with an MR fluid 19. The MR fluid 19 used to transmit force between the driven member 11 and the driving member 12 is a smart fluid consisting of magnetizable particles arranged in a carrier fluid, which is usually an oil, but the carrier fluid can also exist in gaseous form (also known as dry MR fluid). 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 between the operating shear stress and the operating shear rate of the MR fluid between the opposing shear surfaces. The magnetic field strength mainly affects the yield shear stress of the MR fluid.

[0077] according to Figure 3 , shows an MR fluid actuator 20 (also referred to as an MR fluid actuator unit) having an MR fluid clutch device 10 of the above-described type. The actuator is composed of a motor 21, an input gearbox 22, the MR fluid clutch device 10, an output gearbox 23, and an output 24, but one or both of the gearboxes may be optional.

[0078] Another type of MR fluid actuator is Figure 4 , and consists of a single motor, an input gearbox 22 , two MR fluid clutch devices 10A and 10B which rotate in opposite directions and exert opposing forces on an output 24 via gearboxes 23A and 23B, respectively.

[0079] Another type of MR fluid actuator is Figure 5 is shown in and is represented by Figure 3 Two similar MR fluid actuators are constructed, which work in parallel to apply force on a single output 24, where the gearbox is optional. The first actuation branch is composed of a motor 21A, an input gearbox 22A, an MR fluid clutch device 10A, and an output gearbox 23A that drives the output 24. The first and second actuation branches are composed of a motor 21B, an input gearbox 22B, an MR fluid clutch device 10B, and an output gearbox 23B that drives the output 24.

[0080] Figure 6 , Figure 7 and Figure 8 The active suspension system 60 is integrated into the Figure 3 , Figure 4 or Figure 5 The suspension 60 is referred to as "active" because it applies forces to different types of masses (such as platforms) relative to the structure of the vehicle through the controlled MR fluid actuators 20. More specifically, Figure 6 An active suspension 60 for controlling a seat of a vehicle is shown, Figure 7 An active suspension 60 is shown controlling the cab of the truck, and Figure 8 An active suspension 60 is shown mounted to control the frame of a vehicle. Each active suspension 60 can control the force between a suspended platform or similar mass and a base or similar structure below. The force can be independent of relative motion and velocity in the environment of or at the suspended platform. The active suspension system 60 has or receives actuation from at least a power source 21, such as a motor. The motor 21 can be electric, pneumatic, hydraulic, ICE, or any other type. The active suspension system 60 has a mechanism in the form of a linkage system that is coupled to a platform 61 (e.g., a seat, a tray, a stretcher, a truck cab, a shipping box, to name a few) to transmit motion output by the MR fluid clutch device 10 to the platform 61. One or more sensors 62 provide information indicative of the state of the suspended platform 63, and a controller 64 receives the information indicative of the state of the platform 63 and outputs a signal to the MR fluid clutch device 10 to cause the MR fluid clutch device 10 to apply a force on the suspended platform 63. Alternatively, the sensors 62 may be located on the structure supporting the platform 63, and / or on components of the active suspension system 60 to measure the state of any such components. Additional components may be provided in parallel with the linkage, such as an air spring 65 or similar biasing device or suspension component. Other actuators or damping devices 66 may also be added in parallel or in series with the MR fluid actuator 20. The damping device may be of an adjustable type or a non-adjustable type. It should be noted that for simplicity, the explanation is described in terms of control of one degree of freedom, but multiple actuators may also be used to control multiple degrees of freedom of the body. In addition, multiple MR fluid clutch devices may share the same power source, such as Figure 3 , where two MR fluid clutch devices 10 receive actuation power from a single motor 21 via a transmission 22. The transmission 22 is shown as featuring a gearbox, but pulleys and belts may also be used. The transmission 22 may also be of other types, such as chains and pinions, to name a few. As an alternative to the air spring 65, other devices may be used as a variable force source.

[0081] The combination of a variable power source and the MR fluid clutch device 10 presents the advantages of a hybrid system where one device or the other (or both) can be controlled depending on the operating conditions. In the example where the power source is an electric motor, the electric motor speed and available torque can be controlled as well as the torque delivered by the MR fluid clutch device 10. This can increase the potential operating points while improving the overall performance or efficiency of the system. The output of the MR fluid clutch device can be decoupled from the input. In some applications, this is useful to decouple inertia from the input so as not to affect the response time of the output.

[0082] Figures 6 to 8 63, and / or components of the active suspension system 60, and the controller 64 outputs a signal to the MR fluid actuator 20 based on the state. For example, the controller 64 may be programmed with a desired behavior of the platform 63. The desired behavior may be a comfort behavior, in which the platform 63 is not subjected to accelerations exceeding a given level in a particular direction (e.g., up and down). Thus, the controller 64 will control the actions of the MR fluid actuator 20 to ensure that the platform 63 moves within the limits of the desired behavior, regardless of the disturbances to which the structure (e.g., the vehicle chassis) is subjected. Likewise, the desired behavior may be a control behavior, meaning that the platform 63 limits its span of movement in some controllable direction. Thus, the active suspension system 60, as well as other embodiments of the suspension described below, employ active control, in which forces are applied to control the movement behavior of an item (such as a passenger support platform or a wheel assembly, to name a few).

[0083] Fig. 9 An exemplary force versus velocity (FV) diagram of a typical active suspension for a vehicle is shown. The FV is shown for each of the four wheels.

[0084] Fig.10 An exemplary mechanical transfer function of an MR fluid actuator 20 is shown when the MR fluid clutch device 10 is held slipping. Such transfer functions are shown when used with and without a feedforward controller. It is known that MR fluid actuators such as 20 provide high mechanical bandwidth (e.g., >10 Hz) when one or more MR fluid clutch devices are held slipping.

[0085] Fig.11 is an exemplary power spectral density (PSD) plot showing typical frequencies experienced by a vehicle suspension system. There may be significant power up to about 50 Hz, so it may be advantageous for an active suspension system to provide reaction forces up to this frequency.

[0086] Fig.12The discomfort index J for various passive suspensions, semi-active suspensions, slow active suspensions, and full active suspensions is shown. The lower the discomfort index J, the more comfortable the suspension platform is likely to be.

[0087] Fig.13 The use of ISO 2631 filters to characterize the mechanical vibration and shock assessment of a human subject to whole body vibration is shown. It can be seen that the most important frequencies for improving human comfort are between 1 Hz and 30 Hz, where the gain on the filter is greater than 0.5.

[0088] Fig.14 A linear MR fluid actuator is shown that can be used in various wheel suspensions for suspending a wheel assembly on a suspension body of a vehicle with wheels. The MR fluid actuator 20 allows the wheel assembly to move relative to the suspension body through a bounce and rebound vertical travel such as limited by mechanical stops. The wheel assembly can be a rear wheel assembly and / or a front wheel assembly of a passenger vehicle (such as an automobile), a front or rear wheel assembly of a motorcycle, a front or rear wheel assembly of a transportation vehicle, to name a few. In some configurations, the relative rotation center is disposed rearward and outboard of its respective pivot.

[0089] In some cases, the upper relative rotation center and the upper pivot are arranged along a first generally horizontal line, and the lower relative rotation center and the lower pivot are arranged along a second generally horizontal line, wherein the vehicle is at rest and loaded to its design weight. The upper and lower rotation centers are preferably separated from their respective pivots by different arm lengths. The term "design weight" should be understood from ISO / IS2958, which specifies the functional relationship between the load of a passenger vehicle and the number of seats. Typically, the suspension is approximately at the center of its vertical travel when at rest at the design weight. In some embodiments, the active suspension system includes an electric motor adapted to receive electrical power, which is coupled to one or more of the MR fluid actuators of the active suspension system 60 to generate active control forces.

[0090] The active suspension system may include a subsystem 140 for each wheel assembly. In some configurations, a first structural link 141 may be coupled to the wheel assembly to define a first relative rotation center and may be rotationally coupled to a suspension 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 rotation center above the first relative rotation center and rotationally coupled to the suspension body at a second pivot above the first pivot. When a structural link 143 attached between either the first or second structure and the suspension body moves through an active control range over its vertical travel, the wheel suspension may define a geometry selected to minimize horizontal dynamic displacement of the wheel assembly.

[0091] Reference Fig.15, the subsystem uses a pair of MR fluid clutch devices 10, 10' to control the rotation of a threaded rod 151 featuring a ball screw or similar actuator with a threaded nut 152 using power provided by motors 21, 21' (although a single motor may also be used as previously illustrated). The rotational output from the motors 21, 21' is thus converted into a fore-and-aft translation of the threaded rod 151. Fig.15 The subsystem can be placed in the middle of the coil spring (such as Fig.15 as shown) or placed in parallel with the strut or spring / damper system.

[0092] The rotational output from motors 21 and 21' is transmitted to the input of MR fluid clutch devices 10 and 10' using mechanisms 84 and 84'. The input reduction mechanism 84 can rotate in a clockwise direction, while the input reduction mechanism 84' can rotate in a counterclockwise direction. The belt system can present the advantage of having less backlash than some other types of reduction mechanisms. Other types of backlash reduction strategies may also be desirable, such as preloaded gears or preloaded ball screws, to name a few. Therefore, the rotation caused by either MR fluid clutch device 10 or 10' is converted into a forward and backward translation of the nut 152 connected to the sliding member 88 through the engagement of the ball screw lever 151 and the nut 152. The subsystem can be placed in the middle of the hollow center volume of the coil spring 65, or placed in parallel with the strut or spring / damper system.

[0093] Fig.16a Shows Fig.15 A cross section of a device showing that the output members of the two MR fluid clutch devices 10 and 10' can be connected to a single output, which in this case is a threaded ball screw lever 151 of a ball screw mechanism or other rod for other types of linear actuators. In the embodiment shown, the output is connected to the screw, but other embodiments are possible in which the outputs of the MR fluid clutch devices 10 and 10' can be connected to a common ball nut, or each connected to a separate ball nut. Connecting each clutch to a separate ball nut can present the advantage of reducing the backlash of the system when the two clutches work antagonistically.

[0094] Fig.16b Shown with Fig.16a 2, having an alternative configuration in which only one MR fluid clutch device 10 is connected to the motor 21. The MR fluid clutch device 10' is connected to the chassis of the device. The output members of both MR fluid clutch devices 10 and 10' are connected to a single output, which is a threaded ball screw lever 151 of a ball screw mechanism.

[0095] exist Fig.17In the illustrated embodiment, the motor and MR fluid clutch device 10 may be located remotely from the wheel assembly, with various configurations for transmitting motor actuation to the wheel assembly being illustrated. Fig.17 A rotary mechanism is shown which is configured to receive force from a MR fluid clutch device 10 as part of an active suspension system 60 to actively control a wheel assembly or other portion of a vehicle. Distal actuation may be transmitted using a push rod, but hydraulic tubes or cables may also be used to form part of the mechanism.

[0096] refer to Fig.18a and Fig.19 , showing the Fig.15 A configuration similar to that of , but using output reduction transmissions 86 (eg, bevel gears) and 86 ′ instead of ball screws, the output reduction mechanisms 86 and 86 ′ each having an output shaft 87 and 87 ′ connected to a single actuator output member 88.

[0097] Fig.18a Embodiments of or other embodiments described herein may also be used as part of a robot joint. Such a system is described in International Patent Application Publication No. WO 2021155478A1, which is incorporated herein by reference.

[0098] Fig.18b Shown with Fig.18a A cross section of a device similar to that of FIG. 1 has an alternative configuration in which only one MR fluid clutch device 10 is connected to the motor 21. The MR fluid clutch device 10' is connected to the chassis of the device. The output members of both MR fluid MR fluid clutch devices 10 and 10' are connected to a single output.

[0099] According to another embodiment (not shown), the active suspension system can be applied to a rollover bar of a motor vehicle. The rollover bar can be located on the rear wheels of the vehicle, but it is also possible to use another rollover bar on the front wheels. The rollover bar can be a split torsion bar, which is rotatably fastened to the vehicle chassis. It is also considered that a clutch arrangement connects a first rollover bar part to a second rollover bar part so that they rotate in unison depending on the actual and / or expected lateral acceleration of the vehicle. Thus, the rollover bar can be automatically disengaged during straight-line travel of the vehicle and automatically coupled again during curved travel.

[0100] According to an alternative embodiment, a clutch arrangement of the rollover bar can be implemented if the first rollover bar portion and the second rollover bar portion can be connected to each other to rotate in unison so that they can be axially displaced as a whole by a clutch arrangement. The clutch arrangement can be preferably controlled according to the speed of the vehicle, and the steering angle and / or angular velocity of the steered wheels, and / or the lateral acceleration of the vehicle (all of which can be part of the state of the vehicle obtained by the sensor 62). In order to eliminate safety hazards during possible failures, the clutch arrangement can have redundancy so that at least partial functionality is still maintained in the event of a defect. In another embodiment, the active suspension system with the MR fluid clutch device 10 can be installed in parallel or concentrically with a soft torsion bar and only used as a stiffness increaser. Therefore, the active suspension system as described above is a relatively cost-effective semi-active or fully active rollover bar, which is always effective enough during curve travel and in avoidance maneuvers, and also affects the spring action characteristics of the vehicle to improve ride smoothness.

[0101] In another embodiment (not shown), the MR fluid actuator (such as 20) is located distally, and the spring 65 and hydraulic actuator or piston are located at each wheel in a parallel arrangement. The MR fluid clutch device 10 uses two distinct hydraulic conduits to provide active motion control to each wheel in two directions. One of the hydraulic conduits can be used to transmit the required active motion control force to the hydraulic actuator or piston at the wheel in one direction, while the other conduit can be used to transmit force in the other direction. The biasing member or spring 65 can be used to support the suspended weight and transfer part of the load to the non-sprung weight.

[0102] Fig. 20 A system is shown with a single motor 21 and a single MR fluid clutch device 10. A single MR fluid clutch device 10 is used in conjunction with a pinion 203 on a structural link 201, which provides braking of movement of the structural link 201 in the unbiased direction by exerting a force on a rack portion 204, thereby acting as an MR fluid brake. In an embodiment, the motor 21 may be a bi-directional motor.

[0103] Fig.211 is a diagram showing the conditions of a reversing event (also known as a change or switch in direction of the output of the system) in an MR fluid motion control system (e.g., from CW to CCW or vice versa, from X translation to -X translation or vice versa). For example, an arrangement includes a motor 21, an optional input reduction mechanism 84, and an MR fluid clutch device 10, wherein the input member 12 spins at a different speed than the output member 11 to provide a slip condition that decouples the input inertia from the output. The slip direction within the MR fluid clutch device 10 controls the direction (positive or negative) of the output torque transmitted. When the MR fluid clutch device 10 slips to change direction, undesirable slip direction reversals may occur, such as: A) when the input member 12 initially spins faster than the output member 11 and transitions to a state where it spins slower than the output member 11, switching from a positive torque to a negative torque; B) when the input member 12 initially spins slower than the output member 11 and transitions to a state where it spins faster than the output member 11, switching from a negative torque to a positive torque.

[0104] Real-time switching of the slip direction can allow the controller to maximize torque output and controllability. In an arrangement featuring two motors 21 and two MR fluid clutch devices (such as in Fig.18a and Fig.19 In the case of (in) this may mean that only one MR fluid actuator unit 20 (i.e. one motor 21 and one branch of the MR fluid clutch device 10) is switching to switch from cooperative slipping (where the two branches of the arrangement can add torque to the output) to an opposing slipping mode (where the two branches apply torque on the output in opposite directions). This is explained in patent application number WO 2021155478A1, which is incorporated herein by reference. This real-time transition mode of the MR fluid actuator requires one of the clutch input speed members 12 or 12' (ω c,1 or c,2 ) increases or decreases so that relative to the output speed ω a Switch side (see Fig.18a ). In this example, the two output members 11 and 11' can rotate at the same speed, because if the two output reduction mechanisms 86 and 86' have the same mechanical transmission ratio. However, different ratios are possible, and therefore ω a and ω ab will be introduced into the equation. If the transition is too slow, there may be a loss of controllability during the transition.

[0105] The speed difference during commutation can be expressed as ω c,2 -ω c,1=2Δω, assuming that Δω slip is required in the MR fluid clutch device 10 to produce torque in the Δω direction. Assuming constant acceleration and ignoring motor electrical response, the slip commutation time may be affected by the gear motor acceleration Limitations:

[0106]

[0107] For perceptible commutation, the required motor commutation time can be less than the required torque time response of the actuator:

[0108] Δt<<τ r

[0109] where the time response of the actuator is related to the (applied -3dB desired force command) actuator's resistance bandwidth (in Hz):

[0110]

[0111] Therefore, for an imperceptible slip transition for a given application, a minimum gearmotor acceleration is required:

[0112] α gm >>5.7Δωf 3dB

[0113] If Δω = 10i (in RPM, or Δω = 1.05i in rad / s), and if the maximum force perceivable by the human body is in the bandwidth of 20 Hz, the acceleration of the gear motor can be

[0114] For hard-to-perceive transitions, the transition can be made in the constant torque range where acceleration is maximum. The input reduction ratio 84 can be kept as low as possible. Therefore, the selection of the motor / input reduction ratio 84 is critical for seamless sliding direction changes. For example, when with r p = 4:1 input reduction ratio 84 coupling, the torque and inertia ratio of the given motor Down to and may become perceptible. In contrast, another motor may be driven at an input reduction ratio of 84r p = 1:1 operation, and has The torque to inertia ratio is within the range, thus providing strong potential for seamless shifting. The values ​​used here are provided for general illustration purposes only and do not necessarily reflect actual device values.

[0115] As the example shows, the minimum gear motor dynamics may not always match the system requirements. Figure 4An antagonistic MR fluid system using two counter-rotating MR fluid clutch devices 10A and 10B (which should remain antagonistic) as in may exhibit fewer reversing events because one MR fluid clutch device 10 may be in a slipping condition in each direction relative to the output, thereby providing the best motion control performance. Such an antagonistic MR fluid system may not exhibit reversing events under some conditions. However, in order to limit the weight and cost of such a system, it may be advantageous to design a system that allows reversing. It may also be advantageous to design an antagonistic MR fluid system with some acceleration limitations in the two counter-rotating MR fluid actuator units and / or MR fluid clutch devices in order to limit the power consumption of such a system. This may make sense for a haptic device such as a force feedback aircraft manipulator that uses a single motor connected to two antagonistic clutches and where it is necessary to limit the system weight, so a light motor connected to the MR fluid clutch devices 10 and 10' through a high ratio input gearbox 22 is used, but such a system may not exhibit all the best capabilities in terms of acceleration because the reflected inertia of the motor is relatively high at the input member 12 of the MR fluid clutch device 10. In such a system, the human body may move faster than the acceleration capability of the haptic device, and a desired sliding condition may reverse and reach a condition that is undesirable from a force direction perspective. In another condition, the human body may be moving faster than the maximum velocity capability of the haptic device, and sliding reversal may also occur.

[0116] like Fig. 20 A motion control system using only one motor 21 and one MR fluid clutch device 10 as in FIG. 14 and a reconfigurable motion control system using multiple motor / MR fluid clutch chains as in FIG. 18 , which can switch between antagonistic operation and combined operation, may inevitably face reversing events and may therefore be hindered by the dynamics of the combination of the motor 21 and the input reduction mechanism 84.

[0117] In a variation, the present disclosure describes a method for minimizing controllability loss during commutation when the combined dynamics of the motor 21 and the input reduction mechanism 84 are slower than the motion system requires.

[0118] Fig. 22 It shows Figure 3 The limitations of the single-motor single-clutch active suspension system in Figure 4 or Figure 5 Figure 1 shows a dual clutch system. Fig. 20An electromechanical actuator such as that in the embodiment of the present invention consists of an electric motor 21 attached to a reduction mechanism and a rotation-translation conversion mechanism (e.g., a linkage, a rack and pinion or a ball screw, etc.). If a low reduction ratio is selected, the parasitic forces are low, but the electric motor 21 must be bulky and heavy to produce the required torque. Alternatively, if a high reduction ratio is selected, the motor 21 and the reduction system can be light and compact, but the parasitic forces may be high. Because in the automotive industry, volume and mass must be minimized, electromechanical actuators on the market may be highly geared, i.e., have a high reduction ratio. In order to cope with high parasitic reaction forces, manufacturers can resort to using series elastic elements between the actuator and the wheel, such as in the case of vehicles. This reduces parasitic forces and prevents the actuator from exhibiting high internal reaction loads during impact, but it also reduces the force bandwidth of the actuator. This is why rotary electromechanical actuators typically exhibit slow responsiveness (<10Hz). This may limit its performance potential. By combining a highly reactive device like the MR fluid clutch apparatus 10 with a torque-intensive and power-intensive highly geared drive train, a system that is both torque-intensive and power-intensive with low back-drive force and fast acting can be obtained. Such a system is described in International Patent Application Publication No. WO 2016 / 187719, which is incorporated herein by reference.

[0119] When controlling a single motor single clutch system such as Fig. 20In the system in which the MR fluid clutch device 10 filters out the high inertia of the motor 21 and the gear train consisting of the pinion 203 and the rack 204 and transmits the force in the correct direction), the MR fluid clutch device 10 may need to maintain slippage. The input 14 of the MR fluid clutch device 10 needs to rotate faster than the output 11 of the MR fluid clutch device 10. Therefore, the motor 21 always has to maintain slippage in the appropriate direction so that the actuator generates the corresponding force in the desired direction. When driving on the road, it may be difficult to predict or anticipate all obstacles that will affect the output of the active suspension including the MR fluid clutch device 10. Sometimes, the motor 21 cannot maintain the correct amount of slippage in the MR fluid clutch device 10. For example, an obstacle (e.g., a bump, a pothole, ...) may cause the output 201 of the active suspension to accelerate at a higher rate than the highly geared transmission system can achieve. This may be due to the low bandwidth, high inertia, and / or limited torque of the highly geared power source of the motor 21 and the input reduction mechanism 84 (e.g., gearbox, belt system), particularly during a change in the direction of rotation of the motor 21 (if bidirectional). Additionally, the designer may wish to limit the motor reversing acceleration torque to reduce the weight of the strut components. In such a situation, the output 11 of the MR fluid clutch device 10 may spin faster than the input 14 of the MR fluid clutch device 10, and thus the MR fluid clutch device 10 may drive the motor 21 in the wrong direction and further delay the change of direction of the motor 21. In other words, in such a reversing situation, the direction of the force applied by the MR fluid clutch device 10 to the electric motor 21 will also reverse before the motor 21 changes direction, and will be in the opposite direction of the commanded force. In Fig. 22 In the left figure of , this may occur when the slip condition becomes 0, with a slip condition of 1 indicating the correct direction. When this occurs, stopping the torque transfer of the MR fluid clutch device 10 may present an advantage in order to minimize the command force compared to the achieved or measured force. To do this, the MR fluid clutch device 10 is controlled to provide zero torque. Different methods can be used to achieve this, such as: shutting down the MR fluid clutch device 10; maintaining high slip during a delay period; delaying the response of the MR fluid clutch device 10 to a frequency similar to that of the motor 21; switching control of the MR fluid clutch device 10 to a passive damper. This is in contrast to other active suspension systems, where in order to minimize the difference between the desired force and the measured force, it may be necessary to increase the power of the system to a maximum value. This particular function of the active MR fluid suspension system may be referred to as a let-go function. The effect of the let-go function can be seen in Fig. 22, where the force command for the MR fluid clutch device 10 is shown as 0 (equal to 0) when the slip condition is reversed. On a dual MR fluid clutch device system where the motor 21 does not have to reverse its direction (e.g., the motor 21 can be unidirectional), in order to provide torque in the correct direction, a higher slip can be maintained in the MR fluid clutch device 10, and zero torque is unlikely to occur. In the example of a system with a dual MR fluid clutch device configuration shown, a higher slip condition between the input 14 and the output member 11 of the MR fluid clutch device 10 can ensure that there is no reversal. In the case of a single motor single clutch system, the situation is even worse because lower slip is desired in order to reduce the time it will take for the motor to switch from one direction to the other. For example, in the case of a reduction ratio 84 of 10 to 1 between the motor 21 and the MR fluid clutch device 10, in order to maintain a slip of 200 RPM in the MR fluid clutch device 10, the motor 21 needs to rotate at 2000 RPM. When the force direction is desired to change, in order to maintain 200RPM slip in the MR fluid clutch device 10, the motor must overcome the inertia created by the motor 21 and go from 2000RPM to -2000RPM. To increase the mechanical bandwidth of such a single motor single clutch system, limiting the slip in the MR fluid clutch device 10 may present advantages. When doing so, the likelihood that the road will cause the output member 11 to accelerate more than the input member 14 can accelerate when driven by the motor 21 increases, so the let-go function may be more useful than in the case of a dual clutch system, for which the motor 21 may not have to reverse its direction in a dual clutch system, so that greater slip can be maintained. Anticipating road disturbances using pre-visualization techniques (e.g., LiDAR) or road digitization can help reduce the number of events where the let-go function may be used, because the slip rate can be increased in the correct direction in advance of the planned event so that the system has sufficient slip in the MR fluid clutch device 10 to cope with the upcoming situation. However, the let-go function may still be used when the obstacle provides a movement speed greater than the maximum design speed of the MR fluid actuator design. The hands-off functionality may still help to maintain the maximum speed of the system at a level that allows the MR fluid actuator to remain within acceptable weight and size constraints.

[0120] Fig.23 As an example, Figure 6Graph of typical motor 21 current for a single motor single clutch active suspension compared to a single motor dual clutch suspension over the same cab floor disturbance in an embodiment. A disadvantage of a single motor single clutch system may be that the motor 21 must change its direction very frequently, such as multiple times per second. This high switching frequency may cause the motor 21 to have a large current demand to quickly switch directions. Therefore, in some cases, the single motor single clutch system may consume more average energy than a dual clutch system. Using the hands-off function can reduce the current demand.

[0121] Therefore, a system for operating a magnetorheological (MR) actuator unit between bodies (such as Fig. 20 ) may include an MR fluid actuator unit including a bidirectional motor assembly and an MR fluid clutch device, the bidirectional motor assembly operating within a first frequency range, the MR fluid clutch device connected to the bidirectional motor assembly to apply a variable amount of force from the bidirectional motor between at least two of the bodies, the MR fluid clutch device operating within a second frequency range, the second frequency range being higher than the first frequency range. The sensor provides data indicative of a state of one or more of the bodies. Thus, a controller of the system may perform actions such as: receiving data from the sensor; determining from the data the magnitude and direction at which the bidirectional motor assembly must be accelerated or decelerated to control the relative velocity between the input and output of the MR fluid clutch device to transfer a desired force between the bodies; controlling the bidirectional motor to accelerate or decelerate to a given value in the first frequency range, and simultaneously reducing torque transfer during a hysteresis period in which torque transfer from the MR fluid clutch device acts opposite to the desired force.

[0122] Because the MR fluid clutch device 10 generally operates at a higher frequency range than the frequency range of the bidirectional motor assembly (e.g., including the motor 21 and the reduction mechanism 84, particularly because of inertia, backlash, etc.), in some circumstances, the force transfer may be opposite (i.e., opposed) to the desired force transfer on the output 11. For example, in response to a disturbance experienced by the system, the controller may determine that the motor assembly must be accelerated or decelerated to a given value (e.g., a greater or lesser speed), or the direction of rotation may be reversed. The motor assembly is then controlled to accelerate or decelerate to the given value, but can only do so within its frequency range (which is smaller than the frequency range of the MR fluid clutch device 10). As a result, the MR fluid clutch device 10, which transfers force between the input 12 (i.e., the motor 21) and the output 11, may react faster than the motor 21. In such circumstances, the torque transfer of the MR fluid clutch device 10 may result in an inappropriate slip direction during the hysteresis period, i.e., the output 11 will act on the input 12 in a direction opposite to the desired direction. Thus, the controller may reduce torque transfer during this hysteresis period when torque transfer from the MR fluid clutch device acts against the desired force, for example, to compensate for a mismatch in operating frequency ranges.

[0123] Fig.24 An exemplary total power consumption of a single motor single clutch system is shown. The motor 21 consumption of a single motor single clutch system may generally be higher than one of a dual clutch system. However, taking into account all losses in the MR fluid clutch device 10 (and the dual clutch system 10 ′), the total power consumption of the single motor single clutch system may be lower, such as Fig.24 This is true for both cases shown. The platform vibration levels for a single motor single clutch system may also not differ significantly from those for a dual clutch system. Although a large number of motor direction changes may be required, it may be advantageous to integrate a single motor single clutch system into an active suspension in order to reduce the energy consumption of the active suspension system. This may be important for any application that runs on batteries, such as active suspension for electric vehicles.

[0124] Fig.25 Shows Fig. 20 The "hold slip" function of a single motor single clutch system. When a single motor single clutch system is used, a large number of motor commutations may introduce noise and vibration into the mechanical system. The noise and vibration may come from the high acceleration and deceleration reaction forces of the electric motor and / or from the backlash of the mechanical system. This may be referred to as noise, vibration and harshness (NVH), which can be perceived by people around the system, so it may be desirable to reduce NVH. A novel way to minimize the NVH of an active suspension using a single MR fluid clutch device is to limit the number of MR fluid actuator slip commutations. In order to limit the MR fluid actuator slip commutations, the controller of the active suspension can operate a "hold slip" zone. The "hold slip" zone can keep the slip direction generated by the motor 21 between the input member 14 and the output member 11 in the wrong direction for a limited period of time, instead of operating the MR fluid clutch device 10 to transmit the commanded torque. The "hold slip" zone can be defined within the force command, input speed command, and / or output speed command amplitude. In other words, when optimal performance is expected, the slip direction within the MR fluid clutch device 10 will not be executed immediately, but will lag. In this region, such hysteresis may be desired in order to limit the number of reversals of sliding direction within the MR fluid clutch device 10 and reduce the acoustic harshness of the reversals. Less load reversals within the MR fluid clutch device 10 will produce less force direction changes and therefore less NVH. However, when the goal of the active suspension is to achieve optimal vibration and movement reduction, such hysteresis functionality may introduce more torque error and its use may be counterintuitive. Nevertheless, during implementation, reducing the performance of the active suspension system in order to reduce the acoustic harshness generated may still present advantages, thereby providing a better overall experience for people around the system inside or outside the vehicle, even if the vibration and movement reduction achieved by the active suspension is lower.

[0125] "Keep Sliding" feature like Fig.25 , where the slip is locked to one side with intentional hysteresis until the commanded torque exceeds a given value in the opposite direction. This is just one control algorithm, and other control algorithms can also be used to control hysteresis and limit the number of commutations (e.g., model predictive control (MPC), AI, pre-visualization of obstacles using cameras, to name a few). Fig.25 In the , the hold slip zone is shown as being approximately from -0.5Nm to 0.5Nm, but this value is not fixed for a given active suspension system. The value of the "hold slip" zone can be dynamically adjusted based on the operating conditions of the active suspension system.

[0126] According to a variation, the "hold slip" function may be operated by a system for operating a suspension between a mass and a structure, the system may include: a bidirectional motor, such as 21; a magnetorheological (MR) fluid clutch device, such as 10, which couples the bidirectional motor 21 to the mass to apply force from the bidirectional motor to the mass. This may be in a single clutch, single motor arrangement. Sensors provide data indicative of the state of the mass and / or structure. A controller of the system may have: a processing unit; and a non-transitory computer readable memory, communicatively coupled to the processing unit and including computer readable program instructions executable by the processing unit for: receiving data from the sensor; determining a desired torque amplitude to be produced by the bidirectional motor based on the data; keeping the bidirectional motor off if the desired torque amplitude is below a torque amplitude threshold, and enabling the bidirectional motor if the desired torque amplitude is above the torque amplitude threshold.

[0127] The hysteresis function and value introduced in the "hold slip" function allows minimizing the punishing force tracking ability of the active suspension when the system is in the hold slip zone while keeping NVH to acceptable levels. Fig. 20 Single motor single clutch system, or for Fig.15 , Figure 16, Figure 18 or Fig.19 This may be useful for a dual motor dual MR fluid clutch device such as that. Reversing the sliding direction in the MR fluid clutch device 10 of a single motor single clutch system or the MR fluid clutch device 10 or 10' of a dual motor dual clutch system may require that the input member 12 speed ω of the MR fluid clutch device 10 or 10' c,1 or c,2 One of them increases or decreases so that they are connected to each other at the same speed ω a The rotating output speed member 11 or 11' reverses the sliding direction. If the reversing time is too slow, controllability may be lost during the reversing period.

[0128] Fig.26Shows Fig. 20 The single motor single clutch system of FIG14 shows a combination of the “let go” function and the “keep sliding” function, but these functions can be operated independently, i.e. with one function but without the other. When an external disturbance causes the output of the active suspension system to accelerate faster than the input, the “keep sliding” function may increase the number of occurrences where the “let go” function will be used because it will increase the chance that the motor will turn in the opposite direction. It is shown at times 14.0, 14.8 and 15.1. Nevertheless, there is a great benefit in using a combination of both the “let go” function and the “keep sliding” function because a single motor single clutch system can be implemented at a lower cost than a dual clutch system and the amount of NVH is kept at an acceptable level, although the performance of the active suspension is not at its maximum.

[0129] During driving, it may be advantageous for the user to select the level of the "hold slide" function. In normal driving, the function may be kept at an acceptable level to limit NVH, and in more aggressive driving, the driver may decide to switch the function off completely to achieve maximum performance of the active suspension system, albeit with increased levels of NVH generated. For example, on gravel roads, where noise levels are high due to friction between the loose material and the tires, it may be desirable to switch off the "hold slide" function, particularly since on such roads the frequency of active suspension interventions may be increased.

[0130] A single motor single clutch system can be used as an active suspension system, but can also be used as an energy harvesting suspension only. The active suspension can then be considered semi-active, since there is no energy injection in the active quadrant (see Fig. 9 ), and in the passive quadrant there is only energy dissipation, with or without energy recovery.

[0131] When using a system featuring multiple MR fluid clutch devices 10, such as Figure 4 , Figure 5 , Fig.15 , Fig.16a , Fig.18a , Fig.19 As shown, it can be applied with Figure 3 and Fig. 20The same logic is used for the single MR fluid clutch device 10 system shown. In those systems with multiple MR fluid clutch devices 10, there may be situations where the minimum gear motor dynamics cannot always match the system requirements. In such an antagonistic MR fluid system using two counter-rotating MR fluid actuator units, under some conditions, the two MR fluid clutch devices 10 may not always remain antagonistic. One MR fluid clutch device 10 may exhibit a reversing event, causing the two MR fluid clutch devices 10 to slip in the same direction relative to the output, and therefore will not provide optimal motion control performance. Under such conditions, the use of the release function and the keep slip function can effectively improve system behavior and reduce NVH or unexpected forces. This condition may be caused by the lack of ability of one of the motors to produce the best desired acceleration. This condition may also be caused by the limitation imposed on one or more motor accelerations in order to limit the power consumption or peak power of the MR fluid actuator. It is well known that high motor accelerations may require high currents in the motor coil windings. Since the Joule losses in the coil windings of the motor are the square of the current, it should be understood that limiting the current in the coil windings will also limit the Joule losses, thereby limiting the power consumption of the device and the heat generated in the device. It should be noted that these Joule losses may not even produce useful work at the actuator output in some cases. For example, if the system is energized when the command force is zero, then one or more motors may still have to track the output velocity in order to maintain the ability of the actuator to produce force in the correct direction when needed. This tracking alone from the one or more motors may require high acceleration and power from the one or more motors, so limiting the acceleration of the one or more motors may be beneficial. Limiting the current can be for power consumption limitation, heat generation, or both. The previous explanation is also valid for other configurations, such as Fig.16b and Fig.18b , where one MR fluid clutch device 10 is connected to the motor and where another MR fluid clutch device 10' is grounded on the chassis to act as a brake. In such a configuration, it may also happen that the minimum gear motor dynamics cannot always match the system output requirements. Therefore, the controller of a system with multiple MR fluid clutch devices 10 can operate a hands-off function and / or a hold slip function.

[0132] In any of the proposed configurations, using the hands-off function at a time before a slip reversal situation actually occurs may present advantages. This can help the system cope with events that may occur faster than the mechanical bandwidth of the MR fluid clutch device 10. This may also be useful if an event occurs or may occur at a rate faster than the calculation speed of the controller 64. For example, if the acceleration of the output member 11 or any other component of the output of the MR fluid actuator is measured to exceed the reaction capacity of the MR fluid clutch device 10 or the controller 64, reducing the torque of the MR fluid clutch device 10 at a time before slip reversal occurs to reduce the risk of torque reversal may present advantages. It may also be desirable to reduce the risk of transient torque cutoff (torque changes from a given torque to 0) that may produce NVH. In some cases, it may be advantageous to control the torque reduction linearly or nonlinearly relative to measured or calculated parameters (including the measured or calculated slip between the input member 12 and the output member 11 of the MR fluid clutch device 10). Such linear functions and nonlinear functions are described in detail in detail. Fig.27a , for illustration purposes only. As long as the slip target is met, the system can provide the best calculated torque, represented here by a torque amplifier of 1. When the slip target is below a threshold, the torque command or amplifier is gradually reduced to reach 0 when there is no more slip in the MR fluid clutch device. As long as there is slip in the MR fluid clutch device in the direction opposite to the desired direction, the command torque remains at zero. Figure 27b In the example, zero command may be reached while the sliding direction is still in the desired direction to ensure that rapid acceleration or delays in the controller do not induce forces in undesired directions. The shape of the linear or nonlinear function may be dynamically adapted during operation based on measured or calculated parameters.

[0133] refer to Fig.28 , the controller 64 is shown having one or more processing units 64A, a non-transitory computer readable memory 64B communicatively coupled to the processing units and including computer readable program instructions executable by the processing units 64A for performing the operations described above and in the MR fluid actuators described herein using data from the sensors 62 associated with any one or more of the MR fluid actuators described herein. Fig.28280. The controller 64 may drive any MR fluid clutch device 10 and / or drive its motor 21. For example, the controller 64 may be operable to: receive data from at least one sensor; determine from the data the magnitude and direction of the relative velocity between the input and output of the MR fluid clutch device that the motor assembly must accelerate or decelerate to control the magnitude and direction of the relative velocity between the input and output of the MR fluid clutch device to transmit the desired force between the bodies; control the motor assembly to accelerate or decelerate to a given value at a first frequency range, and simultaneously reduce torque transmission during a hysteresis period during which torque transmission from the MR fluid clutch device acts against the desired force. In some variations, reducing torque transmission includes closing the MR fluid clutch device; reducing torque transmission includes delaying the response of the MR fluid clutch device during the hysteresis period; reducing torque transmission includes delaying the response of the MR fluid clutch device during the hysteresis period when the system remains within a predefined operating zone; determining from the data the magnitude and direction of the relative velocity between the input and output of the MR fluid clutch device that the motor assembly must accelerate or decelerate to control includes controlling the magnitude and direction of the relative velocity between the input and output of the MR fluid clutch device to transmit the desired force between the bodies. In variations, the hysteresis period corresponds to a duration during which an absolute slip velocity of the MR fluid clutch device is less than a desired slip threshold. The controller 64 can be used to determine a desired speed magnitude to be generated by the bidirectional motor based on the data; if the desired absolute torque magnitude is within a torque magnitude threshold, maintain the slip in the MR fluid clutch device to maintain the current direction and not respond to the desired slip speed magnitude reversal, and if the desired absolute torque magnitude exceeds the torque magnitude threshold in the opposite direction, reversing the slip speed of the MR fluid clutch device. The controller 64 can also be used to receive data from at least one sensor; determine the bidirectional motor switching direction based on the data; and when the slip is not in the desired direction, simultaneously control the bidirectional motor to reduce the torque transmission from the MR fluid clutch device.

Claims

1. A system for operating a magnetorheological (MR) fluid actuator unit between bodies, comprising: at least one MR fluid actuator unit including a motor assembly operating within a first frequency range and a MR fluid clutch device connected to the motor assembly to apply a variable amount of force from the motor assembly between at least two of the bodies, the MR 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 status of at least one of the subjects; Processing unit; as well as a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit for: receiving said data from said at least one sensor; determining, based on the data, a magnitude and direction at which the motor assembly must be accelerated or decelerated to control a relative velocity between an input and an output of the MR fluid clutch device to transmit a desired force between the bodies; controlling the motor assembly to accelerate or decelerate toward a given value within the first frequency range, and Concurrently, the torque transfer from the MR fluid clutch device is reduced during a hysteresis period in which the torque transfer acts opposite to the desired force.

2. The system according to claim 1, wherein: The motor assembly includes a motor and a reduction mechanism.

3. The system according to any one of claims 1 and 2, wherein: Reducing the torque transfer includes closing the MR fluid clutch device.

4. The system according to any one of claims 1 to 3, wherein: Reducing the torque transfer includes delaying a response of the MR fluid clutch device during the hysteresis period.

5. The system according to any one of claims 1 to 4, wherein: Reducing the torque transfer includes delaying a response of the MR fluid clutch device during the hysteresis period while the system remains within a predefined operating zone.

6. The system according to any one of claims 1 to 5, wherein: The motor assembly includes at least one unidirectional motor.

7. The system according to any one of claims 1 to 5, wherein: The motor assembly includes at least one bi-directional motor.

8. The system according to claim 7, wherein: Determining from the data that the motor assembly must accelerate or decelerate to control magnitude includes controlling the direction of relative velocity between the input and the output of the MR fluid clutch device to transfer the desired force between the bodies.

9. The system of any one of claims 7 and 8, comprising two of the MR fluid actuator units, each having a bidirectional motor connected to a respective one of the MR fluid clutch devices, the two MR fluid actuator units controlling the desired force on a common output.

10. The system according to any one of claims 1 to 9, wherein: A first of the bodies is a mass and a second of the bodies is a structure.

11. The system according to claim 10, wherein: The structure is suspended from the mass.

12. The system according to any one of claims 1 to 11, wherein: The system is an active suspension that generates energy in the passive quadrant.

13. The system according to any one of claims 1 to 12, wherein: The system is an active suspension that uses energy in the active quadrant.

14. The system according to any one of claims 1 to 9, wherein: The main body is the connecting rod of the robot.

15. The system of claim 14, wherein: The robot is a collaborative robot.

16. The system according to any one of claims 1 to 9, wherein: The main body is the fixed chassis and the haptic device.

17. The system of claim 1, wherein: The hysteresis period corresponds to a duration during which an absolute slip velocity of the MR fluid clutch device is less than a desired slip threshold.

18. The system according to claim 7, comprising: determining a desired speed magnitude to be produced by the bidirectional motor based on the data; If the desired absolute torque magnitude is within a torque magnitude threshold, maintaining slip in the MR fluid clutch device to maintain in a current direction and not responding to the desired slip speed magnitude reversal, and if the desired absolute torque magnitude exceeds the torque magnitude threshold in an opposite direction, reversing the slip speed of the MR fluid clutch device.

19. A system for operating a suspension between a mass and a structure, comprising: Bidirectional motor; a magnetorheological (MR) fluid clutch device coupling the bi-directional motor to the mass to apply a force from the bi-directional motor to the mass; at least one sensor for providing data indicative of said mass and / or state of said structure; a processing unit; as well as a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit for: receiving said data from said at least one sensor; determining a desired speed magnitude to be produced by the bidirectional motor based on the data; If the desired absolute torque magnitude is within a torque magnitude threshold, maintaining slip in the MR fluid clutch device to maintain the current direction and not responding to the desired slip velocity magnitude reversal, and If the desired absolute torque magnitude exceeds the torque magnitude threshold in the opposite direction, the slip speed of the MR fluid clutch device is reversed.

20. A system for operating a suspension between a mass and a structure, comprising: a bidirectional motor operating within a first frequency range; a magnetorheological (MR) fluid clutch device coupling the bi-directional motor to the mass to apply a force from the bi-directional motor to the mass, the MR 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 said mass and / or state of said structure; a processing unit; as well as a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit for: receiving said data from said at least one sensor; Determining the switching direction of the bidirectional motor according to the data; The bi-directional motor is simultaneously controlled to reduce torque transfer from the MR fluid clutch device when slip is not in a desired direction.

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