WO2018027532A1

WO2018027532A1 - Device and method for coordinating magnetorheological damping/braking and energy harvesting

Info

Publication number: WO2018027532A1
Application number: PCT/CN2016/094124
Authority: WO
Inventors: Weihsin Liao; Chao Chen
Original assignee: The Chinese University Of Hong Kong
Priority date: 2016-08-09
Filing date: 2016-08-09
Publication date: 2018-02-15

Abstract

A device and method for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) in an MR damping/braking system (3000). The device comprises a divider (3110) configured to generate a first allocating signal and a second allocating signal based on a desired overall damping force/braking torque; an MR damping/braking controller (3120) configured to generate, in response to the first allocating signal, an MR command signal for generating an allocated MR damping force/braking torque; and an EH controller (3130) configured to harvest an allocated energy in response to the second allocating signal.

Description

DEVICE AND METHOD FOR COORDINATING MAGNETORHEOLOGICAL DAMPING/BRAKING AND ENERGY HARVESTING

Technical Field

The present application relates to a device and method for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) in an MR damping/braking system.

Background

MR fluids are one kind of smart materials that exhibits fast, reversible and tunable transition from a free-flowing state to a semi-solid state in a few milliseconds, upon application of a magnetic field. MR fluids are very promising for semi-active vibration/braking control because they provide a simple and fast response interface between electronic controls and mechanical devices/systems.

Fig. 1 illustrates the schematic of a typical MR damping system with a semi-active control system. As shown in Fig. 1, the MR damping system 100 comprises a dynamic sensor 110, a system controller 120, a damper controller 130, a current driver 140, an MR damper 150, and a plant 160. The dynamic sensor 110 is used to measure signals such as displacement, velocity and/or acceleration of the plant 160. The system controller 120 may generate and output a signal representing the desired damping force of MR damper 150 according to the measured signals. Then, the damper controller 130 will generate a command of voltage based on the measured signals and the desired damping force. With the command of voltage, the current driver 140 will transmit a driving current which can drive the MR damper 150 to generate the desired damping force applied to the plant 160. If the MR damping system 100 further comprises a force sensor (not shown in Fig. 1) , the damper controller 130 will run a closed-loop force control algorithm by using the generated forces measured by the force sensor, so as to realize a closed-loop force control. Similarly, if the MR damping system 100 further comprises a current sensor (not shown in Fig. 1) , the damper controller 130 will run a closed-loop current control algorithm by using the generated current measured by the current sensor, so as to realize a closed-loop current control.

For the normal working of an MR damping system, an electrical power supply is required to activate electromagnetic coils inside or outside the MR damper to provide a magnetic field for the MR fluids. However, a large amount of mechanical energy are wasted and dissipated in the MR damping system. To harvest and reuse the wasted mechanical energy, there were some efforts put on the development of MR damping systems with power generation, i.e., energy harvesting capability. An energy harvester in the MR system will convert kinetic energy into electrical energy, to improve the energy efficiency of the entire system.

Fig. 2 illustrates the schematic of another typical MR damping system with an energy harvesting capability. For the purpose of conciseness, the detailed description of the components in Fig. 2, which are the same as those in Fig. 1, will be omitted. As shown in Fig. 2, the MR damping system 100’ further comprises a power generator 170 and an energy harvester 180. The power generator 170 as a working mechanical part can convert mechanical energy from the MR damper into electrical energy which can be stored in the energy harvester 180. With the power generator 170 and energy harvester 180, it is possible for the system 100’ to have both MR damping and energy harvesting capabilities.

However, the MR damping and energy harvesting in a single system may affect each other. Taking a vehicle suspension system as an example, the purpose of the MR damper is to eliminate or mitigate the vibration so as to have a good vibration-isolation performance and provide good ride comfort. Generally, the MR damping function prefers to make the motion of the suspension small. However, the purpose of energy harvesting is to harvest the vibratory energy as much as possible. Therefore, the energy harvesting function prefers a large motion in amplitude for the suspension. As a result, the objectives of these two functions are different from and contrary to each other.

On the one hand, the energy harvesting will induce an additional damping force to the plant, directly or indirectly. The damping effect from the energy harvesting can be considered as a variable viscous damper. The additional damping force is generated from the induced electrical energy of the power generator according to the law of energy conversion, and will be applied to the vibrating structure, directly. And, the additional damping force is variable as the variance of excitation velocity of the plant or MR damper, depending on the position of the power generator. As shown in Fig. 2, the power generator 170 is connected to the MR damper 150, directly. Thus, the damping force from the energy harvesting will applied to the MR damper 150, directly, and to the plant 160, indirectly. If the power generator 170 is directly connected to the plant 160, the damping force from the energy harvesting will applied to the plant 160, directly.

Since both of the energy harvesting and MR damping can produce damping forces, the effect of energy harvesting will affect the vibration/motion control performances. On the other hand, the MR damping control will affect the system dynamic responses, that is, the input excitation of the energy harvesting. Thus, the effect of MR damping will affect the energy harvesting ability as well.

There are lots of vibration/motion control methods for MR damping devices/systems, such as the skyhook control. However, the existing vibration/motion control apparatus and methods are only for the control of MR damping, without considering the interaction between the MR damping and the energy harvesting. In addition, the existing vibration/motion control apparatus and methods have not considered how to maximize the harvested energy, while satisfying the vibration/motion control performance.

Summary

According to an aspect of the present application, a device for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) in an MR damping/braking system is provided. The device comprises: a divider configured to generate a first allocating signal and a second allocating signal based on a desired overall damping force/braking torque； an MR damping/braking controller configured to generate, in response to the first allocating signal, an MR command signal for generating an allocated MR damping force/braking torque； and an EH controller configured to harvest an allocated energy in response to the second allocating signal.

According to another aspect of the present application, a method for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) in an MR damping/braking system comprises: allocating a desired overall damping force/braking torque in the MR damping/braking system into a desired MR damping force/braking torque and a desired EH damping force/braking torque； generating an allocated MR damping force/braking torque according to the desired MR damping force/braking torque； and harvesting an allocated energy according to the desired EH damping force/braking torque.

According to embodiments of the present application, the MR damping/braking and the EH in an MR damping/braking system is coordinated, in consideration of the interaction therebetween. With the device having a divider, the desired overall damping force/braking torque can be divided into two parts, namely, the allocated MR damping force/braking torque and the allocated energy. The allocated MR damping force/braking torque may ensure the damping/braking control performance, firstly. Then, the allocated energy may maximize the energy efficiency. As such, not only the damping/braking control performance can be ensured, but also the mechanical energy can be harvested as much as possible while reducing the electrical power consumption for MR damping/braking. The interaction between the MR damping/braking and EH are fully considered.

Brief Description of the Drawings

Fig. 1 illustrates the schematic of a typical MR damping system with a semi-active control system；

Fig. 2 illustrates the schematic of another typical MR damping system with an energy harvesting capability；

Fig. 3 illustrates the schematic of an MR damping/braking system having a device for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) of the system, according to an embodiment of the present application；

Fig. 4 illustrates the schematic of an EH controller according to an embodiment of the present application；

Fig. 5 illustrates the schematic of an EH circuit according to an example of the present application；

Fig. 6 illustrates the schematic of an EH circuit according to another example of the present application；

Fig. 7 illustrates the schematic of an EH circuit according to a further example of the present application；

Fig. 8 is a flowchart illustrating a method for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) in an MR damping/braking system according to an embodiment of the present application；

Fig. 9 is a flowchart illustrating the step S810 according to an embodiment of the present application；

Fig. 10 illustrates an example of the application to be applied to a vehicle suspension system； and

Fig. 11 illustrates another example of the application to be applied to an intelligent prosthetic system.

Detailed Description of Embodiments

Hereinafter, a detailed description of the present application will be given with reference to the appended drawings.

MR damping devices/systems described herein may include MR dampers and MR brakes. The MR dampers, such as vehicle suspension systems, work in the conditions of linear motion. In such an MR damper, it will generate a damping force for the system. The MR brakes, such as intelligent knee prostheses, work in the conditions of rotary motion. In such an MR brake, it will generate a braking torque for the system. It should be noted that the MR damping device/system described in this specification may include both of the MR damper and the MR brake.

Fig. 3 illustrates the schematic of an MR damping/braking system having a device for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) of the system, according to an embodiment of the present application. As shown in Fig. 3, the MR damping/braking system 3000 comprises a dynamic sensor 110, a system controller 120, a current driver 140, an MR damper 150, a plant 160, a power generator 170, and a device 3100 for coordinating MR damping/braking and EH. For the purpose of conciseness, the detailed description of the components in Fig. 3, which are the same as those in Fig. 2, will be omitted.

Referring to Fig. 3, the device 3100 comprises a divider 3110, an MR damping/braking controller 3120, and an EH controller 3130. In operation, the system controller 120 may generate and output a signal representing a desired overall damping force/braking torque according to a signal measured by the dynamic sensor 110. Based on the desired overall damping force/braking torque, the divider 3110 generates a first allocating signal and a second allocating signal. These two signals will be used for the MR damping/braking and the EH in the system, respectively. The physical circuit for the divider 3110 may be a micro control unit (MCU) , a digital signal processor (DSP) , or the like.

The first allocating signal is transmitted to the MR damping/braking controller 3120. In response to the first allocating signal, the MR damping/braking controller 3120 generates an MR command signal for generating an allocated MR damping force/braking torque. For example, the MR command signal may be a voltage signal, but is not limited thereto. With the MR command signal, the current driver 140 will transmit a driving current which can drive the MR damper 150 to generate the allocated MR damping force/braking torque applied to the plant 160. To generate the MR command signal, the MR damping/braking controller 3120 may run a known control algorithm, such as the PID control, the adaptive control, or the like.

The second allocating signal is transmitted to the EH controller 3130. In response to the second allocating signal, the EH controller 3130 harvests an allocated energy from the power generator 170.

According to the embodiment of the present application, the MR damping/braking and the EH in an MR damping/braking system is coordinated, in consideration of the interaction therebetween. With the device having a divider, the desired overall damping force/braking torque can be divided into two parts, namely, the allocated MR damping force/braking torque and the allocated energy. The allocated MR damping force/braking torque may ensure the damping/braking control performance, firstly. Then, the allocated energy may maximize the energy efficiency. As such, not only the damping/braking control performance can be ensured, but also the mechanical energy can be harvested as much as possible while reducing the electrical power consumption for MR damping/braking. The interaction between the MR damping/braking and EH are fully considered.

Fig. 4 illustrates the schematic of an EH controller according to an embodiment of the present application. As shown in Fig. 4, the EH controller 3130 comprises an EH circuit 3131 and an EH control part 3132. The EH circuit 3131 can harvest the allocated energy from the power generator 170, under control of the EH control part 3132. In response to the second allocating signal from the divider 3110, the EH control part 3132 switches on/off the EH circuit 3131 or adjust an amount of the allocated energy harvested by the EH circuit 3131.

There are two kinds of controllable EH circuits. One is with a non-adjustable equivalent impedance, and the other is with an adjustable equivalent impedance. The configuration of these two kinds of EH circuits will be described in detail later. In the case with a non-adjustable equivalent impedance, the EH control part 3132 may control the EH of the EH circuit 3131 by switching on/off the EH circuit 3131. In the case with an adjustable equivalent impedance, the EH control part 3132 may control the EH of the EH circuit 3131 by adjusting the equivalent impedance of the EH circuit 3131. By controlling the EH circuit 3131, both the harvested energy and the generated damping force/braking torque from the power generator 170 can be controlled. To generate a switch-on/off or adjustment signal, the EH control part 3132 may also run a known control algorithm, such as the skyhook control, bang-bang control, Lyapunov stability-based control, clipped-optimal control, linear quadratic Gaussian control, neural network control, sliding mode control, etc. Each algorithm uses measurements of the absolute acceleration, velocity, displacement and/or applied forces for determining the control action. The adjustment signal may be a pulse width modulation (PWM) signal with an adjusted duty cycle or a resistance control voltage for adjusting the equivalent resistance of the EH circuit 3131.

As such, with the second allocating signal from the divider, the EH control part may control the EH of the EH circuit by switching on/off or adjusting the EH circuit, which makes the control of the EH in the system possible.

For the electromagnetic EH, the induced damping force F_EH and braking torque τ_EH of the EH can be calculated as below.

where x and θ are excitation displacement and rotation angle respectively, and C_EH and C’_EH are damping coefficients. Both of the damping coefficients are constants related to parameters of the power generator and its transmission ratio, and can be readily calculated. For example, for a rotary electromagnetic generator (motor) with a gear system to amplify the angular velocity, C’_EH may be calculated as below.

where n is the transmission ratio, K_m is the motor speed constant, R_i is the internal resistance of the motor coil, R_EH is the equivalent resistance of the energy harvesting circuit. Usually, R_EH is designed to equal R_i, that is, impedance matching. In this way, the energy harvesting circuit will have the maximum efficiency.

Further, τ_EH can also be expressed in the form of the charging current i_EH of the energy harvesting circuit as below.

τ_EH＝nK_mi_EH (4)

In an embodiment of the present application, the divider 3110 generates the first and second allocating signals according to output modes of the MR damping/braking controller 3120 and the EH control part 3132. Generally, there are two typical output modes for each of the MR damping/braking controller and the EH control part. One is the high-low mode, in which there are only two kinds of outputs (i.e., high and low) for each of the MR damping/braking controller and the EH control part. That is, the output is non-adjustable. For example, the high output may be switch-on, and the low output may be switch-off. The other is the adjustable mode, in which the output of each of the MR damping/braking controller and the EH control part can be continuously adjusted. It can be understood that the MR damping/braking controller 3120 may adopt a conventional algorithm suitable for its output mode, so as to generate the MR command signal. The divider generates the first and second allocating signals according to output modes of the MR damping/braking controller and the EH control part such that the damping/braking control performance of the system can be ensured firstly, and the harvested energy can be as much as possible. This will be explained in detail as below.

In an example of the present application, the MR damping/braking controller 3120 has a high output or a low output. That is, the output of the MR damping/braking controller 3120 is non-adjustable, and can be only high or low. In the circumstances, the divider 3110 will generate the first allocating signal to represent the desired overall damping force/braking torque. That is, the divider 3110 will allocate all of the desired overall damping force/braking torque to the MR damping/braking controller 3120. And, the divider 3110 will generate the second allocating signal according to the high output or the low output of the MR damping/braking controller 3120.

Specifically, where the MR damping/braking controller 3120 has the low output, the divider 3110 generates the second allocating signal with which the EH control part 3132 switches off the EH circuit 3131 or adjusts the amount of the allocated energy harvested by the EH circuit 3131 to its minimum. On the other hand, where the MR damping/braking controller 3120 has the high output, the divider 3110 generates the second allocating signal with which the EH control part 3132 switches on the EH circuit 3131 or adjusts the amount of the allocated energy harvested by the EH circuit 3131 to its maximum.

In a conventional MR damping system such as the systems illustrated in Figs. 1-2, if the MR damper controller adopts a high-low mode, a coarse tuning control of the MR damping is sufficient for the system. In the circumstances, according to the example of the present application, the EH is switched on or adjusted to its maximum when the MR damping/braking controller has its high output. As such, the damping/braking control performance of the system can be ensured, and the harvested energy can be as much as possible, regardless of the output mode of the EH circuit. On the other hand, when the MR damping/braking controller has its low output, the EH is switched off or adjusted to its minimum, so as to ensure the damping/braking control performance, firstly.

In another example of the present application, the output of the MR damping/braking controller 3120 is adjustable. In the circumstances, the divider 3110 will compare the desired overall damping force/braking torque with a sum of an EH force/torque corresponding to a maximum amount of the allocated energy harvested by the EH circuit and MR viscous damping force/braking torque. Here, the MR viscous damping force/braking torque can be calculated. And, for some applications, such as intelligent prostheses, the MR viscous damping force/braking torque is usually very small and can be neglected. The EH force/torque corresponds to a maximum amount of the allocated energy harvested by the EH circuit 3131, and can be preset in or obtained by the divider 3110. That is, the divider 3110 will compare the desired overall damping force/braking torque with the sum. Then, the divider 3110 will generate the first and second allocating signals based on a result of the comparison.

Specifically, on the one hand, the amount of the allocated energy harvested by the EH circuit 3131 has a high level or a low level. Correspondingly, the output of the EH control part 3132 is non-adjustable, and can be only high or low. For example, the high output of the EH control part 3132 may switch on the EH circuit 3131, and the low output of the EH control part 3132 may switch off the EH circuit 3131. With a high output of the EH control part 3132, the allocated energy harvested by the EH circuit 3131 will be at a high level, and with a low output of the EH control part 3132, the allocated energy harvested by the EH circuit 3131 will be at a low level, such as zero. In the circumstances, where the desired overall damping force/braking torque is less than the sum of the EH and MR viscous force/torque, the divider 3110 will generate the first allocating signal to represent the desired overall damping force/braking torque. That is, the divider 3110 will allocate all of the desired overall damping force/braking torque to the first allocating signal. And, the divider 3110 will generate the second allocating signal with which the EH control part 3132 switches off the EH circuit 3131. Moreover, where the desired overall damping force/braking torque is larger than or equal to the sum of the EH and MR viscous force/torque, the divider 3110 will generate the first allocating signal to represent a difference between the desired overall damping force/braking torque and the EH force/torque, and generate the second allocating signal with which the EH control part 3132 switches on the EH circuit 3131. That is, the divider 3110 will allocate the EH force/torque to the second allocating signal and allocate the difference between the desired overall damping force/braking torque and the EH force/torque to the first allocating signal.

On the other hand, the amount of the allocated energy harvested by the EH circuit 3131 is adjustable. Correspondingly, the output of the EH control part 3132 is also adjustable. In the circumstances, where the desired overall damping force/braking torque is less than the sum of the EH and MR viscous force/torque, the divider 3110 will generate the first allocating signal to be zero and generate the second allocating signal with which the EH control part 3132 adjusts the amount of the allocated energy harvested by the EH circuit 3131 to correspond to the desired overall damping force/braking torque. That is, the divider 3110 will allocate all of the desired overall damping force/braking torque to the second allocating signal. Moreover, where the desired overall damping force/braking torque is larger than or equal to the sum of the EH and MR viscous force/torque, the divider 3110 will generate the first allocating signal to represent a difference between the desired overall damping force/braking torque and the EH force/torque, and generate the second allocating signal with which the EH control part 3132 adjusts the amount of the allocated energy harvested by the EH circuit 3131 to its maximum. That is, the divider 3110 will allocate the EH force/torque to the second allocating signal and allocate the difference between the desired overall damping force/braking torque and the EH force/torque to the first allocating signal.

The above describes the generation of the first and second allocating signals in different cases, by which the MR damping/braking and EH in an MR damping/braking system is coordinated. And, the damping/braking control performance of the system can be ensured firstly, and the harvested energy can be as much as possible.

Fig. 5 illustrates the schematic of an EH circuit according to an example of the present application. The amount of the allocated energy harvested by the EH circuit shown in Fig. 5 is non-adjustable, but controllable by having an on-off switch to coordinate with the MR damping/braking. As shown in Fig. 5, the EH circuit 3131’ comprises a rectifier 3131a, a voltage regulator 3131b, a switch 3131c’ , and an energy storage 3131d. The rectifier 3131a may be a bridge rectifier or voltage multiplier, and may rectify the AC voltage transmitted from the power generator 170 to a DC voltage. Then, the voltage regulator 3131b may be an isolated flyback converter or boost converter, and may generate a charging current proportional to the DC voltage, which makes the EH circuit 3131’ behave resistive. The EH circuit 3131’ can be designed to be impedance matching with the internal coil of the power generator 170 such that the EH circuit has the maximum efficiency. The switch 3131c’ may receive an on/off signal from the EH control part 3132. In response to the on/off signal, the switch 3131c’ may connect/disconnect the rectifier 3131a with the voltage regulator 3131b. The switch 3131c’ may be, for example, a relay, MOSFET, or the like. The energy storage 3131d may be a rechargeable battery, a capacitor or a super capacitor, and may store the electrical energy harvested from the charging current for reuse. The configuration of the EH circuit shown in Fig. 5 may achieve the control of a non-adjustable EH. That is, the EH circuit may be switched on or off, and will have two damping force/braking torque: 0 or F_EH/τ_EH as expressed in the above equations (1) - (2) .

Fig. 6 illustrates the schematic of an EH circuit according to another example of the present application. The amount of the allocated energy harvested by the EH circuit shown in Fig. 6 is adjustable. As shown in Fig. 6, the EH circuit 3131” comprises a rectifier 3131a, a voltage regulator 3131b, a PWM controlled switch 3131c” , and an energy storage 3131d. For the purpose of conciseness, the detailed description of the components in Fig. 6, which are the same as those in Fig. 5, will be omitted. The PWM controlled switch 3131c” is connected between the rectifier 3131a and the voltage regulator 3131b, and may receive a PWM signal with a controlled duty cycle from the EH control part 3132. The duty cycle of the PWM signal is under control of the EH control part 3132. In response to the PWM signal with a controlled duty cycle, the PWM controlled switch 3131c” may adjust the charging current from the voltage regulator 3131b. By adjusting the charging current, the equivalent impedance of the EH circuit 3131” can be adjusted. With such a PWM controlled switch 3131c” , the equivalent impedance of the EH circuit 3131 is adjustable such that the amount of the allocated energy harvested by the EH circuit 3131 is adjustable. That is, the EH of the system is adjustable, so as to achieve the control of an adjustable EH. Specifically, by controlling the duty cycle of the PWM signal within the range (0, 100％) , the charging current will be within the range (0, i_EH) . In this way, the EH damping force/braking torque can be controlled continuously within the range (0, F_{EH_max}) .

Fig. 7 illustrates the schematic of an EH circuit according to a further example of the present application. The amount of the allocated energy harvested by the EH circuit shown in Fig. 7 is also adjustable. As shown in Fig. 7, the EH circuit 3131” ’ comprises a rectifier 3131a, a voltage regulator 3131b, an adjustment resistor 3131c” ’ , and an energy storage 3131d. For the purpose of conciseness, the detailed description of the components in Fig. 7, which are the same as those in Fig. 5, will be omitted. As shown in the above equation (3) , the EH damping force/braking torque is inversely proportional to the equivalent resistance of the EH circuit. Thus, the adjustment resistor 3131c” ’ is included in the EH circuit 3131” ’a nd connected to the voltage regulator 3131b, which may receive a resistance adjustment voltage from the EH control part 3132. In response to the resistance adjustment voltage, the adjustment resistor 3131c” ’ may adjust the charging current by adjusting the resistance of itself. With such an adjustment resistor 3131c” ’ , the equivalent resistance of the EH circuit 3131 is adjustable such that the amount of the allocated energy harvested by the EH circuit 3131 is adjustable. That is, the EH of the system is adjustable, so as to achieve the control of an adjustable EH. The adjustment resistor 3131c” ’ is programmable, and can change its resistance according to the input command voltage from the EH control part 3132.

In an embodiment of the present application, the EH circuit 3131 may further comprises a current sensor (not shown) . The current sensor may measure the charging current generated by the voltage regulator 3131b and inform the EH control part 3132 of the measured charging current. Then, the EH control part 3132 may adjust the PWM signal or resistance adjustment voltage according to the measured charging current, so as to realize a closed-loop current control for the EH circuit 3131.

Fig. 8 is a flowchart illustrating a method for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) in an MR damping/braking system according to an embodiment of the present application. As shown in Fig. 8, the method 800 comprises steps S810-S830. The step S810 is to allocate a desired overall damping force/braking torque in the MR damping/braking system into a desired MR damping force/braking torque and a desired EH damping force/braking torque. The step S820 is to generate an allocated MR damping force/braking torque according to the desired MR damping force/braking torque. And, the step S830 is to harvest an allocated energy according to the desired EH damping force/braking torque.

In an embodiment of the present application, the step S830 may comprises: switching on/off the harvesting of the allocated energy or adjusting an amount of the allocated energy, according to the desired EH damping force/braking torque.

In an embodiment of the present application, the desired MR damping force/braking torque is a high level or a low level, and the amount of the allocated energy is non-adjustable and has a high level or a low level. In the circumstances, where the generated MR damping force/braking torque has the high level, the desired EH damping force/braking torque is switched on to have a high level. On the other hand, where the generated MR damping force/braking torque has the low level, the desired EH damping force/braking torque is switched off to have a low level.

In another embodiment of the present application, the desired MR damping force/braking torque is a high level or a low level, and the harvesting of the allocated energy is adjustable. In the circumstances, where the generated MR damping force/braking torque has the high level, the desired EH damping force/braking torque is allocated at its maximum level. On the other hand, where the generated MR damping force/braking torque has the low level, the desired EH damping force/braking torque is allocated at its minimum level.

Fig. 9 is a flowchart illustrating the step S810 according to an embodiment of the present application. In the embodiment, the generated MR damping force/braking torque is adjustable. In the circumstances, the step S810 may comprise sub-steps S811 and S812, as shown in Fig. 9. The sub-step S811 is to compare the desired overall damping force/braking torque with a sum of an EH force/torque corresponding to a maximum amount of the allocated energy harvested by the EH circuit and an MR viscous damping force/braking torque. And, the sub-step S812 is to generate the desired MR damping force/braking torque and the desired EH damping force/braking torque based on a result of the comparison.

In an example of the present application, the amount of the allocated energy is non-adjustable and has a high level or a low level. In the circumstances, on the one hand, where the desired overall damping force/braking torque is less than the sum of the EH and MR viscous force/torque, the desired MR damping force/braking torque is allocated to represent the desired overall damping force/braking torque and the desired EH damping force/braking torque is allocated to its low level. On the other hand, where the desired overall damping force/braking torque is larger than or equal to the sum of the EH and MR viscous force/torque, the desired MR damping force/braking torque is allocated to represent a difference between the desired overall damping force/braking torque and the EH force/torque and the desired EH damping force/braking torque is allocated to its high level.

In another example of the present application, the harvesting of the allocated energy is adjustable. In the circumstances, on the one hand, where the desired overall damping force/braking torque is less than the sum of the EH and MR viscous force/torque, the desired MR damping force/braking torque is allocated to represent zero and the desired EH damping force/braking torque is allocated to represent the desired overall damping force/braking torque. On the other hand, where the desired overall damping force/braking torque is larger than or equal to the sum of the EH and MR viscous force/torque, the desired MR damping force/braking torque is allocated to represent a difference between the desired overall damping force/braking torque and the EH force/torque and the desired EH damping force/braking torque is allocated to its maximum.

Fig. 10 illustrates an example of the application to be applied to a vehicle suspension system. For the regenerative MR suspension system 80, a regenerative MR damper 93 (i.e. a linear MR damper integrated with an energy harvesting circuit) is used. The regenerative MR suspension system 80 comprises a spring 92 and a damper 93. The suspension is mounted between the chassis 91 and the wheel 94 of a car. When the wheel 94 is excited under the road disturbance, the spring 92 absorbs the vibratory energy, and then the damper 93 dissipates the vibratory energy. The regenerative MR damper 93 will convert a part of the vibratory energy into electrical energy and output the controllable damping force to the chassis 91, to ensure the ride comfort.

The energy harvesting part of the damper 93 may be a linear electromagnetic power generator, a rotary electromagnetic power generator with transmission conversion, etc. The damper 93 will output the AC power to the energy harvesting circuit 85. For the used energy harvesting circuit 85, it is one type of non-adjustable circuit with an on-off switch, as illustrated in Fig. 5. For the regenerative MR suspension system 80, the adopted MR control method can be the on-off control. This control algorithm is expressed by the following equation (5) .

where

and

are the velocity in the vertical direction of the chassis and wheel of the car, respectively. This conventional control algorithm will output two states F_min/F_max. Therefore, the used control method can be expressed by following equation (6) .

As shown in Fig. 10, the dynamic sensor 95 will measure the dynamic responses of the chassis 91, such as

and

etc. The force dividing unit 97 (divider) will run the control algorithm as expressed in the above equation (6) . The MR damping controller 98 will run the algorithm same as the conventional on-off control, and output the command voltage u_max or 0 to the current driver 83. Then, the current driver 83 will output the driving current to the MR coil within the damper 93. The energy harvesting controller 99 (EH control part) will output the on/off control signal to the switch 84 of the energy harvesting circuit 85. As determined by the conventional on-off control algorithm, when the MR part outputs the maximum voltage, the switch 84 will turn on and the output overall force to the damper 93 is F_{MR_max}+F_EH； when the MR part outputs the minimum voltage 0V, the switch 84 will turn off and the output overall force to the damper 93 is F_{MR_min}. In this way, the vibration control performance, namely ride comfort, can be ensured, firstly. The energy harvesting is selectively functioned. It should be noted that the on-off control used in this example is not the only suitable control algorithm, and many other control algorithms could also be used.

Fig. 11 illustrates another example of the application to be applied to an intelligent prosthetic system. For the intelligent prosthetic system 90, a two-functional MR device 910 (i.e. a rotary MR brake integrated with an energy harvesting circuit) is used as the artificial knee joint. The MR brake 910 is connected with the human thigh 905 and human shank 920. The foot 930 contacts the ground. The MR brake 910 with the energy harvesting function can provide a controlled torque to support the human body and assist the human walking. And, it has an electromagnetic power generator (motor) , and the generator is integrated into the MR brake. The power generator can convert the kinetic energy of knee rotation into the electrical energy, and output the generated AC power to the energy harvesting circuit 911.

For the used energy harvesting circuit 911, it is one type of the impedance-adjustable circuit with a PWM signal controlled switch 931, as illustrated in Fig. 6. Therefore, the adopted control method for the intelligent prosthetic system 90 will be able to provide an adjustable output. For the intelligent prosthetic system 90, its required torque is quite related to the gait states and walking velocities. Therefore, the adopted control method should output continuously controlled braking torque, rather than two simple states τ_min/τ_max.

Firstly, the system controller 935 will determine the desired overall braking torque τ_r, according to the information from the dynamic sensor 934, torque sensor 932, or other sensors. Then, the torque dividing unit 936 (divider) will calculate the viscous braking torque τ_η and maximum energy harvesting torque τ_{EH_max}. For the prosthetic system design, the viscous braking torque τ_η is usually very small and can be neglected. τ_{EH_max} can be calculated from the above equations (2) and (3) . In some intervals of a walking cycle, such as high angular velocity, the desired braking torque is smaller than the torque produced by energy harvesting at the same angular velocity. In this case, the energy harvesting controller 938 (EH control part) can adjust the braking torque of energy harvesting, with no need to turn on MR braking part. Thus, the harvested energy can be maximized while reducing the power consumption of MR coil.

The energy harvesting braking torque control will use the open-loop. To achieve the desired braking torque τ_r, the duty cycle λ of the PWM signal to the switch 931 is calculated by the energy harvesting controller 938 as below.

In some intervals of the walking cycle, such as low angular velocity, the desired braking torque is larger than the torque produced by energy harvesting at the same angular velocity. In this case, both the energy harvesting controller 938 and MR damping controller 937 will work. The energy harvesting part will remain in its maximum ability, that is, λ ＝ 100％. The target MR braking torque τ_rMR will be allocated as τ_r -τ_{EH_max}.

The MR braking torque control will use the open-loop method. The relation between the electrical current and MR braking torque can be calibrated and stored in the MR braking controller 937. As the current is proportional to the command voltage input to the current driver 939, the controller 937 will output the corresponding command voltage.

Although the above descriptions include many specific arrangements and parameters, it should be noted that these specific arrangements and parameters only served to illustrate one embodiment of the present application. This should not be considered as the limitations on the scope of the application. It can be understood by those skilled in the art that various modifications, additions and substitutions may be made thereto without departing from the scope and spirit of the present application. Therefore, the scope of the present application should be construed on the basis of the appended claims.

Claims

A device for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) in an MR damping/braking system, comprising:

a divider configured to generate a first allocating signal and a second allocating signal based on a desired overall damping force/braking torque；

an MR damping/braking controller configured to generate, in response to the first allocating signal, an MR command signal for generating an allocated MR damping force/braking torque； and

an EH controller configured to harvest an allocated energy in response to the second allocating signal.
The device of claim 1, wherein the EH controller comprises:

an EH circuit configured to harvest the allocated energy from a power generator of the MR damping/braking system； and

an EH control part configured to switch on/off the EH circuit or adjust an amount of the allocated energy harvested by the EH circuit, in response to the second allocating signal.
The device of claim 2, wherein the divider generates the first and second allocating signals according to output modes of the MR damping/braking controller and the EH control part.
The device of claim 2, wherein the MR damping/braking controller has a high output or a low output, and the divider generates the first allocating signal according to the desired overall damping force/braking torque, and the second allocating signal according to the high output or the low output of the MR damping/braking controller.
The device of claim 4, wherein

the divider generates the second allocating signal with which the EH control part switches off the EH circuit or adjusts the amount of the allocated energy harvested by the EH circuit to its minimum, where the MR damping/braking controller has the low output； and

the divider generates the second allocating signal with which the EH control part switches on the EH circuit or adjusts the amount of the allocated energy harvested by the EH circuit to its maximum, where the MR damping/braking controller has the high output.
The device of claim 2, wherein an output of the MR damping/braking controller is adjustable, and the divider is further configured to compare the desired overall damping force/braking torque with a sum of an EH force/torque corresponding to a maximum amount of the allocated energy harvested by the EH circuit and an MR viscous damping force/braking torque, and to generate the first and second allocating signals based on a result of the comparison.
The device of claim 6, wherein

the amount of the allocated energy harvested by the EH circuit has a high level or a low level；

the divider generates the first allocating signal to represent the desired overall damping force/braking torque and the second allocating signal with which the EH control part switches off the EH circuit, where the desired overall damping force/braking torque is less than the sum of the EH and MR viscous force/torque； and

the divider generates the first allocating signal to represent a difference between the desired overall damping force/braking torque and the EH force/torque and the second allocating signal with which the EH control part switches on the EH circuit, where the desired overall damping force/braking torque is larger than or equal to the sum of the EH and MR viscous force/torque.
The device of claim 6, wherein

the amount of the allocated energy harvested by the EH circuit is adjustable；

the divider generates the first allocating signal to be zero and the second allocating signal with which the EH control part adjusts the amount of the allocated energy harvested by the EH circuit to correspond to the desired overall damping force/braking torque, where the desired overall damping force/braking torque is less than the sum of the EH and MR viscous force/torque； and

the divider generates the first allocating signal to represent a difference between the desired overall damping force/braking torque and the EH force/torque, and the second allocating signal with which the EH control part adjusts the amount of the allocated energy harvested by the EH circuit to its maximum, where the desired overall damping force/braking torque is larger than or equal to the sum of the EH and MR viscous force/torque.
The device of claim 5 or 7, wherein the EH circuit comprises:

a rectifier configured to rectify an AC voltage from the power generator to a DC voltage；

a voltage regulator configured to generate a charging current proportional to the DC voltage；

a switch configured to connect/disconnect the rectifier with the voltage regulator in response to an on/off signal from the EH control part； and

an energy storage configured to store electrical energy harvested from the charging current.
The device of claim 5 or 8, wherein the EH circuit comprises:

a rectifier configured to rectify an AC voltage from the power generator to a DC voltage；

a voltage regulator configured to generate a charging current proportional to the DC voltage；

a PWM controlled switch connected between the rectifier and the voltage regulator and configured to adjust the charging current in response to a PWM signal with a controlled duty cycle from the EH control part； and

an energy storage configured to store electrical energy harvested from the charging current.
The device of any of claims 5 and 8, wherein the EH circuit comprises:

a rectifier configured to rectify an AC voltage from the power generator to a DC voltage；

a voltage regulator configured to generate a charging current proportional to the DC voltage；

an adjustment resistor connected to the voltage regulator and configured to adjust the charging current by adjusting the resistance of itself in response to a resistance adjustment voltage from the EH control part； and

an energy storage configured to store electrical energy harvested from the charging current.
The device of claim 10 or 11, wherein the EH circuit further comprises a current sensor configured to measure the charging current and inform the EH control part of the measured charging current, and the EH control part is further configured to adjust the PWM signal or resistance adjustment voltage according to the measured charging current.
A method for coordinating magnetorheological (MR) damping/braking and energy harvesting (EH) in an MR damping/braking system, comprising:

allocating a desired overall damping force/braking torque in the MR damping/braking system into a desired MR damping force/braking torque and a desired EH damping force/braking torque；

generating an allocated MR damping force/braking torque according to the desired MR damping force/braking torque； and

harvesting an allocated energy according to the desired EH damping force/braking torque.
The method of claim 13, wherein harvesting an allocated energy according to the desired EH damping force/braking torque comprises:

switching on/off the harvesting of the allocated energy or adjusting an amount of the allocated energy, according to the desired EH damping force/braking torque.
The method of claim 14, wherein the desired MR damping force/braking torque is a high level or a low level, and the amount of the allocated energy is non-adjustable and has a high level or a low level；

the desired EH damping force/braking torque is switched on to have a high level, where the generated MR damping force/braking torque has the high level； and

the desired EH damping force/braking torque is switched off to have a low level, where the generated MR damping force/braking torque has the low level.
The method of claim 14, wherein the desired MR damping force/braking torque is a high level or a low level, and the harvesting of the allocated energy is adjustable；

the desired EH damping force/braking torque is allocated at its maximum level, where the generated MR damping force/braking torque has the high level； and

the desired EH damping force/braking torque is allocated at its minimum level, where the generated MR damping force/braking torque has the low level.
The method of claim 14, wherein the desired MR damping force/braking torque is adjustable between its minimum and maximum states, and allocating a desired overall damping force/braking torque in the MR damping/braking system into a desired MR damping force/braking torque and a desired EH damping force/braking torque comprises:

comparing the desired overall damping force/braking torque with a sum of an EH force/torque corresponding to a maximum amount of the allocated energy and an MR viscous damping force/braking torque； and

generating the desired MR damping force/braking torque and the desired EH damping force/braking torque based on a result of the comparison.
The method of claim 17, wherein

the amount of the allocated energy is non-adjustable and has a high level or a low level；

the desired MR damping force/braking torque is allocated to represent the desired overall damping force/braking torque and the desired EH damping force/braking torque is allocated to its low level, where the desired overall damping force/braking torque is less than the sum of the EH force/torque and the MR viscous damping force/braking torque； and

the desired MR damping force/braking torque is allocated to represent a difference between the desired overall damping force/braking torque and the EH force/torque and the desired EH damping force/braking torque is allocated to its high level, where the desired overall damping force/braking torque is larger than or equal to the sum of the EH force/torque and the MR viscous damping force/braking torque.
The method of claim 17, wherein

the harvesting of the allocated energy is adjustable；

the desired MR damping force/braking torque is allocated to represent zero and the desired EH damping force/braking torque is allocated to represent the desired overall damping force/braking torque, where the desired overall damping force/braking torque is less than the sum of the EH force/torque and the MR viscous damping force/braking torque； and

the desired MR damping force/braking torque is allocated to represent a difference between the desired overall damping force/braking torque and the EH force/torque and the desired EH damping force/braking torque is allocated to its maximum, where the desired overall damping force/braking torque is larger than or equal to the sum of the EH force/torque and the MR viscous damping force/braking torque.