Dielectric elastomer-rope traction force transmission system and method for tail end direct drive force compensation

Abstract

The present invention relates to a dielectric elastomer-rope traction force transmission system and method for tail end direct drive force compensation. The system comprises a PC / control system, a driver, a data collection card, a precision voltage source, a sensing module, a servo electric motor, a force sensor, a dielectric elastomer driver, an anchor point, a Bowden cable and a sleeve, wherein the PC / control system is connected to the data collection card; a lead-out wire of the data collection card is respectively connected to the driver, the force sensor, the precision voltage source and the sensing module; the driver is used for controlling the servo electric motor; one side of the force sensor is connected to the servo electric motor by means of the Bowden cable, and the other side thereof is connected to the dielectric elastomer driver by means of the Bowden cable; the precision voltage source and the sensing module are both connected to a wire in the Bowden cable; and the dielectric elastomer driver is fixed to the anchor point. The dielectric elastomer-rope traction force transmission system for tail end direct drive force compensation provided in the present invention can implement precise force control in a traditional Bowden cable transmission system.

Description

Dielectric elastomer-rope traction transmission system and method for terminal direct drive force compensation Technical Field

[0001] The present invention relates to a circuit for detecting the capacitance of a dielectric elastomer, a dielectric elastomer-rope traction force transmission system for terminal direct drive force compensation, and a method thereof. Background Art

[0002] Powered exoskeletons assist and enhance movement through force transmission in human-machine interaction, showing broad prospects in scenarios such as medical rehabilitation, rescue assistance, and field marches. Among them, joint-anchored exoskeletons are smaller in size, lighter in weight, and less prone to joint dislocation. They have significant advantages in scenarios requiring portability and high endurance. They use a traditional Bowden cable transmission system, in which the traction rope passes through an axially incompressible sleeve to connect the drive end and the anchor point. However, due to the friction in the sleeve, the tension of the traction rope at the drive end and the anchor end is not equal, and the difference is affected by a variety of time-varying factors in the motion state, so the current drive control actually adopts a position control method. Precise force control is an indispensable part of safe human-machine interaction, so it is very necessary to study how to achieve precise and flexible control of the Bowden cable drive system.

[0003] Summary of the Invention

[0004] In order to solve the above technical problems, the present invention proposes a dielectric elastomer-rope traction power transmission system with terminal direct drive force compensation, which can achieve precise force control in the traditional Bowden cable transmission system.

[0005] The technical solution of the present invention to solve the above problems is: a dielectric elastomer-rope traction power transmission system with terminal direct drive force compensation, which is special in that:

[0006] Includes PC / control system, driver, data acquisition module, precision voltage source, sensing module, servo motor, force sensor, dielectric elastomer actuator (DEA), anchor point, Bowden cable and bushing;

[0007] The PC / control system is connected to the data acquisition module, and the lead wires from the data acquisition module are connected to the driver, force sensor, precision voltage source and sensing module respectively;

[0008] The driver is used to control the servo motor; one side of the force sensor is connected to the servo motor through a Bowden cable, and the other side is connected to the dielectric elastomer driver (DEA) through the Bowden cable. The precision voltage source and the sensing module are both connected to the wires in the Bowden cable, and the dielectric elastomer driver (DEA) is fixed to the anchor point.

[0009] Furthermore, the Bowden cable includes, from the inside out, a positive conductor layer, a first insulating layer, a negative conductor layer, a second insulating layer and a braided sleeve.

[0010] Furthermore, the dielectric elastomer actuator (DEA) is a cylindrical dielectric elastomer actuator.

[0011] Furthermore, the output shaft of the servo motor is connected to a reel, and the Bowden cable on one side of the force sensor is wound on the reel.

[0012] Furthermore, the data acquisition module is a data acquisition card (DAQ).

[0013] In addition, the present invention also proposes a compensation method for the dielectric elastomer-rope traction force transmission system based on the above-mentioned terminal direct drive force compensation, which is special in that it includes the following steps:

[0014] 1) At a specific time point, the servo motor is controlled by the PC / control system to apply a certain tension to the Bowden cable in the casing. This tension is calculated by the existing control algorithm based on the human body and is the tension required by the human body to achieve a balanced state or assist walking in this state.

[0015] 2) Real-time measurement of the tension applied to the Bowden cable using a force sensor;

[0016] 3) Since the DEA is connected and fixed to the anchor point, the tension of the Bowden cable is transmitted to the DEA, causing the DEA to deform and send a perception signal to the PC / control system through the sensing module;

[0017] 4) The PC / control system analyzes the data and compares the sensing signal with the servo motor control signal to obtain the tension loss caused by friction of the Bowden cable in the casing;

[0018] 5) The PC / control system applies a control signal to the dielectric elastomer actuator (DEA) through a precision voltage source, causing the dielectric elastomer actuator (DEA) to stretch to reach the initial tension of the motor control signal, thereby achieving rapid force compensation.

[0019] The above-mentioned dielectric elastomer-rope traction power transmission system with terminal direct drive force compensation uses a dielectric elastomer driver, which stands out among a number of soft robots for its high-speed operation, high efficiency, controllability, and ability to generate muscle-like force and strain. However, due to the presence of high-voltage signals, the sensing module needs to use large and expensive electronic components, such as high-voltage power amplifiers and AC transformers, to couple the sinusoidal low-voltage signal with the high-voltage drive signal on the high-voltage side. The sensing module for dielectric elastomer capacitance detection uses existing large-scale professional and expensive electronic equipment, such as peak detectors, to extract the voltage change of the sinusoidal detection signal on the resistor to be measured. The capacitance detection circuit is complex and the cost is relatively high. To solve this problem, the present invention also proposes a sensing module, which includes a circuit for detecting the capacitance of the dielectric elastomer.

[0020] The circuit for detecting the capacitance of a dielectric elastomer includes an amplifier unit, a voltage detection unit, a voltage processing unit, a clamping unit and a high-voltage power supply. The output end of the amplifier unit is connected to the input end of the voltage detection unit, the first output end of the voltage detection unit is connected to the input end of the clamping unit and the first input end of a dielectric elastomer driver (DEA), the second output end of the voltage detection unit is connected to the input end of the voltage processing unit, the output end of the voltage processing unit is connected to a data acquisition module, the output end of the clamping unit is connected to the low-voltage negative pole of the high-voltage power supply, and the second input end of the dielectric elastomer driver (DEA) is connected to the high-voltage positive pole of the high-voltage power supply.

[0021] Furthermore, the above-mentioned amplification unit includes an operational amplifier U1, a resistor R10 and a resistor R11, the positive pole of the operational amplifier U1 is connected to the output end of the single-chip microcomputer, the negative pole of the operational amplifier U1 is connected to one end of the resistor R10 and the resistor R11 respectively, the other end of the resistor R10 is connected to the output end of the operational amplifier U1, and the other end of the resistor R11 is connected to the low-voltage negative pole of the high-voltage power supply.

[0022] Furthermore, the above-mentioned voltage detection unit includes a differential amplifier U2 and a voltage sampling resistor R1, the two ends of the voltage sampling resistor R1 are respectively connected to the positive and negative poles of the differential amplifier U2, the output end of the differential amplifier U2 is connected to the voltage processing unit, the negative pole of the differential amplifier U2 is connected to the clamping unit, and the negative pole of the differential amplifier U2 is connected to the dielectric elastomer.

[0023] Furthermore, the above-mentioned clamping unit includes a Zener diode D1, a Zener diode D2 and a capacitor C1, one end of the capacitor C1 is connected to the cathode of the diode D1, the other end of the capacitor C1 is connected to the low-voltage negative electrode of the high-voltage power supply, the anode of the diode D1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the low-voltage negative electrode of the high-voltage power supply.

[0024] Furthermore, the above-mentioned voltage processing unit includes an operational amplifier U3, a sliding rheostat R3 and a resistor R4, one end of the sliding rheostat R3 is connected to the output end of the voltage detection unit, and the other end is connected to the negative electrode of the operational amplifier U3, the two ends of the resistor R4 are respectively connected to the negative electrode and the output end of the operational amplifier U3, and the positive electrode of the operational amplifier U3 is connected to the low-voltage negative electrode of the high-voltage power supply.

[0025] More preferably, the voltage processing unit also includes a resistor R5, a resistor R6, a capacitor C2 and an operational amplifier U4, one end of the resistor R5 is connected to the output end of the operational amplifier U3, and the other end is connected to one end of the capacitor C2, the other end of the capacitor C2 is connected to the negative electrode of the operational amplifier U4, one end of the resistor R6 is connected to one end of the capacitor C2, and the other end is connected to the positive electrode of the operational amplifier U4.

[0026] More preferably, the voltage processing unit also includes a resistor R7 and a capacitor C3, one end of the capacitor C3 is connected to one end of the resistor R5, and the other end is connected to the output end of the operational amplifier U4, and the two ends of the resistor R7 are respectively connected to the negative electrode and the output end of the operational amplifier U4.

[0027] More preferably, the voltage processing unit also includes a resistor R8 and a resistor R9, the output end of the operational amplifier U4 is connected to one end of the resistor R8 and the resistor R9 respectively, the other end of the resistor R8 is connected to the power signal output end, and the other end of the resistor R9 is connected to the low-voltage negative electrode of the high-voltage power supply. The output end of the operational amplifier U4 is used to output a voltage sampling signal.

[0028] Advantages of the present invention:

[0029] The dielectric elastomer-rope traction force transmission system with terminal direct drive force compensation provided by the present invention measures the tension of the Bowden cable in real time through a force sensor. Under the tension of the Bowden cable, the cylindrical DEA is deformed, and a perception signal is sent to the PC / control system through the perception module. The PC / control system then analyzes the data and compares it with the servo motor control signal to obtain the tension lost by the friction of the Bowden cable in the casing. A control signal is then applied to the cylindrical DEA through a precision voltage source, so that the cylindrical dielectric elastomer driver is stretched to reach the initial tension of the motor control signal, thereby performing rapid force compensation. The circuit design in the perception module of the present invention overcomes the shortcomings of the prior art, realizes the detection of the dielectric elastomer capacitance from the low-voltage end, avoids professional high-voltage detection equipment, has a simple and reliable circuit structure, and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 is a schematic diagram of a dielectric elastomer-rope traction force transmission system with terminal direct drive force compensation;

[0031] FIG2 is a working principle diagram of the dielectric elastomer-rope traction transmission system for terminal direct drive force compensation;

[0032] FIG3 is a control principle diagram of a dielectric elastomer-rope traction force transmission system with terminal direct drive force compensation;

[0033] FIG4 is a functional block diagram of a circuit for detecting capacitance of a dielectric elastomer;

[0034] FIG5 is a circuit diagram for detecting the capacitance of a dielectric elastomer;

[0035] FIG6 is a diagram showing the working principle of detecting the capacitance of a dielectric elastomer. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention for which protection is claimed, but merely represents selected embodiments of the present invention.

[0037] Referring to Figures 1 to 3, a dielectric elastomer-rope traction transmission system with end-direct drive force compensation includes a PC / control system, a driver, a data acquisition module, a precision voltage source, a sensing module, a servo motor, a force sensor, a dielectric elastomer actuator (DEA), an anchor point, a Bowden cable, and a sleeve.

[0038] The PC / control system is connected to the data acquisition module, and the lead wires from the data acquisition module are connected to the driver, force sensor, precision voltage source and sensing module respectively;

[0039] The driver is used to control the servo motor; one side of the force sensor is connected to the servo motor through a Bowden cable, and the other side is connected to the dielectric elastomer driver (DEA) through the Bowden cable. The precision voltage source and the sensing module are both connected to the wires in the Bowden cable, and the dielectric elastomer driver (DEA) is fixed to the anchor point.

[0040] As a preferred embodiment of the present invention, the Bowden cable includes a positive conductor layer, a first insulating layer, a negative conductor layer, a second insulating layer and a braided sleeve from the inside to the outside, and the precision voltage source and the sensing module are both connected to the positive conductor layer and the negative conductor layer in the Bowden cable.

[0041] As a preferred embodiment of the present invention, the dielectric elastomer actuator (DEA) can be any dielectric elastomer actuator that can generate axial deformation by applying an electric field, preferably a cylindrical dielectric elastomer actuator, because the deformation of the cylindrical dielectric elastomer is more uniform, and the perception and control are more accurate.

[0042] As a preferred embodiment of the present invention, the output shaft of the servo motor is connected to a reel, and the Bowden cable on one side of the force sensor is wound on the reel. The output shaft of the servo motor drives the reel to rotate, and the rotation of the reel winds the Bowden cable.

[0043] As a preferred embodiment of the present invention, the data acquisition module is a data acquisition card (DAQ). The data acquisition card (DAQ) automatically collects non-electrical or electrical signals from the driver, precision voltage source, sensing module, and force sensor, and sends them to a PC / control system for analysis and processing.

[0044] As a preferred embodiment of the present invention, the sensing module includes a circuit for detecting the capacitance of the dielectric elastomer.

[0045] As shown in Figure 4, the circuit for detecting the capacitance of the dielectric elastomer includes an amplifying unit, a voltage detecting unit, a voltage processing unit, a clamping unit and a high-voltage power supply. The input end of the amplifying unit is connected to the output end of the PC / control system, the output end of the amplifying unit is connected to the input end of the voltage detecting unit, the first output end of the voltage detecting unit is connected to the input end of the clamping unit and the first input end of the dielectric elastomer, the second output end of the voltage detecting unit is connected to the input end of the voltage processing unit, the output end of the voltage processing unit is connected to the input end of the PC / control system through a data acquisition module, the output end of the clamping unit is connected to the low-voltage negative pole of the high-voltage power supply, and the second input end of the dielectric elastomer is connected to the high-voltage positive pole of the high-voltage power supply.

[0046] FIG5 shows a schematic diagram of a circuit connection for detecting the capacitance of a dielectric elastomer. For ease of illustration, only the portion relevant to this embodiment is shown, which is described in detail as follows:

[0047] The amplification unit includes an operational amplifier U1, a resistor R10 and a resistor R11. The positive electrode of the operational amplifier U1 is connected to the output end of the PC / control system, the negative electrode of the operational amplifier U1 is connected to one end of the resistor R10 and the resistor R11 respectively, the other end of the resistor R10 is connected to the output end of the operational amplifier U1, and the other end of the resistor R11 is connected to the low-voltage negative electrode of the high-voltage power supply.

[0048] The voltage detection unit includes a differential amplifier U2 and a voltage sampling resistor R1. The voltage sampling resistor R1 is used to perform voltage division sampling on the dielectric elastomer. The two ends of the voltage sampling resistor R1 are respectively connected to the positive and negative electrodes of the differential amplifier U2. The output end of the differential amplifier U2 is connected to the voltage processing unit. The negative electrode of the differential amplifier U2 is connected to the clamping unit. The negative electrode of the differential amplifier U2 is connected to the dielectric elastomer.

[0049] The clamping unit includes a Zener diode D1, a Zener diode D2 and a capacitor C1, one end of the capacitor C1 is connected to the cathode of the diode D1, the other end of the capacitor C1 is connected to the low-voltage cathode of the high-voltage power supply, the anode of the diode D1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the low-voltage cathode of the high-voltage power supply.

[0050] The voltage processing unit includes an operational amplifier U3, a sliding rheostat R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C2, an operational amplifier U4, a resistor R7, a capacitor C3, a resistor R8, and a resistor R9. One end of the sliding rheostat R3 is connected to the output end of the voltage detection unit and the other end is connected to the negative electrode of the operational amplifier U3. The two ends of the resistor R4 are respectively connected to the negative electrode and the output end of the operational amplifier U3. The positive electrode of the operational amplifier U3 is connected to the low-voltage negative electrode of the high-voltage power supply. One end of the resistor R5 is connected to the output end of the operational amplifier U3 and the other end is connected to one end of the capacitor C2. The other end of the capacitor C2 is connected to the negative electrode of the operational amplifier U4. One end of the resistor R6 is connected to one end of the capacitor C2 and the other end is connected to the positive electrode of the operational amplifier U4. One end of the capacitor C3 is connected to one end of the resistor R5 and the other end is connected to the output end of the operational amplifier U4. The two ends of the resistor R7 are respectively connected to the negative electrode and the output end of the operational amplifier U4. The output of operational amplifier U4 is connected to one end of resistors R8 and R9, respectively. The other end of resistor R8 is connected to one of the power signal outputs (i.e., terminal V4) of the PC / control system. The other end of resistor R9 is connected to the low-voltage negative terminal of the high-voltage power supply. The output of operational amplifier U4 is connected to the input of the PC / control system via a data acquisition module. The voltage at terminal V4 is 2.5V. The output of the PC / control system is used to transmit a square wave signal and receive the voltage signal output by the capacitance detection circuit.

[0051] The circuit for detecting the capacitance of a dielectric elastomer operates as follows:

[0052] The high-voltage power supply VH provides driving power for the dielectric elastomer. Depending on the dielectric elastomer, the voltage of this high-voltage power supply VH can range from 3000V to 5000V, or even higher. The low-voltage signal detection power supply VL provides the detection signal for the capacitance detection circuit. This low-voltage signal detection power supply outputs a 1V, 1kHz sinusoidal signal. The operating principle is shown in Figure 6. When high voltage is applied to the electrodes at both ends of the dielectric elastomer, the dielectric elastomer is compressed and deformed, and the capacitance changes. The capacitance value is measured using the low-voltage detection signal.

[0053] The circuit is provided with an operational amplifier U1, a differential amplifier U2, an operational amplifier U3, an operational amplifier U4, a voltage-stabilizing diode D1, a voltage-stabilizing diode D2, and a sliding resistor R3. Other devices in the circuit are resistor-capacitor elements.

[0054] The detection signal generated by the single-chip microcomputer is amplified by the operational amplifier U1 and then connected to one end of the resistor to be measured R1. The voltage signal of the resistor to be measured is then measured by the differential amplifier U2. The voltage is then processed by the voltage processing unit and connected to the input end of the single-chip microcomputer. The voltage signal is then calculated and converted by the single-chip microcomputer to obtain the capacitance of the dielectric elastomer to be measured.

[0055] The specific calculation process is as follows: Kirchhoff's voltage law can be obtained:

[0056] Given the amplitude and phase of the low-voltage detection signal VL output by the microcontroller, perform phase detection on the voltage signal received at the microcontroller input to obtain its amplitude and phase. According to the cosine formula, we can get:

[0057] Where θ is the angle between V1 and V3.

[0058] Where ξ is the angle between V2 and V3.

[0059] The AC voltage and current flowing through the resistor are in phase, and the AC current flowing through the capacitor leads the voltage by 90°. Then:

[0060] Where χ is the angle between I1 and I2.

[0061] According to Kirchhoff's current law: I2=V22πfC1

[0062] According to the cosine formula, we can get:

[0063] According to the impedance theorem, we can get:

[0064] Where Z is the impedance of the dielectric elastomer, Rs is the equivalent resistance of the dielectric elastomer, and Ca is the equivalent capacitance of the dielectric elastomer.

[0065] In addition, the present invention also proposes a compensation method for the dielectric elastomer-rope traction force transmission system based on the above-mentioned terminal direct drive force compensation, referring to Figures 1-3, comprising the following steps:

[0066] 1) At a specific time point, the servo motor is controlled by the PC / control system to apply a certain tension to the Bowden cable in the casing. This tension is calculated by the existing control algorithm based on the human body and is the tension required by the human body to achieve a balanced state or assist walking in this state.

[0067] 2) The tension on the Bowden cable is measured in real time by a force sensor. The data acquisition module obtains the force signal from the force sensor and transmits it to the PC / control system.

[0068] 3) Since the dielectric elastomer actuator (DEA) is connected and fixed to the anchor point, the tension of the Bowden cable is transmitted to the dielectric elastomer actuator (DEA), causing the dielectric elastomer actuator (DEA) to deform. The data acquisition module obtains the perception signal sent by the perception module and transmits it to the PC / control system;

[0069] 4) The PC / control system analyzes the data and compares the sensing signal with the servo motor control signal to obtain the tension loss caused by friction of the Bowden cable in the casing;

[0070] 5) The PC / control system applies a control signal to the dielectric elastomer actuator (DEA) through the data acquisition module and the precision voltage source, so that the dielectric elastomer actuator (DEA) stretches to reach the initial tension of the motor control signal, realizing rapid force compensation.

[0071] Powered exoskeletons achieve motion assistance and enhancement through force transmission in human-machine interaction. The exoskeleton uses a traditional Bowden cable transmission system, where a traction cable passes through an axially incompressible sleeve to connect the drive end and the anchor point. The dielectric elastomer-rope traction transmission system with terminal direct drive force compensation provided by the present invention can be applied to powered exoskeletons. Its working principle is as follows:

[0072] When a person walks while wearing a lower-limb exoskeleton, the PC / control system controls the servo motor at a specific time point, causing it to apply a certain tension to the Bowden cable inside the exoskeleton casing. This tension is calculated based on the existing control algorithm and is the tension required by the human body to achieve balance or assist walking in this state. The tension of the Bowden cable is measured in real time by a force sensor. Since the cylindrical dielectric elastomer actuator (DEA) is connected and fixed to the anchor point, the tension of the Bowden cable will be transmitted to the cylindrical dielectric elastomer actuator (DEA), causing the cylindrical dielectric elastomer actuator (DEA) to deform. A perception signal is sent to the PC / control system through the sensing module, and the PC / control system analyzes the data. After comparing it with the servo motor control signal, the tension lost by the friction of the Bowden cable in the sleeve can be obtained. Then, a control signal is applied to the cylindrical dielectric elastomer actuator (DEA) through a precision voltage source, causing the cylindrical dielectric elastomer actuator to stretch and reach the initial tension of the motor control signal, performing rapid force compensation, and ultimately achieving precise and flexible control of the Bowden cable drive system.

[0073] The above descriptions are merely embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied to other related system fields, are also included in the scope of protection of the present invention.

Claims

1. A circuit for detecting the capacitance of a dielectric elastomer, characterized in that: It includes an amplifying unit, a voltage detecting unit, a voltage processing unit, a clamping unit and a high-voltage power supply. The output end of the amplifying unit is connected to the input end of the voltage detecting unit, the first output end of the voltage detecting unit is connected to the input end of the clamping unit and the first input end of the dielectric elastomer, the second output end of the voltage detecting unit is connected to the input end of the voltage processing unit, the output end of the voltage processing unit is used to output a signal, the output end of the clamping unit is connected to the low-voltage negative electrode of the high-voltage power supply, and the second input end of the dielectric elastomer is connected to the high-voltage positive electrode of the high-voltage power supply.

2. The circuit for detecting the capacitance of a dielectric elastomer according to claim 1, characterized in that: The amplification unit includes an operational amplifier U1, a resistor R10 and a resistor R11, the positive electrode of the operational amplifier U1 is connected to the output end of the single-chip microcomputer, the negative electrode of the operational amplifier U1 is connected to one end of the resistor R10 and the resistor R11 respectively, the other end of the resistor R10 is connected to the output end of the operational amplifier U1, and the other end of the resistor R11 is connected to the low-voltage negative electrode of the high-voltage power supply.

3. The circuit for detecting the capacitance of a dielectric elastomer according to claim 1, characterized in that: The voltage detection unit includes a differential amplifier U2 and a voltage sampling resistor R1, wherein both ends of the voltage sampling resistor R1 are respectively connected to the positive and negative electrodes of the differential amplifier U2, the output end of the differential amplifier U2 is connected to the voltage processing unit, the negative electrode of the differential amplifier U2 is connected to the clamping unit, and the negative electrode of the differential amplifier U2 is connected to the dielectric elastomer.

4. The circuit for detecting the capacitance of a dielectric elastomer according to claim 1, characterized in that: The clamping unit includes a Zener diode D1, a Zener diode D2 and a capacitor C1, one end of the capacitor C1 is connected to the cathode of the diode D1, the other end of the capacitor C1 is connected to the low-voltage cathode of the high-voltage power supply, the anode of the diode D1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the low-voltage cathode of the high-voltage power supply.

5. The circuit for detecting the capacitance of a dielectric elastomer according to claim 1, characterized in that: The voltage processing unit includes an operational amplifier U3, a sliding rheostat R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C2, an operational amplifier U4, a resistor R7, a capacitor C3, a resistor R8 and a resistor R9; One end of the sliding rheostat R3 is connected to the output end of the voltage detection unit, and the other end is connected to the negative electrode of the operational amplifier U3. The two ends of the resistor R4 are respectively connected to the negative electrode and the output end of the operational amplifier U3, and the positive electrode of the operational amplifier U3 is connected to the low-voltage negative electrode of the high-voltage power supply; one end of the resistor R5 is connected to the output end of the operational amplifier U3, and the other end is connected to one end of the capacitor C2, and the other end of the capacitor C2 is connected to the negative electrode of the operational amplifier U4; one end of the resistor R6 is connected to one end of the capacitor C2, and the other end is connected to the positive electrode of the operational amplifier U4; One end of the capacitor C3 is connected to one end of the resistor R5, and the other end is connected to the output end of the operational amplifier U4. Both ends of the resistor R7 are connected to the negative electrode and the output end of the operational amplifier U4 respectively. The output end of the operational amplifier U4 is connected to one end of the resistor R8 and the resistor R9 respectively. The other end of the resistor R8 is connected to the power signal output end, and the other end of the resistor R9 is connected to the low voltage negative electrode of the high voltage power supply. The output terminal of the amplifier U4 outputs a voltage signal.

6. A dielectric elastomer-rope traction force transmission system with terminal direct drive force compensation, characterized in that: Includes PC / control system, driver, data acquisition module, precision voltage source, sensing module, servo motor, force sensor, dielectric elastomer driver, anchor point, Bowden cable and bushing; The PC / control system is connected to the data acquisition module, and the lead wires from the data acquisition module are respectively connected to the driver, the force sensor, the precision voltage source and the sensing module; The sensing module comprises a circuit for detecting the capacitance of a dielectric elastomer as described in any one of claims 1 to 5; The driver is used to control the servo motor; one side of the force sensor is connected to the servo motor through a Bowden cable, and the other side is connected to the dielectric elastomer driver through the Bowden cable. The precision voltage source and the sensing module are both connected to the wire in the Bowden cable, and the dielectric elastomer driver is fixed to the anchor point.

7. The dielectric elastomer-rope traction force transmission system with terminal direct drive force compensation according to claim 6 is characterized in that: The Bowden cable comprises, from inside to outside, a positive conductor layer, a first insulating layer, a negative conductor layer, a second insulating layer and a braided sleeve.

8. The dielectric elastomer-rope traction force transmission system with terminal direct drive force compensation according to claim 7 is characterized in that: The output shaft of the servo motor is connected to a reel, and the Bowden cable on one side of the force sensor is wound on the reel; 9. The dielectric elastomer-rope traction force transmission system with terminal direct drive force compensation according to claim 6, characterized in that: The dielectric elastomer driver is a cylindrical dielectric elastomer driver; the data acquisition module is a data acquisition card DAQ.

10. A compensation method for a dielectric elastomer-rope traction force transmission system with terminal direct drive force compensation, characterized in that: 1) The servo motor is controlled through the PC / control system to apply a certain tension to the Bowden cable in the exoskeleton casing; 2) Real-time measurement of the tension received by the Bowden cable through a force sensor; 3) The tension of the Bowden cable is transmitted to the dielectric elastomer driver, causing the dielectric elastomer driver to deform and send a perception signal to the PC / control system through the perception module; 4) The PC / control system analyzes the data and compares the sensing signal with the servo motor control signal to obtain the tension loss of the Bowden cable due to friction in the casing; 5) The PC / control system applies a control signal to the dielectric elastomer driver through a precision voltage source, so that the dielectric elastomer driver stretches to reach the initial tension of the motor control signal, thereby achieving rapid force compensation.

Images