Terrain self-adaption method and system for quadruped robot

Abstract

The invention discloses a terrain self-adaption method and system for a quadruped robot, the method and system are applied to a pneumatic driving quadruped flexible robot, and the method comprises the following steps: S1, collecting pressure data of the robot in real time, and performing feature extraction from the pressure data, the feature extraction at least comprises the step of calculating the average pressure, the pressure standard deviation and the pressure difference feature value of the pressure data; s2, judging a current terrain type through a decision tree algorithm according to a feature extraction result, and presetting target air pressure required for the robot to pass through the current terrain; s3, the current actual air pressure of the robot is obtained, and the air pressure error is calculated according to the target air pressure and the actual air pressure; and S4, according to the air pressure error and the actual air pressure fed back in real time, calculating the air pressure adjustment amount by using a PI algorithm. And S5, whether the air pressure adjustment amount is larger than zero or not is judged, if yes, the step S3 is executed again, and if not, the robot keeps running. The air pressure of the pneumatic driving robot is adjusted according to the change of terrains, and it is ensured that the quadruped robot can adapt to different terrains.

Description

Technical Field

[0001] The present invention relates to the field of robot technology, and in particular to a method and system for a quadruped robot to adapt to terrain. Background Art

[0002] Soft robots have become an important part of the robotics field because of their easy manufacturing, low cost, large deformation, and ability to adapt to a variety of complex environments.

[0003] Traditional quadruped robots have limitations in terrain adaptability because they usually rely on rigid structures and fixed gait adjustments and cannot adjust their gait in real time according to the environment like flexible robots.

[0004] In addition, traditional pneumatic soft robots usually adopt open-loop control strategies and lack sensor feedback to adjust their motion posture, which limits their operating efficiency and stability in complex environments. Summary of the invention

[0005] In a first aspect of the present invention, in order to solve the above technical problems, the present invention provides a method for a quadruped robot to adapt to terrain, which is applied to a pneumatically driven quadruped flexible robot, and the method comprises the following steps: S1. Collecting pressure data of the robot in real time, and extracting features from the pressure data, wherein the feature extraction at least includes calculating the average pressure, pressure standard deviation, and pressure difference characteristic value of the pressure data; S2. Determine the current terrain type through a decision tree algorithm according to the result of the feature extraction, and preset the target air pressure required for the robot to pass through the current terrain; S3, obtaining the current actual air pressure of the robot, and calculating the air pressure error according to the target air pressure and the actual air pressure; S4, calculating the air pressure adjustment amount by using a PI algorithm according to the air pressure error and the actual air pressure fed back in real time; S5. Determine whether the air pressure adjustment amount is greater than zero. If so, return to step S3; if not, the robot keeps running.

[0006] Furthermore, the S1 also includes performing data filtering processing on the pressure data, which satisfies the calculation formula:

[0007] in, For time point The filtered value of is the number of pressure data, is the original pressure data.

[0008] Furthermore, the calculating of the average pressure, the pressure standard deviation and the pressure difference characteristic value of the pressure data specifically includes: The average pressure is recorded as , which satisfies the calculation formula:

[0009] in, , , , are the pressures on the robot’s four legs, respectively; The pressure standard deviation is recorded as , which satisfies the calculation formula:

[0010] The pressure difference characteristic value is recorded as , which satisfies the calculation formula: .

[0011] Furthermore, the terrain types include flat land, slightly concave land, severely concave land, slightly protruding land and severely protruding land.

[0012] Furthermore, the air pressure adjustment amount is calculated using the PI algorithm, which satisfies the calculation formula:

[0013] in, is the air pressure adjustment amount, is the proportional gain, is the error between the current actual air pressure and the target air pressure, is the integral gain, From the initial time to the current time The error integral of .

[0014] A second aspect of the present invention provides a system for a quadruped robot to adapt to terrain, comprising a robot body, wherein the robot body comprises: Actuator module; Communication module; A driving module, comprising an air valve and an optocoupler driving circuit, wherein the optocoupler driving circuit is electrically connected to the air valve to drive the opening and closing of the air valve; a sensor module, comprising a thin film pressure sensor and an air pressure sensor, wherein the thin film pressure sensor is arranged at the free end of the actuator module, and the air pressure sensor is arranged at the air valve; and The control module includes a microcontroller and a host computer. The microcontroller is in communication connection with the host computer and controls the switch signal quantity of the gas valve according to the received motion signal of the actuator module.

[0015] Further, the actuator module includes a first actuator, a second actuator, a third actuator and a fourth actuator, wherein: The free ends of the first actuator, the second actuator, the third actuator and the fourth actuator contacting the ground have a rounded structure; Ends of the first actuator, the second actuator, the third actuator and the fourth actuator away from the free end are sequentially surrounded and fixed to the circumferential side wall of the middle piece by fixing pieces.

[0016] Further, the first actuator, the second actuator, the third actuator and the fourth actuator are all provided with: An air bag and an air hole are connected to each other, and the air hole is connected to the air valve; A constraint layer, wherein the constraint layer wraps the airbag and the air hole, and the air hole is ventilated so that the airbag expands and drives the constraint layer to deform, causing the corresponding actuator module to move.

[0017] Furthermore, the first actuator, the second actuator, the third actuator and the fourth actuator are all wrinkle-free pneumatic soft actuators.

[0018] Furthermore, the model of the microcontroller is STM32F407ZET6.

[0019] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: In order to better adapt to the terrain, the present invention adopts feature extraction and decision tree classification to judge the terrain recognition, outputs the target air pressure, ventilation time and ventilation volume according to the classification result of terrain recognition, and adjusts the air pressure of the pneumatic drive robot according to the change of terrain to ensure that the quadruped robot can adapt to different terrains. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A flowchart of a quadruped robot adaptive to terrain disclosed in an embodiment of the present invention; Figure 2 A schematic diagram of the overall structure of a quadruped robot disclosed in an embodiment of the present invention; Figure 3 A schematic diagram of a partial structure of an actuator module disclosed in an embodiment of the present invention; Figure 4 A schematic diagram of a partial structure of a fixing member disclosed in an embodiment of the present invention; Figure 5 A schematic diagram of a partial structure of the middleware disclosed in an embodiment of the present invention; Figure 6 A schematic diagram of a walking state disclosed in an embodiment of the present invention; Figure 7 This is a schematic diagram of the steering state disclosed in an embodiment of the present invention.

[0022] In the figure: 100. Robot body; 111, a first actuator; 112, a second actuator; 113, a third actuator; 114, a fourth actuator; 120, constraint layer; 130, air hole; 140, air bag; 150, thin film pressure sensor; 160, fixing member; 161, first threaded hole; 162, tracheal vent hole; 163, arched fixing block; 170. Intermediate piece; 171. Second threaded hole. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme 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 only 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 creative work are within the scope of protection of the present invention.

[0024] The present invention aims to provide a method and system for a quadruped robot to adapt to terrain, so as to improve the operating efficiency and stability of a pneumatically driven quadruped flexible robot in a complex environment.

[0025] The following is a description of the system for the quadruped robot to adapt to terrain.

[0026] The system of the quadruped robot adaptive terrain includes a robot body 100, and the robot body 100 includes an actuator module, a communication module, a driving module, a sensor module, and a control module.

[0027] First, the actuator module disclosed in this embodiment is described.

[0028] See also Figure 2The actuator module includes a first actuator 111, a second actuator 112, a third actuator 113 and a fourth actuator 114. The ends of the first actuator 111, the second actuator 112, the third actuator 113 and the fourth actuator 114 away from the free end are fixed to the circumferential side wall of the middle member 170 by the fixing member 160 in sequence.

[0029] The first actuator 111 , the second actuator 112 , the third actuator 113 , and the fourth actuator 114 are all wrinkle-free pneumatic soft actuators.

[0030] See also Figure 3 The first actuator 111 , the second actuator 112 , the third actuator 113 and the fourth actuator 114 are all provided with air holes 130 , air bags 140 and a constraint layer 120 . The constraint layer wraps the air bags 140 and the air holes 130 .

[0031] The airbag 140 is communicated with the air hole 130 , and the air hole 130 is communicated with the air valve. The air hole 130 is ventilated so that the airbag 140 expands and drives the constraint layer 120 to deform, causing the corresponding actuator module to move.

[0032] In order to sense different terrains, thin film pressure sensors 150 are provided at the free ends of the first actuator 111 , the second actuator 112 , the third actuator 113 and the fourth actuator 114 in this embodiment that are in contact with the ground.

[0033] In order to make the actuator module more adaptable to walking gait, the free ends of the first actuator 111, the second actuator 112, the third actuator 113 and the fourth actuator 114 in this embodiment that contact the ground are designed to have rounded corners. Preferably, the rounded corner radius is about 1 mm.

[0034] See also Figure 4-5 A second threaded hole 171 is provided on the circumferential side wall of the intermediate piece 170 .

[0035] The fixing member 160 includes a first threaded hole 161 , an air pipe vent hole 162 and an arched fixing block 163 .

[0036] The tracheal vent hole 162 is connected to the air hole 130 .

[0037] The arched fixing block 163 is in close contact with the end surface of the actuator module, and the actuator module is fixed to the circumferential side wall of the middle piece 170 through the first threaded hole 161 and the second threaded hole 171 matched therewith and screws.

[0038] Next, the sensor module disclosed in this embodiment will be described.

[0039] The sensor module includes a thin film pressure sensor 150 , an air pressure sensor, a position sensor, and the like.

[0040] During the initial operation, the topography is read by the thin film pressure sensor 150 and the target air pressure is preset according to the topography.

[0041] The thin film pressure sensor 150 can detect the ground conditions in real time and use the feedback mechanism of the sensor module to adjust the gait and driving parameters of the robot body to improve the movement speed and efficiency.

[0042] The air pressure sensor is set on the air valve to feedback the intake volume, thereby controlling the intake time and controlling the expansion and bending degree of the actuator module. For example, by controlling the inflation time, the situation of the actuator module expanding too much or too little can be solved.

[0043] In one embodiment, in order to prevent the actuator module from being unable to release air, a release solenoid valve may be added to release the air pressure that cannot be released by the actuator module through the release solenoid valve.

[0044] Furthermore, the driving module and the control module disclosed in this embodiment are described.

[0045] The control module includes a microcontroller and a host computer. The microcontroller and the host computer are connected in communication and control the switch signal quantity of the gas valve according to the received motion signal of the actuator module.

[0046] Among them, the microcontroller mainly undertakes three tasks: first, communicate with the host computer through the serial port, receive instructions and return data; second, output control signals to drive the optocoupler circuit to realize the opening and closing of the gas valve; third, use the ADC module to collect the analog quantity of the sensor module to complete the real-time monitoring of the actuator module status.

[0047] Preferably, the model of the microcontroller is STM32F407ZET6.

[0048] The driving module includes an air valve and an optocoupler driving circuit, and the optocoupler driving circuit is electrically connected to the air valve to drive the opening and closing of the air valve.

[0049] This embodiment focuses on realizing the on-off management of the gas valve through optical path coupling technology, and combines the powerful processing capability and peripheral circuit design of the microcontroller STM32 to ensure the stability and scalability of the system.

[0050] Through the coordinated action of the optocoupler drive circuit, ADC sampling circuit, serial communication module, power management module and other auxiliary circuits, precise control and status feedback of the pneumatic actuator can be achieved.

[0051] The communication between the microcontroller and the host computer is completed through the UART interface, and the serial port to USB module is combined to realize the connection with the PC or other control devices, ensuring the reliable transmission of control instructions and data.

[0052] In the optocoupler drive circuit, the output of each optocoupler is connected to the gate of a MOSFET, while the source of the MOSFET is grounded, and the drain is connected to the power supply through the gas valve. When the optocoupler output is turned on, the MOSFET is triggered to enter the on state, thereby providing a power path for the gas valve and completing the opening action of the gas valve. Conversely, when the optocoupler is turned off, the MOSFET is turned off, and the gas valve is powered off and closed. The isolation of the control signal through the optocoupler not only protects the microcontroller from interference on the high-voltage side, but also improves the safety of the system.

[0053] In order to ensure the stability and reliability of the circuit, the peripheral circuits of the optocoupler and MOSFET are also optimized in the design. A resistor is connected in series to each optocoupler input to limit the current and protect the LED from being overdriven; at the same time, a pull-down resistor is connected to the output of the optocoupler to prevent the output signal from being unstable when floating. The gate of the MOSFET is connected to a pull-up resistor to ensure that it remains in the closed state when it is not controlled. In addition, since the gas valve has a certain inductance, reverse electromotive force may be generated during the on-off process. For this reason, a freewheeling diode is connected in parallel at both ends of the MOSFET to absorb the reverse voltage and protect the MOSFET from overvoltage damage.

[0054] The ADC module in the hardware system is responsible for collecting analog signals from sensors, which is used to monitor the foot pressure of the quadruped robot in real time.

[0055] This embodiment designs four ADC channels, and each channel is configured with a corresponding sensor interface and signal conditioning circuit.

[0056] This embodiment uses an external power supply to meet the power requirements of different modules through multi-stage filtering circuits and voltage stabilizers. For microcontrollers and other low-power devices, the circuit provides a 3.3V regulated power supply; and for the high-power parts that drive optocouplers and MOSFETs, a 5V power supply is used. A combination of inductors and capacitors is used in the filtering circuit to form an LC filter, which effectively suppresses power supply noise and ensures the stability of power supply. In addition, in order to prevent transient voltages from impacting the circuit, TVS tubes or varistors are also introduced in the design to absorb surge voltages.

[0057] This embodiment is also designed with a crystal oscillator circuit and a reset circuit. The crystal oscillator circuit provides a clock signal for the microcontroller to ensure the synchronization of its internal processing logic. The reset circuit is composed of a pull-up resistor and a reset button. The user can manually trigger the reset signal, or the reset chip that monitors the power supply voltage can automatically generate a reset signal to ensure that the system can quickly recover in an abnormal state.

[0058] The system uses a microcontroller as the core control module to coordinate the collaboration between various modules; the optocoupler drive circuit ensures the rapid response and isolation protection of the gas valve action; the ADC sampling module provides accurate feedback on the status of the actuator module.

[0059] The microcontroller contains a program for controlling the robot's motion. In order to better adapt to the terrain, this embodiment adds feature extraction and decision tree classification to determine terrain recognition.

[0060] The following is an explanation of the method for the quadruped robot to adapt to terrain.

[0061] See also Figure 1 ,The method of quadruped robot adaptive terrain mainly includes the following steps: S1. Collect the robot's pressure data in real time and extract features from the pressure data.

[0062] The feature extraction includes at least calculating the average pressure, the pressure standard deviation and the pressure difference characteristic value of the pressure data.

[0063] First, the collected pressure data is filtered to satisfy the calculation formula:

[0064] in, For time point The filtered value of is the number of pressure data, is the original pressure data.

[0065] The average pressure is , which satisfies the calculation formula:

[0066] in, , , , are the pressures on the robot’s four legs, respectively; The standard deviation of pressure is , which satisfies the calculation formula:

[0067] The pressure difference characteristic value is , which satisfies the calculation formula: .

[0068] S2. Determine the current terrain type through a decision tree algorithm based on the result of feature extraction, and preset the target air pressure required for the robot to pass through the current terrain.

[0069] Among them, the decision tree divides the terrain types into flat land, slight depression, severe depression, slight protrusion and severe protrusion according to the terrain characteristics.

[0070] Initialize the system parameters and set the target air pressure to be achieved for different terrain features.

[0071] After many experiments, we obtained the most suitable air pressure range and ventilation duration for exercise on flat ground, sandy ground and slopes, calibrated each pressure sensor, and set the initial gait and terrain.

[0072] During the initial operation, the terrain features are read through a thin film pressure sensor, and other parameters such as the target are preset based on the terrain features.

[0073] S3. Obtain the current actual air pressure of the robot, and calculate the air pressure error based on the target air pressure and the actual air pressure.

[0074] S4. Calculate the air pressure adjustment amount using the PI algorithm based on the air pressure error and the actual air pressure fed back in real time.

[0075] The air pressure adjustment is calculated using the PI algorithm, which satisfies the calculation formula:

[0076] in, is the air pressure adjustment amount, is the proportional gain, is the error between the current actual air pressure and the target air pressure, is the integral gain, From the initial time to the current time The error integral of .

[0077] S5. Determine whether the air pressure adjustment amount is greater than zero. If so, return to step S3; if not, the robot keeps running.

[0078] The amount of adjustment of ventilation time is determined by the amount of air pressure adjustment, and the air pressure value is fed back in real time to continue calculating the amount of adjustment of ventilation time. If the air pressure meets the standard, the current air pressure is maintained. If not, the air pressure error is recalculated and the above process is repeated.

[0079] During the movement of the quadruped robot, the movement modes of the actuator modules are predefined.

[0080] See also Figure 6As shown in the walking state diagram, the air valve on the fourth actuator 114 is opened to inflate it, and the first actuator 111, the second actuator 112 and the third actuator 113 remain stationary. Due to the friction between the first actuator 111, the second actuator 112 and the third actuator 113 and the ground, the robot moves forward as a whole during the bending process. Then, the air valve on the third actuator 113 is opened, and the air valve on the fourth actuator 114 is closed. Due to the friction between the first actuator 111, the second actuator 112 and the fourth actuator 114 and the ground, the robot moves forward as a whole during the bending process. By alternating the operation of the fourth actuator 114 and the third actuator 113, the effect of rapid forward movement is achieved.

[0081] See also Figure 7 As shown in the schematic diagram of the steering state, in the left turn mode, the third actuator 113 bends to lift the entire robot, and the second actuator 112 and the fourth actuator 114 bend alternately back and forth to make the robot turn left.

[0082] In a further embodiment, the pneumatic drive system can provide variable output force and movement speed, allowing the robot to adjust the gait and angle of each leg according to the terrain characteristics.

[0083] For example, on sandy ground, the robot may use a longer stride to reduce the specific ground contact pressure; on rocky ground, the robot may take a shorter stride and increase the foot contact area to prevent losing balance.

[0084] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for quadruped robot to adapt to terrain, applied to a pneumatically driven quadruped flexible robot, characterized in that: The method comprises the following steps: S1. Collecting pressure data of the robot in real time, and extracting features from the pressure data, wherein the feature extraction at least includes calculating the average pressure, pressure standard deviation, and pressure difference characteristic value of the pressure data; S2. Determine the current terrain type through a decision tree algorithm according to the result of the feature extraction, and preset the target air pressure required for the robot to pass through the current terrain; S3, obtaining the current actual air pressure of the robot, and calculating the air pressure error according to the target air pressure and the actual air pressure; S4, calculating the air pressure adjustment amount by using a PI algorithm according to the air pressure error and the actual air pressure fed back in real time; S5. Determine whether the air pressure adjustment amount is greater than zero. If so, return to step S3; if not, the robot keeps running.

2. The method for quadruped robot to adapt to terrain according to claim 1, characterized in that: The S1 also includes performing data filtering processing on the pressure data, which satisfies the calculation formula: in, For time point The filtered value of is the number of pressure data, is the original pressure data.

3. The method for quadruped robot to adapt to terrain according to claim 1, characterized in that: The calculating the average pressure, the pressure standard deviation and the pressure difference characteristic value of the pressure data specifically includes: The average pressure is recorded as , which satisfies the calculation formula: in, , , , are the pressures on the robot’s four legs, respectively; The pressure standard deviation is recorded as , which satisfies the calculation formula: The pressure difference characteristic value is recorded as , which satisfies the calculation formula: 。 4. The method for quadruped robot to adapt to terrain according to claim 1, characterized in that: The terrain types include flat land, slightly depressed land, severely depressed land, slightly raised land, and severely raised land.

5. The method for quadruped robot to adapt to terrain according to claim 1, characterized in that: The PI algorithm is used to calculate the air pressure adjustment amount, which satisfies the calculation formula: in, is the air pressure adjustment amount, is the proportional gain, is the error between the current actual air pressure and the target air pressure, is the integral gain, From the initial time to the current time The error integral of .

6. A system for quadruped robot to adapt to terrain, characterized in that: The robot body (100) comprises: Actuator module; Communication module; A driving module, comprising an air valve and an optocoupler driving circuit, wherein the optocoupler driving circuit is electrically connected to the air valve to drive the opening and closing of the air valve; A sensor module, comprising a thin film pressure sensor (150) and an air pressure sensor, wherein the thin film pressure sensor (150) is arranged at the free end of the actuator module, and the air pressure sensor is arranged at the air valve; and The control module includes a microcontroller and a host computer. The microcontroller is in communication connection with the host computer and controls the switch signal quantity of the gas valve according to the received motion signal of the actuator module.

7. The system for quadruped robot to adapt to terrain according to claim 6, characterized in that: The actuator module comprises a first actuator (111), a second actuator (112), a third actuator (113) and a fourth actuator (114), wherein: The free ends of the first actuator (111), the second actuator (112), the third actuator (113) and the fourth actuator (114) that are in contact with the ground have a rounded structure; Ends of the first actuator (111), the second actuator (112), the third actuator (113) and the fourth actuator (114) away from the free end are fixed to the circumferential side wall of the middle piece (170) in sequence through the fixing piece (160).

8. The system for quadruped robot to adapt to terrain according to claim 7, characterized in that: The first actuator (111), the second actuator (112), the third actuator (113) and the fourth actuator (114) are all provided with: An air bag (140) and an air hole (130) are connected to each other, and the air hole (130) is connected to the air valve; A constraint layer (120), the constraint layer wrapping the airbag (140) and the air hole (130), the air hole (130) being ventilated so that the airbag (140) expands and drives the constraint layer (120) to deform, causing the corresponding actuator module to move.

9. The quadruped robot adaptive terrain system according to claim 7, characterized in that: The first actuator (111), the second actuator (112), the third actuator (113), and the fourth actuator (114) are all wrinkle-free pneumatic soft actuators.

10. The system for quadruped robot to adapt to terrain according to claim 6, characterized in that: The model of the microcontroller is STM32F407ZET6.

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