CN101216711A - Hierarchical control device and control method for amphibious mechanical crabs - Google Patents

Abstract

The invention provides a hierarchical control device and control method for amphibious mechanical crabs. Its composition includes the upper-level organization-level control part composed of S3C44B0 as the core ARM system; the coordination-level control part composed of an AVR single-chip ATmega128L; the execution-level control composed of 8 walking foot drive modules and a multi-sensor signal acquisition module. part; the control signal is input to the upper-level organization-level control part, and the coordination-level control part is connected between the upper-level organization-level control part and the executive-level control part, and the executive-level control part communicates with the joint drive unit through the 485 bus communication protocol. The present invention divides the system into three levels: organization level, monitoring and coordination level, and execution level based on the design principle of hierarchical distribution. Each distributed controller can work independently, and can communicate and exchange with the upper level or the same level through the communication line. information. This hierarchical structure combines the advantages of centralized structure and distributed structure, with high global and local control performance and reliable operation.

Description

Hierarchical control device and control method for amphibious mechanical crabs

(1) Technical field

The invention relates to a control device for an intelligent robot, and also relates to a control method for an intelligent robot. Specifically, the invention relates to a control device and a control method of an amphibious mechanical crab-like multi-legged robot.

(2) Background technology

Introduction to the amphibious mechanical crab: The shape and function of the robot are based on the river crab as a biological prototype. There are eight walking legs, each with three driving joints; driven by 24 servo motors, forming 24 degrees of freedom. The controller is controlled by DSP, and the whole is sealed by a rubber jacket, simulating various walking gaits of crabs, and can realize fourteen movements such as forward, sideways, left and right turns, and backwards flexibly in an amphibious environment. Each walking foot is equipped with a force sensor to sense the external environment, detect whether the toe lands and whether the walking foot encounters obstacles, etc., and provide information for the path planning of the walking foot. The hardware framework of the system adopts an embedded structure, with ARM system and DSP chip as the core controller, to complete the planning of complex motion and the calculation of coordination tasks. The system uses infrared remote sensing, force sensor, vision and other sensors, and uses multi-sensor information fusion technology to identify the external environment in real time, making it highly intelligent. It can realize forward, backward, left and right sideways and turns at any position, any angle, and any direction in environments such as beaches, flat land, grassland, swamps, and underwater.

The amphibious bionic robot crab walks in a complex amphibious environment and has high requirements for the control system. In order to enable the robot crab to complete certain tasks, it is first necessary to analyze the functional requirements of the robot for the control system according to its mechanism characteristics and movement characteristics. , establish the hardware control platform and plan the software structure. The robot crab is a complex controlled system, each of its walking legs is a multi-degree-of-freedom serial arm, to achieve effective control, in addition to the accurate and efficient control of the three driving joints of each walking The walking legs need to coordinate with each other to produce the required gait and complete a certain task together. Therefore, the information that the robot crab needs to process during the movement is extremely complex, and the requirements are parallel and clear division of labor.

In order to realize the flexible and all-round walking of the robot, the main requirements for its control system are as follows:

(1) Multi-degree-of-freedom coordinated control. The robot has a total of 24 driving joints. Whether it is omni-directional walking or multi-functional realization, it is realized through the coordinated movement between the driving joints. Therefore, these joints must be coordinated and controlled. The evaluation index is the position of each joint. , speed, acceleration coordination accuracy.

(2) Timely response, strong real-time performance, and comprehensive decision-making ability. During the movement of the robot, the conditions of the road surface and the surrounding environment are random. For these unexpected events, the robot must be able to respond in time and make reasonable decisions, otherwise serious consequences will occur. The evaluation index is the controller's Computing speed, communication bandwidth between modules.

(3) Intelligent, with strong autonomy, minimizing human intervention. Compared with traditional automatic machines that focus on their own actions, the control system of bionic robots focuses more on the relationship between the robot body, the surrounding environment, and the operating object.

(4) It is easy to expand and has the ability to increase control points. With the deepening of the research, the robot may need to add some capabilities, such as the intelligent module for detecting the surrounding environment and its own situation, the gait planning module for different road conditions of the robot, etc. The evaluation index is the redundancy of the software and hardware interfaces of the control system

(5) Provide a friendly man-machine interface. The interface is the interface between people and the control system. Through it, on the one hand, the operator can convey his intentions to the control system in detail, and on the other hand, he can also know the current status of the robot. The evaluation indicators are real-time and information volume.

The current robot control system usually has two basic structural forms: centralized structure and distributed structure. The former has the advantages of direct control, high effectiveness, and is convenient for system analysis and design; the disadvantage is that if the control center fails, the entire system will be paralyzed and the reliability is not high. The latter is connected by the main controller to several distributed controllers, each Each distributed controller has its own control objects and goals. Its advantage is that local failures will not affect the overall situation, and the reliability is high; the disadvantage is that the overall control performance is poor, and the overall coordinated operation is difficult.

(3) Contents of the invention

The purpose of the present invention is to provide a hierarchical control device for amphibious mechanical crabs with high effectiveness, convenient system analysis and design, local failure will not affect the overall situation, high reliability, good overall control performance, and good global coordinated operation effect. The object of the present invention is also to provide a hierarchical control method of the amphibious mechanical crab.

The purpose of the present invention is achieved like this:

The hierarchical control device of the amphibious mechanical crab includes three parts: the upper organization level, the middle coordination level and the lower execution level; the upper organization level control system is mainly composed of S3C44B0 as the core ARM system, and the peripheral expansion includes wireless data transmission module SRWKF-108, infrared Remote control interface, Can communication interface MCP2510, RS232 interface MAX232, LCD module and Intenet Ethernet interface RTL8019AS; the coordination level control system is composed of an AVR microcontroller ATmega128L, which includes the sonar ring sensor information processing system and the three-axis gyro sensor information processing system , variable structure force sensor information processing system, walking foot 1 coordination controller ATmega16L, walking foot 2 coordination controller ATmega16L, walking foot 3 coordination controller ATmega16L, walking foot 4 coordination controller ATmega16L, walking foot 5 coordination controller ATmega16L, Walking foot 6 coordination controller ATmega16L, walking foot 7 coordination controller ATmega16L, walking foot 8 coordination controller ATmega16L; the execution level control system is a modular structure, consisting of 8 walking foot drive modules and a multi-sensor signal acquisition module, each A walking foot driving module includes three drivers: heel joint driver, hip joint driver and tibial joint driver; multi-sensor signal acquisition module includes: sonar controller Msp430F149, force sensor data processing XC2S100 and pressure sensor data acquisition Msp430F149; each walking The foot system is a module of its own, which specifically controls the movement of each joint on each walking foot. It consists of 1 piece of AVR single-chip ATmega16L and 3 pieces of TI MSP430F1222 single-chip. ATmega16L is mainly responsible for the communication of the motor servo driver and the signal acquisition of the joint potentiometer. MSP430F1222 constitutes the servo driver of each joint motor of each walking foot, which is mainly responsible for executing the motor control instructions sent by the coordination level, and servo-driving the joint motors. The sensor module is mainly composed of an AVR microcontroller ATmega128L, which is responsible for the acquisition and processing of the upper force signal of each walking foot, the signal acquisition of the ultrasonic sensor array, and the expansion of new peripherals. The control signal is input to the upper-level organization-level control part, and the coordination-level control part is connected between the upper-level organization-level control part and the executive-level control part, and the executive-level control part communicates with the joint drive unit through the 485 bus communication protocol.

The core chip of the walking foot drive module of the hierarchical control device for amphibious mechanical crabs of the present invention is composed of 3 microprocessors MSP430f1222 and a slice of ATmega16L, a slice of Msp430F1222, power amplifier circuit, photoelectric encoder feedback circuit to form a motion controller, Msp430F1222 and amplifier Quantitative photoelectric encoder, potentiometer, PWM power amplifier are all connected, and connected with crab foot joint coordinator through parallel interface; Msp430F1222, PWM power amplifier, motor M and potentiometer constitute the absolute position closed-loop detection system, while The amplifier, the motor M and the photoelectric encoder form an incremental position and speed feedback closed-loop system through the photoelectric encoder interface, and the entire controller module is connected with the organization-level walking foot coordination controller through a parallel communication interface.

The hierarchical control method of the amphibious mechanical crab is as follows:

The gait planning module judges the current state of the robot based on the information provided by the sensor, and then plans the angles of each joint of the robot's next posture according to the selected coordinate system, forward kinematics and inverse kinematics of the robot; The joint angle is sent to each servo control unit in the lower layer according to the command format specified in the communication protocol according to a certain cycle; the function of the feedback interrupt module is to send a feedback signal to the upper computer when the position of each joint reaches the ideal position, and the upper computer uses the interrupt Accept this feedback information and start the transmission of the next position command; the display module displays the status of the robot on the LCD screen; the wireless remote control module is used for the robot crab to receive the decision-making command of the controller to make it controllable.

After the whole control system starts to work after the switch is turned on, the first step is to initialize the system and reset the position of each joint. After the initialization and reset of each joint, the system waits for the controller command. After the instruction, the upper-layer controller receives the instruction signal, controls the motor to perform corresponding actions according to the instructions and data transmitted by the upper-layer main controller, and determines whether the execution is completed according to the feedback result, and then waits for the next instruction. From the command to the data control motor, it needs to go through the communication interruption judgment program and the communication interruption subroutine, and decompose the command into 8 parameters of the three joints of the walking foot. After executing the single joint position servo subroutine, the corresponding control will be carried out according to the parameters of each joint. An execution judgment instruction to control whether the program is finally executed; when the whole system is executed, the artificial wireless remote control makes its movement stop, changes the movement instruction or the task is not finally completed, it will return to the instruction waiting state; the master controller at the upper layer passes The instructions transmitted by RS485 to the lower joint drive controller should include information such as the rotation direction, rotation angle and rotational angular velocity of the joint; and the joint drive controller will feed back information such as the joint rotation angle and the current state of the walking foot to the upper position in real time through the RS485 bus. machine.

Aiming at the characteristics of mechanical crab control, the present invention proposes a hierarchical control system, which absorbs the advantages of both the centralized structure and the distributed structure. The system is divided into three levels based on the design principle of hierarchical distribution: organization level, monitoring and coordination level, and execution level. Each distributed controller can work independently, and communicate and exchange information with the upper level or the same level through communication lines. This hierarchical structure combines the advantages of centralized structure and distributed structure, so its global and local control performance is high, and its operation is reliable.

According to the complex control system requirements of amphibious mechanical crabs, the present invention provides an optimal control method for amphibious mechanical crabs based on a hierarchical control system, which includes two parts: a hierarchical control device and a control method. Both the control device and the control method adopt the three-level coordination processing method of organization level, monitoring coordination level and execution level. This control method is suitable for controlling all multi-legged robots. The hierarchical control system absorbs the advantages of centralized and distributed structures. It has high effectiveness, is convenient for system analysis and design, and local failures will not affect the overall situation. Reliability High performance, good overall control performance, and good overall coordinated operation effect. It divides the system into three levels: organization level, monitoring and coordination level, and execution level based on the design principle of hierarchical distribution. Each distributed controller can work independently, and can communicate and exchange information with the upper level or the same level through communication lines. . This hierarchical structure combines the advantages of centralized structure and distributed structure, so its global and local control performance is high, and its operation is reliable. Figure 1 is a schematic diagram of the hierarchical control system structure.

The basic principle of hierarchical control: the organization level represents the dominant idea of the control system, has the highest level of intelligence, involves the representation and processing of knowledge (electronic map), and is dominated by artificial intelligence (path planning, cluster collaboration). Human intervention is possible in the process, and by sending command information to the robot crab, its walking path and cooperation strategy can be artificially changed; the coordination level is the connection device between the organization level and the execution level, involving the representation of decision-making methods, and is controlled by artificial intelligence and operations research. It plays a leading role; the execution level is the lowest level of the intelligent control system, which requires the highest control precision and is controlled by conventional control theory.

The control system of the robot crab involves the coordinated control of 24 motors, the signal acquisition and processing of 8 groups of variable structure force sensors, the acquisition and processing of three-axis position and attitude gyro signals, the generation of amphibious bionic gait, the obstacle avoidance path planning, the human Computer interaction, management of wireless and infrared communication, etc., is a very large system. "Decomposition" and "coordination" are the most basic design principles of large-scale system control.

The hierarchical control scheme is considered to be an ideal scheme to realize the comprehensive control of large systems at present, and it has several forms of decentralized control, distributed control and hierarchical control. The robot crab adopts a hierarchical intelligent control system. The main control unit and the distributed joint drive unit communicate with the 485 bus communication protocol. This distributed structure with clear division of labor and capable of parallel processing facilitates the improvement of calculation, execution speed and Control accuracy, its overall composition structure is shown in Figure 2: the main control system includes three parts: the organization layer, the coordination layer, and the execution layer. Gait rule base, the organization layer is responsible for human-computer interaction, obstacle avoidance strategy calculation, gait generation, etc.; the coordination layer is between the organization layer and the execution layer, including sensor analysis module, gait generation system, single-leg compound action library and various The joint unit action library, the coordination layer is responsible for task coordination; the execution layer includes ultrasonic sensors, variable structure force sensors, three-axis gyroscopes, and joint drivers. The execution layer is mainly responsible for sensor data analysis and gait generation. The bottom layer has a single task and a clear division of labor, such as: responsible for sensor signal acquisition, processing, and precise control of motors.

(4) Description of drawings

Figure 1 is a schematic structural diagram of a hierarchical control system;

Fig. 2 is the hierarchical control system of the robot crab;

Fig. 3 is the overall hardware structure of the robotic crab control system;

Figure 4 is the composition of the motion controller system;

Figure 5 is a wiring diagram of the power amplifier circuit L6203;

Fig. 6 is a photoelectric isolation circuit;

Fig. 7 is to distinguish steering circuit and its waveform diagram;

Figure 8 is a schematic diagram of the application of the infinite data transmission module;

Fig. 9 is the structure of the infrared communication system of the host;

Figure 10 is an internal electrical connection diagram of the infrared remote controller;

Figure 11 is the wiring of the RS485 communication chip HVD3082;

Fig. 12 is a schematic diagram of an Ethernet interface circuit;

Fig. 13 is a CAN bus interface circuit diagram;

Fig. 14 is the layered and hierarchical control system of the robot crab;

Figure 15 is a block diagram of the control system software.

(5) Specific implementation methods

The present invention is described in more detail below in conjunction with accompanying drawing example:

Combined with Figure 1, Figure 2 and Figure 3, it includes three parts: the upper organizational level, the middle coordination level and the lower execution level. The upper organization-level control system is mainly composed of S3C44B0 as the core ARM system, and peripheral extensions include wireless data transmission module SRWKF-108, infrared remote control interface, Can communication interface MCP2510, RS232 interface MAX232, liquid crystal display module and Intenet Ethernet interface RTL8019AS, etc. The organization-level functions are mainly responsible for accepting user commands, feeding back information to users, and planning the movement strategy of each crab leg according to the on-site environment. The wireless data transmission module SRWKF-108 and the infrared remote control interface are connected to the main robot controller through their respective serial ports to provide Remote control function, Can communication interface MCP2510 and RS232 interface MAX232 provide a variety of download and debugging interfaces for online debugging of robots. The LCD module is connected to the main controller of the robot through the system bus, which provides intuitive parameters and interfaces for robot program debugging and testing. , Intenet Ethernet interface RTL8019AS provides a local area network communication interface for establishing multi-robot collaboration. The coordination level control system consists of an AVR microcontroller ATmega128L, which includes a sonar ring sensor information processing system, a three-axis gyro sensor information processing system, a variable structure force sensor information processing system, walking foot 1 coordination controller ATmega16L, walking foot 2 coordination Controller ATmega16L, walking foot 3 coordination controller ATmega16L, walking foot 4 coordination controller ATmega16L, walking foot 5 coordination controller ATmega16L, walking foot 6 coordination controller ATmega16L, walking foot 7 coordination controller ATmega16L, walking foot 8 coordination controller ATmega16L. The coordination level is responsible for coordinating various gaits. The gait of the robot crab is the basic unit of robot movement and the basic guarantee for the decision-making system. It includes some conventional gaits, such as high-profile quadrupeds in water environments. Walking gait, low-profile M-shaped five-legged landing gait, etc., also includes some unconventional gaits, such as the Nth (N=1~3) foot-breaking gait, water environment obstacle-crossing gait, etc. Coordinated control. The choice of gait is related to the external environment. The sonar ring sensor information processing system analyzes and processes the monitoring data returned by the sonar controller through a piece of Msp430F149. It mainly detects long-distance obstacles and underwater communication. The three-axis gyro sensor information processing system processes and analyzes the force sensor data in the gyro XC2S100, and mainly detects the deflection angle of the robot body in the environment to ensure that the robot cannot fall over. The variable structure force sensor information processing system collects data through a piece of Msp430F149. It mainly monitors short-distance obstacles, pits, steps, slopes, etc., and performs real-time detection of the robot's walking process to ensure that it will not be damaged or dropped. The purpose of processing and analyzing the data of the above three sensors is to add external sensing devices to the robot, so that the robot can better adapt to the environment, advance with an optimal gait, and improve work efficiency. The executive-level control system adopts a modular approach and consists of 8 walking foot drive modules and a multi-sensor signal acquisition module. Each walking foot drive module includes three drives: heel joint drive, femoral joint drive and tibial joint drive; The sensor signal acquisition module includes: sonar controller (Msp430F149), force sensor data processing XC2S100 (gyro) and pressure sensor data acquisition (Msp430F149). Each walking foot system is a module of its own, which specifically controls the movement of each joint on each walking foot. It is composed of 1 piece of AVR microcontroller ATmega16L and 3 pieces of TI MSP430F1222 singlechip. ATmega16L is mainly responsible for the communication of the motor servo driver and the joint potentiometer. For signal acquisition, MSP430F1222 constitutes the servo driver of each joint motor of each walking foot, which is mainly responsible for executing the motor control instructions sent by the coordination level, and servo-driving the joint motors. The sensor module is mainly composed of an AVR microcontroller ATmega128L, which is responsible for the acquisition and processing of the upper force signal of each walking foot, the signal acquisition of the ultrasonic sensor array, and the expansion of new peripherals.

The detailed composition of the overall hardware structure of the amphibious bionic robot crab is shown in Figure 3. The entire working process is: the upper-level organizational-level peripheral expansion module wireless data transmission module SRWKF-108, infrared remote control interface, Can communication interface MCP2510, RS232 interface MAX232, liquid crystal display Module and Intenet Ethernet interface RTL8019AS provide basic hardware interface for robot remote wireless remote control, program online debugging, human-computer interaction interface, LAN communication interface; sonar controller (Msp430F149), force sensor data processing XC2S100 (gyroscope) and pressure sensor Data acquisition (Msp430F149) is the peripheral detection module of the robot, which provides real-time parameters for the working environment of the robot. These parameters are continuously passed through the coordination level sonar ring sensor information processing system, three-axis gyro sensor information processing system and variable structure force sensor information. After processing, the processing system feeds back to the S3C44B0 master control at the upper organization level. The master control sends out different gait library instructions according to the returned data. For each joint of the execution level, the gait adapted to different environments is completed. The walking process is monitored in real time, and the walking gait and path are changed accordingly according to the external environment, so that it can move in the optimal and fastest way. .

1. Crab foot joint motor drive module

The crab foot joint motor drive module can drive three joint motors on a crab foot. The core chip is composed of three microprocessors MSP430f1222 and one ATmega16L. MSP430f1222 is mainly responsible for the servo drive of a single motor; ATmega16L is responsible for the coordinated control of the three motors , Communication with host computer, acquisition of potentiometer signal.

Motor Controller Hardware Composition

Combined with Figure 4, the motion controller is composed of a minimum system of Msp430F1222, including: a piece of Msp430F1222, a power amplifier circuit, and a photoelectric encoder feedback circuit. Msp430F1222 is connected to an incremental photoelectric encoder, potentiometer, and PWM power amplifier. The foot joint coordinator is connected through a parallel interface. Msp430F1222, PWM power amplifier, motor M and potentiometer constitute an absolute position closed-loop detection system, while Msp430F1222, PWM power amplifier, motor M and photoelectric encoder form an incremental position and speed feedback closed-loop system through the photoelectric encoder interface, the entire control The controller module is connected to the organization-level walking foot coordination controller through the parallel communication interface to transmit data. After receiving the instruction, Msp430F1222 outputs a PWM signal through power amplification to control the rotation of the motor M, and the potentiometer monitors the absolute position of the motor M. , the photoelectric encoder starts counting feedback, and the speed, acceleration and position of the motor M can be adjusted and controlled, so that the purpose of controlling the robot joints is achieved.

[1] Power amplifier drive circuit

Combined with Figure 5, the power amplifier circuit requires high performance to ensure the stable operation of the robot crab control system. Selecting an integrated power amplifier with appropriate performance parameters, compared with a power amplifier circuit designed with discrete components, not only can reduce the volume of the power amplifier circuit and improve the overall performance, but also has a variety of protection circuits designed in the integrated power amplifier, which can reduce system power consumption. The possibility of failure and enhance the reliability of the system. Therefore, when designing the power drive circuit, after carefully comparing the size, performance, price and other aspects of the chip, the full-bridge motor drive chip L6203 produced by ST Company was selected.

The L620x series integrated power amplifier circuit is specially designed for small and medium-sized motor control. It integrates DMOS (depletion mode field effect transistor) power switch tube, CMOS and bipolar circuit inside; the maximum supply voltage can reach 48V, and the output current Up to 5A, with overheat protection and overload protection; provide a maximum dead time of 40ns; the highest frequency can reach 100KHz, and the input is compatible with TTL and CMOS levels.

[2] Photoelectric encoder feedback circuit

Combined with Figure 6, the encoder is the feedback channel of the motor. The speed, direction and position of the motor are obtained through the feedback pulse of the encoder. The circuit consists of four parts: a photoelectric isolation circuit, a steering circuit, a subdivision circuit, and a counter. The photoelectric isolation circuit is mainly composed of two high-speed photoelectric couplers 6N137, which can respond to high-frequency pulses up to 10MHz to photoelectrically isolate the A and B two-channel signals with a phase difference of 90° from the motor, and can effectively eliminate the impact of external electromagnetic signals on subsequent counter interference.

Combining with Figure 7, the steering circuit is composed of a D flip-flop, and the A and B two-phase pulses processed by light interval shaping are respectively input to the D terminal and CP terminal of the D flip-flop, so the CP terminal of the D flip-flop is at the A pulse Rising edge trigger. Since the A and B pulses have a phase difference of 90°, when rotating forward, the B pulse is ahead of the A pulse by 90°, and the trigger is always triggered when the B pulse is at a high level. It can be seen from the figure that Q=1 means forward rotation, and reverse rotation When turning, the A pulse is 90° ahead of the B pulse, and the trigger is always triggered when the B pulse is at a low level. At this time, Q=0, which means inversion.

2. Wireless data transmission module

In order to realize the controllability of the robot crab and give feedback to the data when it is moving, a SRWF-108 micro-power wireless data transmission module is installed in the upper control system of the robot crab, which includes: a wireless joystick (transmitting) and a receiving module, and The receiving module is composed of receiving antenna, data processing module (RF IC and AtmelMCU), and serial port UART. The transmission characteristics of this module are as follows: ①The transmission distance is relatively long. In the case of line of sight, the antenna height is greater than 3m, and the reliable transmission distance is greater than 3000m; ②It can be suitable for standard or non-standard user protocols; ③Support multi-channel, multi-rate; ④Dual Serial port, three interface modes; ⑤Support two data structures with or without verification.

The infinite data transmission module can provide standard RS-232, RS-485 and UART (TTL level) three interface methods, which can be directly connected with computers, user RS-485 equipment, single-chip microcomputers or other UART devices, and its communication channel It is half-duplex and most suitable for point-to-multipoint communication. The schematic diagram of the application is shown in Figure 8. The working process is: manipulating the command of the launch handle panel in the hand, the radio wave signal command is transmitted by the transmitting antenna, and the radio wave signal is received by the antenna in Figure 8, and after being received by the RF IC, it is analyzed and verified by the processor AtmelMCU, and it is useless to filter out The useful signal command data is transmitted to the robot main controller ARM through the serial port UART, so that the ARM executes the corresponding command program through the transmitted command to achieve the purpose of remote control of the robot.

3. Infrared remote control module

The infrared communication system of the robot crab consists of two parts: the infrared interface of the main control processor and the infrared remote control handle. The remote control handle consists of three parts: keyboard scanning, infrared decoding and encoding, and infrared transceiver. The basic principle of infrared communication is that the sending end modulates the baseband binary signal into a series of pulse signals, and then emits the infrared signal through the infrared emitting tube. The serial infrared transmission adopts a specific pulse coding standard, which is different from the RS232 serial transmission standard. If serial infrared communication is performed between two devices, conversion between RS232 coding and IrDA coding is required. The infrared communication interface consists of an infrared transceiver and an infrared codec.

lrDA stands for Infrared Data Association, the full name of The Infrared Data Association, is an international organization established in June 1993, which specializes in formulating and promoting low-cost infrared data interconnection standards that can be used together, and supports point-to-point working mode. The purpose of IrDA is to formulate standards and protocols realized at a reasonable cost to promote the development of infrared communication technology. IrDA1.0 is referred to as SIR Serial InfraRed, which is an asynchronous, half-duplex infrared communication method based on HP-SIR. Relying on the system's asynchronous communication transceiver UART, SIR realizes infrared data transmission through the encoding and decoding process 3/16EnDec of waveform compression of serial data pulses and waveform expansion of electrical pulses of received optical signals. Considering that both UART0 and UART1 of the main control processor S3C44B0 have IrDA1.0 mode, IrDA1.0 can support the highest communication rate of 115.2kbps. In this way, the infrared interface of the main control is relatively simple, and UART1 is selected as the infrared communication port. The infrared transceiver module uses HSDL-3201, and the infrared transceiver includes two parts: a transmitter and a receiver. The transmitter (transmitter) converts the bit-modulated pulse received from I/O or ENDEC into an infrared pulse and sends it out; the receiver (receiver) detects the infrared light pulse and converts it into a TTL or CMOS electrical pulse. The structure of the infrared communication system of the host is shown in Figure 9.

The remote control handle of the robot crab consists of three parts: keyboard scanning, infrared decoding and encoding, and infrared transceiver. As a handheld device, it focuses on low power consumption. Msp430F1222 is selected as the main processor, which is responsible for keyboard scanning and serial data transmission. The infrared transceiver module is selected HSDL-3201, the infrared decoding encoder uses the dedicated HSDL7001, the chip adapts to the IrDA1.0 physical layer specification, the interface is compatible with the SIR transceiver, it can be connected with the standard 16550UART or the UART of the MCU, and can send/receive 1.63us or 3/16 pulse form, with internal or external clock mode, baud rate programmable. Figure 10 is an internal electrical connection diagram of the infrared remote controller.

The whole workflow: as shown in Figure 10, firstly the main processor is in a dormant state when no keyboard is pressed. The processor wakes up, and the MSP430F1222 processor executes keyboard scanning and debounce programs through parallel signals, and then sends the key value to the infrared decoding code HSDL7001, which is encoded by the HSDL7001 and sent through the infrared transceiver HSDL-3201. After sending, the main processor will enter dormant state. After receiving the signal, the robot crab's infrared transceiver HSDL-3201 (Figure 9) sends the coded signal to the infrared codec of the main processor S3C44B0, obtains the key value through decoding, and transmits it to the robot's main controller through a serial signal device, and then execute the instruction of the key value.

4. Network communication interface

The network communication interface includes: RS485 asynchronous serial bus communication, Ethernet interface and CAN bus interface. RS485 communication provides information transmission between the upper and lower control systems, Ethernet interface transmits information for the local area network established by multiple robots, CAN bus is an expansion bus, which can be connected with some long-distance underwater communication Modem, industrial GPS and other equipment.

(1) RS485 hardware circuit

In the double-layer control system of the bionic robot crab, the RS485 asynchronous serial bus communication mode is selected between the upper and lower control systems. superior.

The RS485 standard was originally formulated and released by the Electronics Industries Association (EIA) in 1983, and was later revised by the Communications Industry Association (TIA) and named TEA/EIA-485A. RS485 is an electrical interface specification, suitable for the distance between devices less than 1200m, and its maximum transmission rate is 1MB/s. The RS485 standard defines a multi-point, two-way (half-duplex) communication link based on a single-pair balanced line. It is an extremely economical communication platform with relatively high noise suppression, transmission rate, transmission distance and wide common mode range. . The RS485 serial bus interface standard transmits signals in a differential balanced manner, has a strong ability to resist common mode interference, and allows one transmitter on a pair of twisted pairs to drive multiple load devices. This bus is generally used in industrial field control systems standard for data transmission.

The main control system processor S3C44B0 used in the study has two serial communication interfaces, and Mega16 has a serial port, which can be selected as a synchronous serial port (SPI) or an asynchronous serial port (UART) by software. As long as you choose a bus driver that supports the RS485 standard, you can form the RS485 bus system we need by connecting it as the upper computer with the Mega16 as the lower computer. After comparison, we choose HVD3082 as the driver chip for the RS485 communication bus. HVD3082 is produced by American TI company, it fully meets the TIA/EIA-485A standard, 5V power supply, extremely low power consumption, operating current is less than 0.3mA, shutdown current is about 1nA, the bus supports 256 nodes, Figure 11 is the wiring diagram of HVD3082 .

The communication experiment proves that the RS485 serial bus interface circuit is simple, the performance is reliable, the anti-interference ability is strong, and it is suitable for the data transmission system of the machine crab. In the experiment, in order to control the rotation of the joints conveniently and to feed back the information to the experimenters, the RS232 asynchronous serial port is still used to exchange data between the PC and the S3C44B0. The RS232 serial port circuit is designed.

(2) RS485 communication protocol

The data that needs to be communicated on the RS485 bus in the control system include: 24 drive status initialization data, 24 joint position data, 24 joint speed data, 24 joint acceleration data, and 24 joint potentiometer data. Obviously, the amount of data is very large. Large ones, when they shuttle on the same data line, have high requirements on the communication protocol. From the perspective of communication speed and reliability, the selected serial communication format is: 8 data bits, 1 start bit, 1 stop bit, no parity bit, and the communication rate is 115200bps. Due to the large amount of data in this system, in the bus network composed of a master node and multiple slave nodes, the master-slave response mode is adopted, and the master node initiates and controls the network and interface communication on the network. Each slave node has an identification address, and only when it receives a data frame matching its own address, it will have corresponding processing and reply the result to the master node. There are two main communication processes in the system: sending motion parameters (position, speed, acceleration) to the joint motor driver node; obtaining joint motion parameters (position, speed, acceleration, potentiometer value) from the joint motor driver.

In order to ensure unimpeded communication and the smooth execution of local affairs of slave nodes, a communication method of time-limited exit is designed, that is, when a data frame that does not match its own address is received, the communication port is temporarily closed. This not only guarantees the execution time of local transactions, but also avoids the two-way interference that may be caused by the slave nodes often being on the Internet. Therefore, in the software design of the upper and lower computers, secondary error detection, retransmission, time-limited exit and re-shake to establish a connection and other communication mechanisms. During the debugging, it was found that when some nodes work abnormally or even the communication network is completely paralyzed, other nodes can independently complete local affairs such as data collection, abnormal alarm and real-time data storage. Once the faulty node is eliminated, the communication can be restored.

(3) Ethernet interface hardware part

Ethernet is not only a connection standard for computers to access local area networks, but also a communication protocol for data sharing of network interconnection devices. It uses carrier sense multi-point access CSMA/CD technology with collision detection. Due to the substantial increase in the transmission rate of Ethernet, the industrialization of physical layer standards and the formation of Ethernet hub technology, the emergence of Gigabit Ethernet technology and collision-free full-duplex fiber optic technology, this advanced network technology has been promoted to industrial control networks. In the process, industrial Ethernet technology was formed. Compared with the current fieldbus-based control network, the control network based on industrial Ethernet technology is a low-cost (many commercial Ethernet chipsets and technologies can be borrowed), high-performance control network solutions. The Ethernet interface is a key interface for the ARM system, mainly because its communication speed is very fast (10Mbps), and it can be quickly debugged through the program. Compared with the JTAG interface debugging, the speed can be improved by nearly 100 times, the 4M program takes nearly 1 hour to download through JTAG, but it only takes 32 seconds to download through the network port.

The Ethernet interface adopts the RTL8019AS Ethernet controller produced by Realted Company, supports IEEE802.3 and 8-bit or 16-bit data bus, built-in 16KB SRAM is used for sending and receiving buffer, full-duplex, and the sending and receiving can reach 10Mbps at the same time, and supports 10Base5, 10Base2, 10BaseT, and can automatically detect the connected medium, which occupies a considerable proportion of ISA bus network cards. There are 3 interface modes between RTL8019AS and the host, namely jumper mode, PnP mode and RT mode. In the embedded system, neither EEPROM nor ISA bus is used, so the jumper mode is selected, JP is connected to high level, and some settings are determined by pins.

(4) Ethernet interface software part

The communication program related to the Ethernet interface is divided into three parts: RTL8019AS initialization, sending control, and receiving control. The schematic diagram of the interface circuit is shown in Figure 12.

The initialization part completes the initialization work of RTL8019AS before use: setting the registers of the relevant working mode, allocating and initializing the receiving and sending buffers, and initializing the receiving address of the network card.

The working steps of the RTL8019AS initialization program are as follows:

1) Reset RTL8019AS;

2) Select page 0 register, RTL8019AS stops running;

3) Set the data configuration register to 16 bits;

4) Clear the remote DMA counter;

5) Set the receiving buffer interval;

6) Set the receiving configuration register (only receive data packets of its own address);

7) Set the sending configuration register (enable CRC automatic generation and automatic verification);

8) The interrupt register is cleared;

9) Shield all interrupts in RTL8019AS;

10) Set the register (BNRY) pointing to the last page that has been read;

11) select page 1 register;

12) Initialize the physical address;

13) Initialize the multicast address;

14) Set the current receiving end page register;

15) Select the page 0 register and start RTL8019AS to execute the command;

16) Enable the RTL8019AS corresponding interrupt in the host;

The sending part only needs to write the data into the buffer, start to execute the command, and the RTL8019AS will send it automatically. Generally, two Ethernet data packet long spaces are opened up in RAM as sending buffers. When sending data, the two buffers are sent in turn. The data sending verification, bus data packet collision detection and avoidance are all completed by RTL8019AS itself of. The receiving part completes the data receiving task. After RTL8019AS receives the Ethernet data packet, it automatically saves the receiving buffer and sends an interrupt signal. S3C44B0X can read the received data through DMA in the interrupt program.

(5) CAN bus interface

CAN is a field bus with international standards and high performance and price ratio. As an expansion bus, it can be easily connected with some long-distance underwater communication Modem, industrial GPS and other equipment. The CAN bus interface uses MCP2510 with SPI interface from Microchip Technology Inc. as the CAN bus controller. The interface between the controller and the physical bus uses TJA1050 from Philips. The circuit is shown in Figure 13. TJA1050 is a PCA82C250 and the successor of the PCA82C251 high-speed CAN transceiver. The main differences are: ①The best matching of the output signals CANH and CANL makes the electromagnetic radiation lower; ②When the node is not powered, the performance is improved; ③No standby mode.

2. Software module design of the control system

The robot crab adopts three-level hierarchical control. In the design of the robot crab control software, each hardware module also adopts the method of software modularization. As shown in Figure 14, the main control circuit board is composed of a main control processor, a coprocessor, and peripheral circuits. The main control processor is solidified with a reasoning module, a path planning module, and a communication module, and the coprocessor is solidified with a gait library. , communication module, gait coordination module, and obstacle reflex module, and these modules of the coordination level are connected with the gait coordinator, sonar coordinator, force sense coordinator and seat coordinator of the 8 walking feet, and the 8 walking feet The gait coordinator is connected with the drivers of each joint to form a three-joint main control system (circuit board), the sonar ring coordinator and the sonar sensor are coordinated and processed to form the sonar ring signal processing board, the force sense coordinator and the force sense The sensor forms the force signal decoupling board, and the attitude processor and the attitude sensor (gyro) form the electronic gyro system.

The block diagram of the control software is shown in Figure 15. The attitude control of the robot crab is based on position feedback control. The ideal position for the upper computer to transmit the joint rotation angle to the lower computer. The host computer software mainly consists of gait planning module, instruction sending module, feedback interruption module, display module and wireless remote control module.

The gait planning module judges the current state of the robot based on the information provided by the sensor, and then plans the angles of each joint of the robot's next posture according to the selected coordinate system, forward kinematics and inverse kinematics of the robot (defining a behavior library, for joint angles The control can be searched in the behavior library); the command sending module sends the calculated joint angles to the servo control units in the lower layer according to a certain cycle in the command format specified in the communication protocol; the function of the feedback interrupt module is, when each After the joint position reaches the ideal position, a feedback signal is sent to the upper computer, and the upper computer uses an interrupt to receive the feedback information and start the transmission of the next position command; the display module displays the status of the robot on the LCD screen, which is convenient for experimental observation; wireless The remote control module is used for the robot crab to receive the decision-making order of the controller to make it controllable.

The control flow chart in Figure 15 works as follows: After the entire control system is turned on and starts working, the first step is to initialize the system and reset the position of each joint. After the initialization and reset of each joint, the system waits for the controller instruction. After the remote control handle or the infrared remote control sends out the execution command, the upper controller receives the command signal, controls the motor to perform corresponding actions according to the command and data transmitted by the upper master controller, and determines whether the execution is completed according to the feedback result, and then waits The next instruction, the instruction sent by the upper master controller to the data control motor needs to go through the communication interruption judgment program and the communication interruption subroutine, then decompose the instruction into 8 parameters of the three joints of the walking foot, and execute the single joint position servo subroutine. Corresponding control will be carried out according to each joint parameter, and whether the program is finally executed is controlled through an execution judgment instruction. During the execution of the entire system, if the human wireless remote control makes its motion stop, changes the motion command or the task is not finally completed, it will return to the command waiting state. The master controller at the upper level of this system sends instructions to the lower joint drive controller through RS485, which should include information such as the rotation direction, rotation angle, and rotation angular velocity of the joint. The joint drive controller feeds back information such as the joint rotation angle and the current state of the walking foot (swing or support, whether it encounters an obstacle) to the host computer in real time through the RS485 bus.

Claims (4)

1. A hierarchical control device for amphibious mechanical crabs, characterized in that: it includes three parts: an upper-level organization level, a middle-level coordination level and a lower-level execution level; the upper-level organization-level control system is mainly composed of S3C44B0 as the core ARM system, and the peripheral expansion Including wireless data transmission module SRWKF-108, infrared remote control interface, Can communication interface MCP2510, RS232 interface MAX232, liquid crystal display module and Intenet Ethernet interface RTL8019AS; the coordination level control system is composed of an AVR microcontroller ATmega128L, which includes sonar ring sensor information Processing system, three-axis gyro sensor information processing system, variable structure force sensor information processing system, walking foot 1 coordination controller ATmega16L, walking foot 2 coordination controller ATmega16L, walking foot 3 coordination controller ATmega16L, walking foot 4 coordination controller ATmega16L, walking foot 5 coordination controller ATmega16L, walking foot 6 coordination controller ATmega16L, walking foot 7 coordination controller ATmega16L, walking foot 8 coordination controller ATmega16L; the executive level control system is a modular structure, consisting of 8 walking foot drive modules It is composed of a multi-sensor signal acquisition module, and each walking foot drive module includes three drivers: heel joint driver, hip joint driver and tibial joint driver; the multi-sensor signal acquisition module includes: sonar controller Msp430F149, force sensor data processing XC2S100 and pressure sensor data acquisition Msp430F149; each walking foot system forms a module, which specifically controls the movement of each joint on each walking foot. It consists of 1 piece of AVR single-chip ATmega16L and 3 pieces of TI MSP430F1222 single-chip. ATmega16L is mainly responsible for the motor servo drive Communication and joint potentiometer signal acquisition, MSP430F1222 constitutes the servo driver of each joint motor of each walking foot, which is mainly responsible for executing the motor control instructions sent by the coordination level, and servo-driving the joint motors. The sensor module is mainly composed of an AVR microcontroller ATmega128L, which is responsible for the acquisition and processing of the upper force signal of each walking foot, the signal acquisition of the ultrasonic sensor array, and the expansion of new peripherals. The control signal is input to the upper-level organization-level control part, and the coordination-level control part is connected between the upper-level organization-level control part and the executive-level control part, and the executive-level control part communicates with the joint drive unit through the 485 bus communication protocol. 2. the hierarchical control device of the amphibious mechanical crab according to claim 1 is characterized in that: the core chip of the walking foot drive module of the described hierarchical control device is made of 3 microprocessors MSP430f1222 and a slice of ATmega16L, a slice of Msp430F1222, The power amplifier circuit and the photoelectric encoder feedback circuit form the motion controller. Msp430F1222 is connected to the incremental photoelectric encoder, potentiometer, and PWM power amplifier, and is connected to the crab foot joint coordinator through a parallel interface; Msp430F1222, PWM power amplifier, and motor M and potentiometer constitute an absolute position closed-loop detection system, and Msp430F1222, PWM power amplifier, motor M and photoelectric encoder form an incremental position and speed feedback closed-loop system through the photoelectric encoder interface, and the entire controller module communicates with the organization through a parallel communication interface Level walking foot coordination controller is connected. 3. A hierarchical control method for amphibious mechanical crabs, characterized in that: The gait planning module judges the current state of the robot based on the information provided by the sensor, and then plans the angles of each joint of the robot's next posture according to the selected coordinate system, forward kinematics and inverse kinematics of the robot; The joint angle is sent to each servo control unit in the lower layer according to the command format specified in the communication protocol according to a certain cycle; the function of the feedback interrupt module is to send a feedback signal to the upper computer when the position of each joint reaches the ideal position, and the upper computer uses the interrupt Accept this feedback information and start the transmission of the next position command; the display module displays the status of the robot on the LCD screen; the wireless remote control module is used for the robot crab to receive the decision-making command of the controller to make it controllable. 4. The hierarchical control method of amphibious mechanical crabs according to claim 3, characterized in that: after the entire control system is turned on and starts to work, the first step is to perform system initialization and reset of each joint position, and the system is initialized and each joint is reset. Finally, wait for the controller command. When we use the wireless remote control handle or the infrared remote control to issue an action command, the upper controller receives the command signal, controls the motor to perform corresponding actions according to the command and data transmitted by the upper master controller, and Feedback the results to determine whether the execution is complete, and then wait for the next command. The command sent by the upper master controller to the data control motor needs to go through the communication interruption judgment program and the communication interruption subroutine, and then decompose the instruction into 8 walking feet and three joints. parameters, the execution of the single joint position servo subroutine will carry out corresponding control according to the parameters of each joint, and control whether the program is finally executed through an execution judgment instruction; when the entire system is executing, the artificial wireless remote control stops its movement and changes If the motion command or the task is not finally completed, it will return to the command waiting state; the command sent by the upper master controller to the lower joint drive controller through RS485 should include the rotation direction, rotation angle and rotation angular velocity of the joint; and the joint The drive controller feeds back information such as the joint rotation angle and the current state of the walking foot to the host computer in real time through the RS485 bus.

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