Design Of Embedded Control System For Hydraulic Walking Robot

A hydraulic-driven biped walking robot prototype has been developed.This paper designs an embedded control system based on this robot prototype to realize its walking function.Firstly,according to the features of the robot prototype and current development trend,five design requirements of the control system are put forward.The communication scheme and embedded real-time operating system are determined according to the requirements.Distributed structure is adopted and the control system is divided into three parts:planning module,sensor module and driving module.Secondly,according to the function requirements of the three modules,the hardware circuit design is completed.In part of software,various tasks to realize the function of the planning module are designed and can be scheduled by uC/OS-III operating system.Real-time Ethernet communication protocol EhterCAT is used to transmit data between different modules.DMP in posture sensor is configured to export the posture of the robot.File system FATFS is ported and a double-buffer-zone method is used to store the key data in the process of the system.Thirdly,the robot joints drive and control method is studied.Considering the disadvantage of the traditional PID control method,a self-tuning fuzzy-PID control method is used to drive the robot joints.With the model of robot joints,the influence on the system of proportion,integral and differential is analyzed in detail.After formulating the fuzzy rules,the simulation result shows that the fuzzy-PID control method is superior to the traditional PID control method when controlling the robot joints.Finally,the experimental platform is set up and experiments to test the performance of the embedded control system are carried out and analyzed.Data transmission experiment shows that the data transmission is stable and accurate.Data acquisition experiment shows no key data missing.In the robot motion control experiments,single joint control experiment proves fuzzy-PID control is more suitable for hydraulic walking robot.Control cycle experiment demonstrates that 4-ms control cycle can meet the demand of the robot control.Multi joints motion experiment indicates that the longer the robot gait cycle is,the better performance the system will have.Robot joint driving ability is insufficient when the cycle is too short.Walking experiment proves the embedded control system can satisfy the need of stable low-speed walk of the robot prototype.