Research On The Sensing And Control System Of The Exoskeleton Robot Based On CompactRIO

The exoskeleton robot is a wearable device that enhances the strength and endurance of the human body.Unlike other wearable robots,the exoskeleton robot has its wearer in the control loop.In this thesis,the sensing and control system of an electro-hydraulic driven lower exoskeleton device is studied in the following parts:Software and hardware of the sensing and control system is developed.The overall structure of sensing and control system is developed according to the actual requirements of the exoskeleton robot.Circuit design and production of several functional modules are performed.The multichannel synchronous data acquisition program is designed based on the CompactRIO controller in Lab VIEW language.The digital sensing technology is used to filter the sensory signals as well.The single-leg control algorithms for the exoskeleton robot are conducted.Aiming at the difficulty in constructing an robot dynamics model accurately,a trajectory tracking strategy is proposed to control the interaction of the end of the motion.In the proposed strategy,only the kinematic model needs to be established,the human-machine interaction force is considered as the control input and the signals of encoder as a tracking reference.The velocity decomposition model of swing phase and support phase is set up respectively,in order to obtain the input of the servo valve PID controller.The kinematic model is verified by MATLAB with minimal error.The mathematical model of the valve-controlled cylinder system and joints of lower limb are established.The simulation is performed on the lower limb joint speed control system,to obtain the reference PID parameters.Experimental of single leg control of exoskeleton robot is studied.A fixed trajectory following experiment,a swing leg test and a lift test of single leg,as well as a walking test are performed.The fixed trajectory following experiment is carried out to verify the accuracy of the servo valve PID controller,which uses the standard human gait data as input and the encoder signal as real-time location feedback.To demonstrate the control algorithm with human-machine force in both gait phase,the swing experiment and the stance phase lifting experiment are performed.Finally,a continuous walking experiment is conducted to test the comprehensive performance of the whole exoskeleton robot.The gait switching between the support phase and the swing phase depends on whether the foot pressure signal reaches a threshold value,which is obtained by summarizing the law of the foot pressure signal when human walks naturally.The experimental results show that the sensing and control system can ensure the stable and reliable operation of the exoskeleton robot.The single-leg control algorithm used in the thesis can meet the requirements of walking as well as complicated action like lifting.The interaction-based control is flexible according to the wearer's feelings,although force feedback control has a certain time delay.