Research On Motion Control Of Capsule Robot Based On IPMC Actuator

Ionic Polymer Metal Composite(IPMC)is a type of electro-active polymer(EAP)material.It has the advantages of low driving voltage,large deformation displacement,good flexibility and ability of working in water-filled environment.When a voltage signal is applied to the IPMC in the thickness direction,the IPMC will have a large bending deformation,which can be used as an actuator.In order to solve the problem that the capsule endoscope for clinical application can't control the position and posture autonomously,a capsule robot with active motion driven by IPMC is designed in this paper.We also design the control system of the capsule robot and use it to realize the control of the forward,turn and clamp motion of the capsule robot.The main contents are as follows.1.The structure of capsule shell is designed and processed.The tail fin of the capsule is designed with bionics knowledge.The drive solution of the capsule robot is determined,for the capsule robot to mainly complete the function of advancement,turning and fixed-point clamping in the digestive tract.Mechanical calculation on the forward and turn modes of the capsule robot is performed,the parameters affecting the movement and turning of the capsule are analyzed.2.The control system of the capsule robot is designed.It can output 4-channel bipolar high current signals,such as sine wave,square wave and combined waveform.The amplitude,frequency and duty cycle of the output signals of each channel are adjustable.The output waveform of the control system is detected by an oscilloscope to verify the correctness of the output signal.3.An open-loop control method for IPMC is proposed.By changing the amplitude,duty ratio and frequency of the control signal,IPMC can swing in one side at the initial equilibrium position and relatively maintain displacement after bending deformation.The results indicate that IPMC can be swing at one side by using an asymmetric amplitude signal and changing the duty cycle.By applying a DC signal to bend IPMC and then applying a high frequency signal,IPMC can keep bending state relatively.4.Using the control system and control signals designed in this paper can achieve control of the capsule to complete the forward,turn and fixed-point clamping motion.In addition,the influence of control signal parameters on the swimming speed and turning angle of the capsule are tested.The experimental results show that the speed of the capsule can reach 4.83mm/s and the turning angle can reach 45°.By changing the parameters of control signal,the speed and turning angle can be adjusted.