Research On Design Of Bionic SMA Actuator And Its Application On Robot

Shape Memory Alloy(SMA),as a special kind of new functional material,is a kind of intelligent material which integrates sensing and driving.It can be used to produce small,highly automated and highly reliable components.So SMA has attracted tremendous attention,and has been widely used in bionic robots,building damping,and the field of aerospace.The following work has been done in this article:Firstly,this paper studied the relevant Chinese and foreign documents,made a deep investigation on the research status of SMA and SMA driven bionic robots,and described the significance of this research project and the main contents of this paper.And then introduced the basic concepts and constitutive models of SMA.Secondly,in order to study the characteristics of SMA,a sampling circuit using Wheatstone bridge is designed to get the resistance value of SMA actuator in real time.An experiment has also been done and showed that SMA's resistance can be a feedback variable.Thirdly,this paper selected the appropriate SMA wire and designed a kind of highperformance SMA actuator.At the same time,according to the project indicators,the mechanical structure of the humanoid wrist was designed and the connection between SMA actuator and wrist joint was determined.Fourthly,using Arduino as the controller,the L298N as the driving device of the SMA actuator,and the encoder as the angle sensor of the wrist joint,the closed loop control system of humanoid wrist was realized.Finally,based on MATLAB/Simulink platform,PID and BP neural network PID control algorithm were written and implemented in experiments,which showed that the humanoid joint's range of angle is 60 degrees and its angular precision is 1 degree.After the experiment,the control system has been moved to Beckhoff embedded controller,and the wrist is integrated with other assembly unit which is made by collaborating colleges.