The Research On Shape Memory Alloy Wire Driven Wrist And Platform

The traditional mechanical wrist was driven by motor or hydraulic cylinder with a combination of spherical gear, connecting rod and other executive device, which has a complex structure, low power weight ratio. The wrist, as the connection of the arm and hand, its structure, volume, power also directly affect the coordination of the whole robot arm. The traditional mechanical wrist is difficult to meet the requirements of development, so it is meaningful to pursuing the high power weight ratio and compact structure. Shape memory alloy (SMA) has greater advantages on the driving force and the driving displacement compared with other new intelligent materials. So it is meaningful to driven the wrist by SMA replacing of the traditional motor and hydraulic cylinder.First of all, analyze the application of SMA actuator at home and abroad to inspire the SMA wrist structure design. Also, Make an overview of the mechanical wrist and SMA wrist. Then introduce the characteristics of the SMA and material types.Secondly, determine to use the SMA wire partial spring structure as the structure of SMA wrist. Kinematics simulation of the SMA wrist model is carried out using Matlab/Simulink. Set up an experiment table based on LabVIEW to test the drive performance of SMA. Compare the angle displacement result with kinematics simulation and verify it’s rationality. Besides, the power-to-weight ratio of SMA is 3 times higher than that of the mechanical wrist through the comparison between each other, which proved the advantage of high power weight ratio of SMA.Thirdly, designed a single-input fuzzy controller and made a simulation with Matlab/ Simulink to verify the feasibility of the fuzzy controller. Then carried out a Hardware-in-the-Loop Simulation based on Matlab/Real-Time Windows Target (RTWT) semi-kind simulation, and achieved good control effect.Finally, design the structure of double degree of freedom of SMA wrist and realize the pitch and yaw movement with ±45°. Determine the organic glass as the wrist materials. Make an kinematic analysis using the Proe/mechanism module and attain the movement space of the wrist.