Research On Series Elastic Actuator And Application In Mechanical Arm

Series elastic actuator(SEA)is a kind of force output device which has the function of flexible output and bionic elastic drive.It can realize active flexibility control by adding elastic unit and corresponding sensor between load and drive.At present,SEA has been widely used in the fields of walking robot,rehabilitation robot,mechanical exoskeleton etc.Moreover,applying SEA in mechanical arm can make it have the function of compliance movement,self-adjusting contact and collision avoidance.It can also reduce the secondary damage to the mechanical arm and environment when an accident occurs.Aiming at the application of SEA in mechanical arm,the main work of this thesis is arranged as follows:First of all,the structure of SEA is designed according to the size of the wrist of palletizing robot.In this thesis,the composition of SEA prototype and its working principle are introduced in detail.The torque measurement formula of SEA is derived.The performance indexes of SEA are given.And the main elements are analyzed by finite element analysis to ensure its reliability.At the same time,to ensure the correctness of the designed SEA prototype,the tests of PWM control,encoder reading and torque measurement are completed.In the study of SEA model,there are two output models of the motor,speed/position output and force output.So the speed/position source model and the force source model are respectively established according to the output form of the motor and the elastic element is simplified to rigid-damping system.Then the stability of two models are analyzed by using Nyquist Diagram and Bode Plot,researching the influence of stiffness,damping and load onstability.Secondly,SEA virtual prototype system is established using ADAMS and MATLAB simulation technology,and the SEA force tracking simulation experiments are completed in the virtual prototype system.For the application of SEA in mechanical arm,the design and simulation of mechanical arm zero force control system,double closed-loop PID position control system and mechanical arm flexibility control system are completed in the virtual prototype,considering the characteristic of flexibility of SEA.Finally,the experiment platform is built using Arduino UNO and PC in this thesis.Using physical experiments verifies the zero force control system,force tracking system and the flexibility control system,and the integration experiment of SEA and palletizing robot is completed.