Robot Electric Gripper With 4 DOF And 8 Joint Of 3 Finger

With the continuous expansion of robot application,requirements for robot grasping ability are more challengeable than past.As the end-effector for robot to interact with environment,the research of the multi-fingered gripper is very important to improve the work ability and intelligence level of robot.This paper reviews the literature of multi-fingered gripper,an electric gripper with four degrees of freedom,eight joints and three fingers is designed based on the domestic and international research about electric gripper.At the same time,the control software of the host computer is developed.Acontrol strategy is used to realize the flexible grasping of the electric gripper.The main research work is as follows:(1)This paper presents a four degrees of freedom,eight joints and three fingers robot electric gripper design,inwhich a motor drives the two rotating fingers reversemoving through the steering mechanism so as to make fingers relocated in space;and another motor achieves separate control to three fingers with an electromagnet and a clutch mechanism.SolidWorks software is used to design the mechanical structure in detail,including the design of finger,palm,base,clutch mechanism,steering mechanism and rope coupling mechanism.In addition,the working principle of rope coupling mechanism and clutch mechanism is further analyzed by the three-dimensional model.(2)An appropriate control system is designed for the mechanical structure of the robot electric gripper,which includes the hardware selection and the software design of the host computer.The core hardware mainly includes motor,reducer,encoder,electromagnet,motor control module,three-way relay module,etc.LabVIEW is used to write the host computer con-trol software which has the functions of trajectory planning,data display and record,parameter setting,motor control,electromagnet control and so on.The software is mainly composed of manual debugging,automatic operation and parameter setting.(3)This paper analyzed kinematics of the robot electric gripper.According to the Denavit-Hartenberg theory to establish the coordinate system and D-H parameters table.By using the coordinate transformation matrix,the mapping relationship between finger tip coordinates and palm base coordinates is established so that the finger tip position equation is deduced.Then MATLAB software is used to simulate the working space of electric gripper.The kinematics equation of electric gripper provides the theoretical basis for the control of the finger.(4)A control strategy which divided into three control stages is proposed.The three control stages are position control of joint space,position control in Cartesian space and force control in the grasping phase.Among them,the position control of joint space use the method of five polynomial function,and the position control of Descartes space is based on the T type velocity function method,and the PID algorithm is adopted for force control.At last,the single finger force feedback experiment and the grasping of the typical shape object experiment are carried out for electric gripper.The results show that the electric gripper meets the design requirements.