Research And Design Of The End-Effector Of An Apple-picking Robot

An end-effector was designed for an apple-picking robot. The end-effector consists of two parts:a four-fingered underactuated robot hand and a cutting instrument. The cutting instrument is made up of two sling blades. Both the robot hand and the sling blades are tendon-actuated. Using cables as tendons can separate the driving part and the operation part and lighten the weight of the distal phalanx of the manipulator, giving more options to choose driving motors.Firstly, the kinematic properties of the robot hand were analyzed. Through simulation and analysis, the relationships of the joint variables were established as well as the relationship between the joint variables and the tendon displacement. The joint variables are directly proportional to stiffness constant of the torsional springs and inversely proportional to the arms of the forces in tendon. The tendon displacement is linear with the joint variables.Secondly, the basic theoretical grasp analysis problems were analyzed and discussed and the model of the grasp was established serving for the theoretical basis of the stability of the robot hand.Thirdly, the distribution of the grasp forces was analyzed. Through simulation and analysis, the follow conclusion can be made:Under the same actuating force, the grasp-force of the tendon-actuated humanoid robot hand is related to the parameters of mechanism. The virtual grasp-force is determined by the length and thickness of the fingers. The distribution of grasp-force is determined by the lengthy proportions of the phalanges. The original angle between the fingers determines the radius range of the apples. As the radius of apples increases, the virtual grasp-force decreases. Frictions can homogenize the distribution of grasp-force as well as enlarge the virtual force.Finally, the machine system and control system were designed.