Research On Three-fingered Underactuated Manipulator

Science and technology are advancing rapidly,including robotics.As the end-effector of the robot system,the manipulator has become a hot research field in recent years.Since the shape,size and material of the grabbed object are very different,the manipulator must have a strong adaptive ability and grasp the reliability.Therefore,the adaptive ability and grasping stability of the manipulator is the key to the research.This paper designed a manipulator based on the underactuation principle.By applying the underactuation principle to the manipulator,the manipulator can grasp the object with the lowest cost and the simplest control.In addition,in view of the limited working range caused by the fixed position of the finger of the manipulator at present,this paper adds the method of rotating the palm to solve this problem.The underactuated manipulator has a fixed base finger,two rotatable base fingers with three fingers and a palm base.By adjusting the relative position of fingers through the gear set,it can grasp objects of various shapes through different grasping methods.Each finger has three knuckles and is controlled by a drive.The manipulator has ten degrees of freedom and four drives.Based on the design and application of the manipulator,the kinematics and statics of the underactuated manipulator were theoretically analyzed,and the key structural parameters affecting the working performance of the manipulator were obtained,which provided the theoretical basis for optimization.Aiming at two phenomena which may lead to the instability of the manipulator grasping,"ejection" and the local degrees of freedom of the object when enveloping grasping is completed are analyzed and discussed.To avoid "ejection" the finger size was optimized.In order to avoid grabbing instability caused by local degrees of freedom,starting from the finger contact mode,the contact point during grasping was increased,and the flexible fingertip was used to replace the rigid fingertip,which enhanced the stability of grasping and anti-interference ability.Next,the three-dimensional solid model is established,the kinematics and dynamics simulation are carried out in ADAMS.For the flexible body in the structure,ANSYS and ADAMS are used for joint simulation to conduct vibration and impact test.The adaptive capability and stability of underactuated manipulator are verified by simulation.The underactuated manipulator prototype is made by 3D printing technology,and the experimental platform is built to test its grasping performance.In order to verify the adaptive ability of practical work,different experiments are carried out on the common objects in life,which have good practical work effect and achieve the design goal.