Design Of A 3D-printable Underactuated Hand

The aim of this assignment is to design,an underactuated robot gripper.The primary objective t is to create a cheap and easy-to-build gripper but polyvalent and easy-to-control at the same time.The gripper is devised to be built in the university using 3D printing technology and cheap components.Thus,following a contrastive analyse of diverse grippers,the underactuated gripper has been selected as the most suitable option.In terms of the anatomy of the hand,the assessment of possibilities leads to a 4-finger-hand design with two phalanges per finger.Each of the fingers and phalanges was actuated by tendons driven by a unique servomotor.This configuration is a compromise between grasp stability,adaptability to the object and hand complexity.Despite using a single servomotor,each finger can move independently from the others to grasp diverse objects through the underactuation principle.For the design of an underactuated hand it is very important to accurately calculate the optimal dimensions of the palm and fingers and the transmission ratio between phalanges.These parameters will determine the performance of the hand and the grasp type.The grasp type refers to the way in which the object is held,once equilibrium between the object and the grasper is achieved.The name of the different grasp types comes from the number of contact points between a cylindrical object and a 2-finger hand and it can go from two points(the distal phalanges)to 5 points(all the phalanges and the palm).Important was also to optimize the pulley system of the fingers.An optimum pulley system reduces the internal forces on the phalanges.This is important because the phalanges are going to be 3D printed in a low-resistance material.For this task,they both the influence of the pulleys radius and its position were studied and the forces supported by the phalanges were simulated with different pulley designs.The final parts were designed according to various criteria,such as the reduction of the number of parts making them multipurpose,making easy to print parts that need the minimum number of support structures,resistance,ease of assembly and security for the operator.The non-printed materials are cheap and easy to obtain and,besides the 3D printer,all necessary tools are basic.After all the calculations and simulations and after building a prototype,it can be concluded that the hand complies the objectives.The hand is therefore fully prepared to be used in research environments when an adaptative griper is required with a small budget.