Design and optimization of a three-fingered robot hand

Abstract

Humanoid robots have proven to be very useful and could revolutionize the way humans live. Knowing human anatomy and behaviour helps improve a robotic mechanisms ability to perform human tasks. The following thesis introduces the concept of a threefingered robot hand and its driving mechanism. The hand includes two fingers and a thumb. Using the concept of “an under actuated system”, each finger consists of three revolute joints which are driven by two actuators and tooth belt transmission system. The thumb has two joints but only one joint is active and actuated by one motor. The passive joint is designed to set the initial position of the thumb on the piano key if necessary. Required angle of rotation for each joint has been calculated through Inverse Kinematics. Once the fingertip presses the piano key, it should apply 1N force to play a note. Force Sensing Resistors at each finger tip, as a control method, are introduced to the system to accurately measure the amount of applied force from the finger tip on the key and increase the angle of rotation of the motor if needed. Stress and deformation of the joints have been studied through Finite Element Analysis. A prototype model, consisting of a single finger was built to better understanding the functionality of the concept. Analysis of this model, led to necessary modification of the transmission system and some design revisions to each link. Genetic Algorithm using MATLAB was used to optimize the performance Index of a finger. Finally the hand assembly including all the components and driving mechanism was constructed and experimented in the playing mode.