Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
A novel design of robotic hand with linear motors
Submission Author:
Daniel Pascotto Costa , SP
Co-Authors:
Daniel Pascotto Costa, Chi Nan Pai
Presenter: Daniel Pascotto Costa
doi://10.26678/ABCM.COBEM2021.COB2021-0570
Abstract
Human hand, with a total of 27 degrees of freedom (DOFs), is capable of high levels of dexterity and precision of the movement. Development of a robotic hand with similar capability is a very challenging task that has been pursued by several groups, with little success. One of the biggest problems is the use of a small number of rotary motors and wires as actuation system. This solution tends to result in under-actuated mechanisms with lack of precision in the movement due to backlash, in addition to limited dexterity of the movement due to the small number of actuators. On the other hand, linear motors generally provide a higher output, but their use in robotic arms is not commonly explored. In this work, we propose a design of a robotic hand, driven by a total of 13 linear motors. By analyzing the common movements of the human hand, we chose to replicate, in our robotic hand, the movements of flexion and extension of proximal phalanges of all five fingers; flexion and extension of middle phalanges of all fingers except thumb; adduction and abduction of index finger, ring finger and pinky; and opposition of the thumb. The mechanisms were designed in such a way that minimizes the backlash of the movements, providing a better control of the movements of the fingers. Besides the usual linear position sensors and current sensors, several pressure sensors were also distributed throughout the hand in strategic places to provide feedback information for the control system. By using a computer aided design software to simulate the movements of our robotic hand, one can see that the chosen movements can be performed without interference, and the movements of cylindrical grasp and fine pinch are comparable to the ones performed by a human hand. The estimated range of motion and the output forces of the motors are also adequate, which prove that our design achieved the desired purpose. Furthermore, although only a total of 13 linear motors were used, which is fewer than the total DOFs of the hand, it is enough to perform all of the common movements of the hand. This is because several DOFs are actually not used independently, such as the sole flexion of the distal phalanges of the fingers. Therefore, our design can perform all the necessary movements of the human hand.
Keywords
Robotic hand, Linear motor, biomimetic, Biomechanic
