Design of an underactuated grasper with adjustable compliance

Design of an underactuated grasper with adjustable compliance

Stavenuiter, R.A.J.

Herder, J.L. (mentor)
Birglen, L. (mentor)

Mechanical, Maritime and Materials Engineering

BioMechanical Engineering

BMD

2013-05-30

Underactuated graspers are known for their self-adaptability. The final configuration of the grasper in which it obtains a stable grasp relies on the static equilibrium of the grasper and object. Any external or inertial force that acts on the object disturbs this static equilibrium and causes a change in the configuration of the grasper. The self-adaptability therefore reduces the robustness against external perturbations. This thesis introduces the concept design of an underactuated grasper with the ability to adjust its level of self-adaptability by changing the rotational stiffness of an internal differential mechanism. By implementing a bi-stable mechanism the grasper is able to transfer from a compliant state to a stiff state once the actuator force overcomes a threshold value. Experimental validation of the concept design shows that the lateral compliance of the grasper in the stiff state is reduced by a factor of 7 compared to the compliant state. The lateral pull-out force of the grasper in the stiff state is increased by a factor of 1.9 compared to the compliant state. As a result a grasper was designed which uses the benefits of self-adaptability to grasp an object and increases its robustness once a stable grasp is obtained without the need of an additional actuator.

underactuated grasping

http://resolver.tudelft.nl/uuid:2d37a2d0-1da2-4649-a746-eda0118d93d4

2013-07-17

Student theses

master thesis

(c) 2013 Stavenuiter, R.A.J.