An Analysis for a Mini robot gripper using SMA Springs

The development of a compact and lightweight gripper suitable for a mini mobile robot for field applications poses many challenges. This is because conventional gripper actuation methods may be infeasible due to their size, weight and power requirements. This study focuses on the development of a suitable linkage mechanism for such a mini gripper, using two different actuation methods. The first design investigates the use of shape memory alloy (SMA) springs as a newer method for the gripper actuation. For comparison, the second design is developed using a more conventional, servomotor-based actuation. The design of the SMA springs used in the first gripper, and the kinematic analysis for both gripper designs, are presented. Prototypes of both designs were built and tested, and the results are also shown. Additionally, an accuracy analysis involving the gripper mechanism's tolerances and clearances is developed for both grippers, and a tolerance allocation technique to facilitate such gripper designs is also presented. The study shows that SMA spring actuated grippers hold promise for certain applications and should be considered in the design of mini mobile robot devices.