Force and motion control of a tendon-driven hand exoskeleton actuated by shape memory alloys

Abstract

Purpose

Many people suffer from injuries related to their hand. This research aims to focus on the improvement of the previously developed smart glove by using position and force control algorithms. The new smart glove may be used for both physiotherapy and assistance.

Design/methodology/approach

The proposed robot uses shape memory alloy (SMA) actuators coupled to an under-actuated tendon-driven mechanism. The proposed device, which is presented as a wearable glove attached to an actuation module, is capable of exerting extremely high forces to grasp objects in various hand configurations. The device’s performance is studied in physiotherapy and object manipulation tasks. In the physiotherapy mode, hand motion frequency is controlled, whereas the grasping force is controlled in the object manipulation mode. To simulate the proposed system behavior, the kinematic and dynamic equations of the proposed system have been derived.

Findings

The achieved results verify that the system is suitable to be used as part of a rehabilitation device in which it can flex and extend fingers with accurate trajectories and grasp objects efficiently. Specifically, it will be shown that using six SMA wires with the diameter of 0.25 mm, the proposed robot can provide 45 N gripping force for the patients.

Originality/value

The proposed robot uses SMA actuators and an under-actuated tendon-driven mechanism. The resulted robotic system, which is presented as a wearable glove attached to an actuation module, is capable of exerting extremely high force levels to grasp objects in various hand configurations. It is shown that the motion and exerted force of the robot may be controlled effectively in practice.

Citation

Kazeminasab, S., Hadi, A., Alipour, K. and Elahinia, M. (2019), "Force and motion control of a tendon-driven hand exoskeleton actuated by shape memory alloys", Industrial Robot, Vol. 45 No. 5, pp. 623-633. https://doi.org/10.1108/IR-01-2018-0020