Hybrid Force–Velocity Sliding Mode Control of a Prosthetic Hand

Abstract

Four different methods of hand prosthesis control are developed and examined experimentally. Open-loop control is shown to offer the least sensitivity when manipulating objects. Force feedback substantially improves upon open-loop control. However, it is shown that the inclusion of velocity and/or position feedback in a hybrid force-velocity control scheme can further improve the functionality of hand prostheses. Experimental results indicate that the sliding mode controller with force, position, and velocity feedback is less prone to unwanted force overshoot when initially grasping objects than the other controllers.

Building the Ninapro database: A resource for the biorobotics community

“…While the classifier is used to understand which hand or grasp posture is desired (e.g., fully stretched hand, power grasp, pointing index), the regressor predicts the force required in the case of a grasping posture. The approaches presented so far in the literature use various techniques for preprocessing the data [2], [3], classifying the postures [3]- [5] and predicting the associated force [3], [6], [7]; despite the differences, all these studies share a common validation procedure, in which experiments are conducted on a proprietary database containing between five and ten intact subjects and amputees, which are executing up to ten different grasp actions, enacting static hand postures or moving their fingers and wrist. (We will from now on collectively denote these actions movements of interest; see section I-A for a more detailed review).…”

Force control of an underactuated prosthetic hand based on sliding mode with exponential reaching law

“…Sliding mode controllers based on constant reaching law are implemented for a four-link prosthetic hand [13,14], the control method with constant reaching law is fast to response because the rigidity of this prosthetic hand is large. However, the underactuated prosthetic hand has complicated mechanism, flexible joint and cable transmission, this generally introduce a large friction force that degrades the control response [15].So, sliding mode with exponential reaching law which has quick response to system is fit for underactuated prosthetic hand [16].…”

A Weight Estimation Method for Prosthetic Hand

“…Based on the Stribeck friction model [11], the dynamic behavior of the friction at low velocity is, For simplicity, a first order Taylor expansion is used to approximate this model because it is nonlinear,…”