Bioinspired Cable-Driven Actuation System for Wearable Robotic Devices: Design, Control, and Characterization

Abstract

Wearable robotic devices interact with human by applying assistive force in parallel with muscle-tendon systems. Designing actuations in mimicking the natural activation patterns of human muscles is a promising way to optimize the performance of wearable robots. In this paper, we propose a bio-inspired cable-driven actuation system capable of providing anisometric contractions (including concentric and eccentric contraction) assistance or nearly acting as a transparent device in an efficient manner. A novel clutch-spring mechanism is employed to accomplish switches between assistive modes and the transparent mode. Corresponding control strategies coordinating with the mechanical design were presented and described in detail. Multiple evaluations were conducted on a test bench to characterize the system performance. The closed-loop bandwidth of the system running concentric assistance control was 18.2 Hz. The R-squared values of linear fitting under eccentric assistance control were above 0.99. The engagement time of the proposed clutch was about 90 ms. Applying the actuation to an ankle exoskeleton, multiple walking experiments with electromyography measurement were performed on five subjects to show its application potential in existing wearable robots. Experimental results revealed that the proposed design could reduce soleus muscle activity by 27.32% compared with normal walking. This study highlights the importance of functional bionic design in human-assistance-related devices and introduces a general actuation system that could be directly applied to existing cabledriven wearable robots.

Design and Analysis of a Symmetric Joint Module for a Modular Wire-Actuated Robotic Arm with Symmetric Variable-Stiffness Units

“…Writing xx  • = as the angular velocity of the coordinate system {M} relative to the coordinate system {S} about the X axis of {S}, then (11) could be written as:…”

“…Comparing with the rigid robots, wire-actuated robots have the advantages of low inertia, large workspace, high safety and adaptability. Because of these advantages, the wire-actuated robots are applied widely in many fields, such as lifting and positioning [3,4], detection and maintenance [5][6][7], wearable rehabilitation and assistance [8][9][10][11][12][13], medical surgery [14][15][16], soft robot arm and hand [17][18][19][20], bionic robot [21]. Researchers have 2 designed different wire-actuated robots and carry out a lot of research works, such as kinematics and statics analysis [22][23][24][25][26], workspace analysis [27,28], wire tension analysis [29], stiffness analysis [30], dynamics analysis [31,32], path and trajectory planning [33][34][35], motion and compliance control [36][37][38][39][40] and so on.…”

Soft Pumps: Catalysts for Advancing Fluid‐Driven Soft Robots

“…Soft actuators are essential components in soft robotics. Various actuation mechanisms such as fluid‐driven, [ 12,13 ] dielectric elastomer actuation (DEA), [ 14 ] shape memory alloys (SMAs), [ 15 ] magnetic‐driven, [ 16 ] and cable‐driven mechanisms [ 17 ] have been extensively explored. Among them, fluid‐driven soft robots have emerged as one of the most popular choices for soft robotics.…”