Acceleration-based transparency control framework for wearable robots

Abstract

Abstract-To render a wearable robot imperceptible to a user is a very challenging control task. The constant and intrinsic interaction between robot and human, and persondependent behaviours are the main difficulties when designing such cooperative control. In this contribution we introduce and discuss a novel and promising transparency control framework. The foundation of the framework is to measure the acceleration of the human limbs and to exploit this measurement to generate feedforward control commands by using a rigid body model of the robot. The framework includes also an acceleration feedback controller and a state estimator to enhance the overall performance. We present a simplified stability analysis with different feedback controllers and preliminary experimental data that demonstrate the potential of the proposed method in reducing interaction forces and mimicking human motions.

Modeling and Loop Shaping of Single-Joint Amplification Exoskeleton with Contact Sensing and Series Elastic Actuation

“…And one exoskeleton has used acceleration to reduce the apparent inertia of the operator (rather than merely reducing the apparent mass of the exoskeleton) [21]. Acceleration has been proposed as a complete framework for exoskeleton control [22]. But successful as this strategy is, it cannot aid in amplification objectives-since the environment is generally not known in advance.…”

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

“…However, to improve the output torque of wearable robots, the reducer with a high reduction ratio is generally employed in the actuation design, which will deteriorate the back-drivability of the robotic system [16]. How to achieve system transparency effectively is a big challenge in implementation [17,18].…”