Implementation of a user_modulated stiffness control for an embedded end effector device

• Main Author: Thiagarajan, Tevaryan
• Other Authors: Lorenzo Masia
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/72288
• Institution: Nanyang Technological University

This report presents the development of an embedded control system that can modulate and control the position and stiffness of an end-effector device. The modulation of position and stiffness of the device is done in real-time, and interfaced using myoelectric signals of the user. The end effector mimics characteristics of a single degree of freedom joint in the human upper arm, more specifically the wrist joint. Human movement is quite complicated, and modulation of stiffness is essential for safe interaction with the environment and successfully performing activities of daily living. We modulate stiffness depending on the task we perform; to perform a fast movement, we do not stiffen up our limbs while we stiffen up our limbs while resisting a change in motion or opposing an oncoming force. The aim of this project is to be able to transfer the stiffness and position of the user to an end-effector device in real-time, with implications in tele-manipulation and prosthesis. There are many studies that have worked on user-modulated position and stiffness control, but the main purpose of this project is to develop a control system that is embedded, cost-effective and portable. Our device comprises of a signal acquisition system and a signal processing system and aims to eliminate the need for a bulky and sophisticated equipment. The signal acquiring system used in this project is the Myo-Armband, while the signal processing units are the Raspberry-Pi and the Arduino. The end effector is moved by a Maxon motor which is driven by an Escon motor driver. All the control components stated above are modular and are light weight. This makes the control system portable. This report was done with the goal of laying the ground-work to implement these control systems unto a soft-exoskeleton or prosthetics in the future. The end-product of this project is a portable control system that can manipulate an end effector with the ability of it adjusting to a wide variety of stiffness conditions done by the user.