Functional Evaluation of a Force Sensor-Controlled Upper-Limb Power-Assisted Exoskeleton with High Backdrivability

Abstract

A power-assisted exoskeleton should be capable of reducing the burden on the wearer’s body or rendering his or her work improved and efficient. More specifically, the exoskeleton should be easy to wear, be simple to use, and provide power assistance without hindering the wearer’s movement. Therefore, it is necessary to evaluate the backdrivability, range of motion, and power-assist capability of such an exoskeleton. This evaluation identifies the pros and cons of the exoskeleton, and it serves as the basis for its subsequent development. In this study, a lightweight upper-limb power-assisted exoskeleton with high backdrivability was developed. Moreover, a motion capture system was adopted to measure and analyze the workspace of the wearer’s upper limb after the exoskeleton was worn. The results were used to evaluate the exoskeleton’s ability to support the wearer’s movement. Furthermore, a small and compact three-axis force sensor was used for power assistance, and the effect of the power assistance was evaluated by means of measuring the wearer’s surface electromyography, force, and joint angle signals. Overall, the study showed that the exoskeleton could achieve power assistance and did not affect the wearer’s movements.

Methodologies for evaluating exoskeletons with industrial applications

“…Other analyses were more seldomly applied. This includes time impacts on workplaces [Dahmen and Constantinescu 2018], the number of executed errors (e.g., with a detection ring [Alabdulkarim and Nussbaum 2019a]), the fine motor skills with a pegboard [Madinei et al 2020a], applied forces (e.g., with a contact pressure mat [Huysamen et al 2018b], load cell [Liu et al 2020], dynamometer [Li et al 2018a], force plate [Maurice et al 2020]), metabolic costs (e.g., with ergospirometry [Baltrusch et al 2019], oxygen consumption [Junius et al 2018], heart rate [Maurice et al 2020], blood lactate concentration [Galle et al 2014], blood oxygenation [Gams et al 2013], minute ventilation [Gams et al 2013]), individual working speeds (e.g., walking on a treadmill [Baltrusch et al 2019]), task execution with maximum acceptable working frequency [Alabdulkarim and Nussbaum 2019a]), influences on the work load with sample independent data (e.g., from a humanoid testing machine [Nabeshima et al 2018, Ito et al 2018), or analysis of system's motion synchronicity and cycle stability with a joint simulator [Shamaei et al 2014]. Godwin et al [2009] and Lotz et al [2009] applied a testing machine assessing the human's maximum remaining strength after exhausting tasks with or without exoskeletal support.…”

Home-Based Robotic Upper Limbs Cardiac Telerehabilitation System

“…The patient home-based telerehabilitation system consists of a commercially available cobot with two force sensors (six-axis force sensors SRI M3715C and SRI M3713C) and a custom handlebar. The cobot is composed by one robot arm, one robot controller, a touchpad, and a pre-installed application called “PolyScope.” The cobot arm is a 6-DoF kinematic equipment that could satisfy all the mobility criteria of a human arm rehabilitation (5 DoFs) [ 31 ]. Accessing the cobot arm’s joint velocities and locations in real time is a breeze with the help of the robot’s in-built features [ 32 ].…”

A Novel Passive Shoulder Exoskeleton Using Link Chains and Magnetic Spring Joints

“…However, these approaches have limitations because each wearer has a different body size, device wearing position, and GH joint movement profile. In this study, an experimental approach is chosen to enhance the objectivity of shoulder ROM assessment before and after wearing the device [34]. To evaluate the ROM of the proposed exoskeleton, a visual examination of an adult male (age: 27 years, height: 168 cm, weight: 81 kg, upper arm: 20 cm, forearm: 37 cm) was performed.…”