TY - JOUR T1 - The SE-AssessWrist for robot-aided assessment of wrist stiffness and range of motion: Development and experimental validation JF - Journal of Rehabilitation and Assistive Technologies Engineering Y1 - 2021 A1 - Andrew Erwin A1 - Craig G McDonald A1 - Nicholas Moser A1 - Marcia K O’Malley AB -

IntroductionPhysical human-robot interaction offers a compelling platform for assessing recovery from neurological injury; however, robots currently used for assessment have typically been designed for the requirements of rehabilitation, not assessment. In this work, we present the design, control, and experimental validation of the SE-AssessWrist, which extends the capabilities of prior robotic devices to include complete wrist range of motion assessment in addition to stiffness evaluation.MethodsThe SE-AssessWrist uses a Bowden cable-based transmission in conjunction with series elastic actuation to increase device range of motion while not sacrificing torque output. Experimental validation of robot-aided wrist range of motion and stiffness assessment was carried out with five able-bodied individuals.ResultsThe SE-AssessWrist achieves the desired maximum wrist range of motion, while having sufficient position and zero force control performance for wrist biomechanical assessment. Measurements of two-degree-of-freedom wrist range of motion and stiffness envelopes revealed that the axis of greatest range of motion and least stiffness were oblique to the conventional anatomical axes, and approximately parallel to each other.ConclusionsSuch an assessment could be beneficial in the clinic, where standard clinical measures of recovery after neurological injury are subjective, labor intensive, and graded on an ordinal scale.

VL - 8 UR - https://doi.org/10.1177/2055668320985774 ER - TY - Generic T1 - A Bowden Cable-Based Series Elastic Actuation Module for Assessing the Human Wrist T2 - ASME Dynamic Systems and Controls Conference Y1 - 2018 A1 - Andrew Erwin A1 - Nick Moser A1 - Craig. G. McDonald A1 - Marcia K. O'Malley JF - ASME Dynamic Systems and Controls Conference PB - ASME CY - Atlanta, GA ER - TY - JOUR T1 - A Time-Domain Approach To Control Of Series Elastic Actuators: Adaptive Torque And Passivity-Based Impedance Control JF - IEEE/ASME Transactions on Mechatronics Y1 - 2016 A1 - Dylan P. Losey A1 - Andrew Erwin A1 - Craig G. McDonald A1 - Fabrizio Sergi A1 - Marcia K. O'Malley AB -

Robots are increasingly designed to physically interact with humans in unstructured environments, and as such must operate both accurately and safely. Leveraging compliant actuation, typically in the form of series elastic actuators (SEAs), can guarantee this required level of safety. To date, a number of frequency-domain techniques have been proposed which yield effective SEA torque and impedance control; however, these methods are accompanied by undesirable stability constraints. In this paper, we instead focus on a time-domain approach to the control of SEAs, and adapt two existing control techniques for SEA platforms. First, a model reference adaptive controller is developed, which requires no prior knowledge of system parameters and can specify desired closed-loop torque characteristics. Second, the time-domain passivity approach is modified to control desired impedances in a manner that temporarily allows the SEA to passively render impedances greater than the actuator's intrinsic stiffness. This approach also provides conditions for passivity when augmenting any stable SEA torque controller with an arbitrary impedance. The resultant techniques are experimentally validated on a custom prototype SEA.

VL - 21 UR - http://ieeexplore.ieee.org/abstract/document/7457670/ ER - TY - JOUR T1 - Interaction control capabilities of an MR-compatible compliant actuator for wrist sensorimotor protocols during fMRI JF - IEEE/ASME Transactions on Mechatronics Y1 - 2015 A1 - Fabrizio Sergi A1 - Andrew Erwin A1 - Marcia K. O'Malley KW - compliant actuators. KW - Force control KW - functional MRI (fMRI) KW - MR-compatible robotics AB -

This paper describes the mechatronic design and characterization of a novel MR-compatible actuation system designed for a parallel force-feedback exoskeleton for measurement and/or assistance of wrist pointing movements during functional neuroimaging. The developed actuator is based on the interposition of custom compliant elements in series between a non-backdrivable MR-compatible ultrasonic piezoelectric motor and the actuator output. The inclusion of physical compliance allows estimation of interaction force, enabling force-feedback control and stable rendering of a wide range of haptic environments during continuous scanning. Through accurate inner-loop

velocity compensation and force-feedback control, the actuator is capable of displaying both a low-impedance, subject-in-charge mode, and a high stiffness mode. These modes enable the execution of shared haptic protocols during continuous fMRI. 

The detailed experimental characterization of the actuation system is presented, including a backdrivability analysis, demonstrating an achievable impedance range of 22 dB, within a bandwidth of 4 Hz (for low stiffness). The stiffness control bandwidth depends on the specific value of stiffness: a bandwidth of 4 Hz is achieved at low stiffness (10% of the physical springs stiffness), while 8 Hz is demonstrated at higher stiffness. Moreover, coupled stability is demonstrated also for stiffness values substantially (25%) higher than the physical stiffness of the spring. Finally, compatibility tests conducted in a 3T scanner are presented, validating the potential of inclusion of the actuator in an exoskeleton system for support of wrist movements during continuous MR scanning, without significant reduction in image quality.

VL - 20 ER - TY - Generic T1 - Compliant force-feedback actuation for accurate robot-mediated sensorimotor interaction protocols during fMRI T2 - International Conference on Biomedical Robotics and Biomechatronics (BioRob) Y1 - 2014 A1 - Fabrizio Sergi A1 - Andrew Erwin A1 - Brian Cera A1 - Marcia K. O'Malley JF - International Conference on Biomedical Robotics and Biomechatronics (BioRob) PB - IEEE ER - TY - Generic T1 - Interaction control for rehabilitation robotics via a low-cost force sensing handle T2 - 6th Annual ASME Dynamic Systems and Controls Conference Y1 - 2013 A1 - Andrew Erwin A1 - Fabrizio Sergi A1 - Vinay Chawda A1 - Marcia K. O'Malley JF - 6th Annual ASME Dynamic Systems and Controls Conference CY - Palo Alto, CA ER - TY - Generic T1 - The RiceWrist Grip: A Means to Measure Grip Strength of Patients Using the RiceWrist Y1 - 2012 A1 - Ryan Quincy A1 - Andrew Erwin A1 - A.U. Pehlivan A1 - Yozbatiran, Nuray A1 - Gerard Francisco A1 - Marcia K. O'Malley ER -