CAREER: Modeling Time Invariances in Human Motor Coordination for Robot-Assisted Rehabilitation

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

Robot-assisted rehabilitation can enhance and speed motor control recovery following brain injury such as stroke. Most existing rehabilitation approaches and modeling work supporting them focus primarily on the forces required to generate controlled movements, in effect deemphasizing planning that occurs at a kinematic level. A thorough understanding of the role of kinematics in coordination is needed to help diagnose the level at which deficiencies lie, and then focus treatment at that level. In this project, the PI will formulate and experimentally validate unified, coherent models of human motor coordination based on a foundational time-invariant, kinematic mapping between the output space and the control space. Inspired by curvature theory, which is traditionally applied to mechanism synthesis, such a mapping provides an elegant description of motion. With this novel approach, the PI will seek to demonstrate that decoupling the kinematic geometry from the time-based trajectory tracking of arm motion leads to a compact internal model of path planning consistent with experimental data. The work will further demonstrate that a similarly compact internal dynamic model provides an additional layer for an efficient formulation of motor control. The internal kinematic and dynamic models to be developed will enable investigation of optimization mechanisms at the kinematic level, the dynamic level, and through mutual interaction of the two. In order to experimentally validate this model, the PI will develop an actuated, but back-drivable, planar x-y table that has uniform apparent endpoint inertia throughout its workspace. This device will both enable the model validation experiments and serve as a first prototype for a new robot-assisted rehabilitation device that can be used to clinically leverage the knowledge gained from the modeling effort. The PI will collaborate with colleagues in his institution's Physical Therapy Division and Physical Medicine and Rehabilitation Department to develop and evaluate new diagnostic and rehabilitation techniques that implement the new device based on the findings. Broader Impacts: Robot-assisted rehabilitation is likely to have an increasingly significant impact on society as health care costs rise and the number of strokes increases with population aging. Grounded in understanding human motor coordination, this research will impact the fields of locomotion, neurally controlled prosthetics, digital human modeling, and robot control. The investigator will integrate this research into his educational activities with two foci: increasing student understanding of the significance of kinematics and dynamics in human motor coordination; and enhancing student ability to internally visualize physical movement in mechanical systems. These activities will involve modifications to a required undergraduate kinematics course, an elective undergraduate product design course, and two graduate kinematics courses to incorporate the results of the research. Additionally, a seminar course for students from all academic units will be developed to more broadly disseminate the work. In conjunction with four other faculty in the Ohio State College of Engineering, the PI will organize a weeklong engineering summer camp for women and minority high school students. The PI will create two modules for the camp: one related to human motor coordination in which the students will conduct experiments using the x-y table developed in the project; and one related to visualization of motion in mechanical systems.