Gait Simulation via a 6-DOF Parallel Robot With Iterative Learning Control

Abstract

We have developed a robotic gait simulator (RGS) by leveraging a 6-degree of freedom parallel robot, with the goal of overcoming three significant challenges of gait simulation, including: 1) operating at near physiologically correct velocities; 2) inputting full scale ground reaction forces; and 3) simulating motion in all three planes (sagittal, coronal and transverse). The robot will eventually be employed with cadaveric specimens, but as a means of exploring the capability of the system, we have first used it with a prosthetic foot. Gait data were recorded from one transtibial amputee using a motion analysis system and force plate. Using the same prosthetic foot as the subject, the RGS accurately reproduced the recorded kinematics and kinetics and the appropriate vertical ground reaction force was realized with a proportional iterative learning controller. After six gait iterations the controller reduced the root mean square (RMS) error between the simulated and in situ; vertical ground reaction force to 35 N during a 1.5 s simulation of the stance phase of gait with a prosthetic foot. This paper addresses the design, methodology and validation of the novel RGS.

Upper Limb Electrical Stimulation Using Input-Output Linearization and Iterative Learning Control

“…Iterative learning control (ILC) is another leading approach, and has exploited the repetitive nature of the rehabilitation process, where patients attempt the same task multiple times in order to promote re-learning. ILC sequentially improves accuracy by using data from previous attempts to adjust the FES supplied during the next execution of the task, and has been successfully used by several groups to assist movement in the lower limb [17], [18], [19], [20]. This paper focuses on the upper limb, and combines inputoutput linearization with a general linear ILC form that has been employed in three sets of clinical trials [21] during which the tracking accuracy provided by ILC translated into statistically significant results across a range of outcome measures [22], [23].…”

Foot bone kinematics as measured in a cadaveric robotic gait simulator

“…While these simulators are valuable tools in understanding foot bony motion, their accuracy has been affected by the following: non-physiologic ground reaction forces (GRFs) [5], simplified tibial kinematics [5,8,9], low velocity of simulation [8,9], low vertical GRF (vGRF) magnitude [5,8,9], exclusion of bones [9], and technical, rather than anatomical, based coordinate systems [5,8,9]. Our group has developed a cadaveric gait simulator (i.e., the robotic gait simulator or RGS) that has begun to address these issues [10][11][12], with the intent to provide a more accurate and realistic description of foot kinematics during walking. The aim of this work was to provide a description of the bony motion of the foot during gait and present a methodology (the RGS) that addresses many of the limitations associated with dynamic in vitro foot and ankle models of gait.…”

Novel Method to Evaluate Angular Stiffness of Prosthetic Feet From Linear Compression Tests

“…Force, displacement, and center of pressure (COP) measurements of 9-different foot configurations were tested on a force plate (Kistler Instrument Corp., Amherst, NY) that was mounted to a 6-degree of freedom (DOF) parallel robot (Mikrolar Inc., Hampton, NH) [9]. The test foot was aligned with the force plate such that the pylon was normal to the surface and the foot was at 0 deg of internal-external rotation with respect to the force plate coordinate system when the robot was in its home position (Fig.…”