Maciej Pietrusinski

Design and control of a robotic lower extremity exoskeleton for gait rehabilitation

Design and control of an active knee rehabilitation orthotic system called ANdROS that was designed as a wearable and portable gait rehabilitation tool is presented. A corrective force field that reinforces a desired gait pattern is applied to the patients impaired leg around the knee joint via an impedance controlled exoskeleton. The impedance controller is synchronized with the patients walking phase which is estimated from the kinematic measurements of the healthy leg. The performance of the controller is evaluated through bench-testing.

Robotic Gait Rehabilitation Trainer

This paper presents the basic principle of operation, the mechanical design, and the control system of the Robotic Gait Rehabilitation (RGR) Trainer. This novel single-actuator mechatronic system targets secondary gait deviations affecting patterns of movement of the pelvis in stroke survivors. These deviations arise as compensatory movements associated with primary gait deviations, such as the lack of sufficient knee flexion during the swing phase of the gait cycle. Using an expanded impedance control strategy, the device generates a force field that affects the obliquity of the pelvis (rotation of the pelvis around the anteroposterior axis) via a lower body exoskeleton while the patient ambulates on a treadmill. Preliminary healthy human subject testing demonstrated that the RGR Trainer can effectively guide the pelvis in the frontal plane via force fields to alter pelvic obliquity.

Robotically generated force fields for stroke patient pelvic obliquity gait rehabilitation

The Robotic Gait Rehabilitation (RGR) Trainer, was designed and built to target secondary gait deviations in patients post - stroke. Using an impedance control strategy and a linear electromagnetic actuator, the device applies a force field to control pelvic obliquity through an orthopedic brace while the patient ambulates on treadmill. Healthy human subject testing confirmed efficacy of the method to impart significant gait restoration forces as a response to abnormal pelvic obliquity (hip hiking). This novel approach to application of force fields using endpoint impedance controlled linear actuators takes into account soft tissue compliance.

Design of human — Machine interface and altering of pelvic obliquity with RGR Trainer

The Robotic Gait Rehabilitation (RGR) Trainer targets secondary gait deviations in stroke survivors undergoing rehabilitation. Using an impedance control strategy and a linear electromagnetic actuator, the device generates a force field to control pelvic obliquity through a Human-Machine Interface (i.e. a lower body exoskeleton). Herein we describe the design of the RGR Trainer Human-Machine Interface (HMI) and we demonstrate the systems ability to alter the pattern of movement of the pelvis during gait in a healthy subject. Results are shown for experiments during which we induced hip-hiking — in healthy subjects. Our findings indicate that the RGR Trainer has the ability of affecting pelvic obliquity during gait. Furthermore, we provide preliminary evidence of short-term retention of the modified pelvic obliquity pattern induced by the RGR Trainer.

Design of a Gait Training device for control of pelvic obliquity

This paper presents the design and testing of a novel device for the control of pelvic obliquity during gait. The device, called the Robotic Gait Rehabilitation (RGR) Trainer, consists of a single actuator system designed to target secondary gait deviations, such as hip-hiking, affecting the movement of the pelvis. Secondary gait deviations affecting the pelvis are generated in response to primary gait deviations (e.g. limited knee flexion during the swing phase) in stroke survivors and contribute to the overall asymmetrical gait pattern often observed in these patients. The proposed device generates a force field able to affect the obliquity of the pelvis (i.e. the rotation of the pelvis around the anteroposterior axis) by using an impedance controlled single linear actuator acting on a hip orthosis. Tests showed that the RGR Trainer is able to induce changes in pelvic obliquity trajectories (hip-hiking) in healthy subjects. These results suggest that the RGR Trainer is suitable to test the hypothesis that has motivated our efforts toward developing the system, namely that addressing both primary and secondary gait deviations during robotic-assisted gait training may help promote a physiologically-sound gait behavior more effectively than when only primary deviations are addressed.

Healthy Subject Testing with the Robotic Gait Rehabilitation (RGR) Trainer

The Robotic Gait Rehabilitation (RGR) Trainer has been designed to address secondary gait deviations in stroke survivors undergoing rehabilitation. In this paper we describe the operating principle of the RGR Trainer and the systems ability to record the pelvic obliquity patterns (during normal gait and during hip hiking simulated by healthy subjects). Furthermore, we present results of experiment designed to teach new gait pattern in healthy subjects.

Triggering motor adaptations at the pelvis using the RGR trainer

The ability to generate motor adaptations in response to a perturbation is directly related to the capacity of a person to process the feedback related to the perturbation and to generate an adequate motor plan in response. In this work, we investigated the possibility to generate motor adaptations in response to perturbations in the pelvis trajectory in a pool of healthy subjects. Subjects experienced up- and downward force field perturbations at the pelvic area with and without visual feedback on the actual and desired pelvic trajectories. Results showed that it is possible to trigger a motor adaptation behavior while perturbing pelvis obliquity only in response to a downward pushing force field and in the presence of visual feedback, thus indicating a) that pelvic perturbations are not deemed as task relevant by the central nervous system while walking on a treadmill; b) that visual feedback can trigger adaptation to non-task relevant perturbations; c) that hip abductors and extensors cannot generate strong pelvis-dropping forces.