ZeroG: Overground gait and balance training system

Abstract

Abstract-A new overground body-weight support system called ZeroG has been developed that allows patients with severe gait impairments to practice gait and balance activities in a safe, controlled manner. The unloading system is capable of providing up to 300 lb of static support and 150 lb of dynamic (or constant force) support using a custom-series elastic actuator. The unloading system is mounted to a driven trolley, which rides along an overhead rail. We evaluated the performance of ZeroG's unloading system, as well as the trolley tracking system, using benchtop and human-subject testing. Average root-mean-square and peak errors in unloading were 2.2 and 7.2 percent, respectively, over the range of forces tested while trolley tracking errors were less than 3 degrees, indicating the system was able to maintain its position above the subject. We believe training with ZeroG will allow patients to practice activities that are critical to achieving functional independence at home and in the community.

Muscle activation during body weight-supported locomotion while using the ZeroG

“…In agreement with Hidler et al [8], increasing BWS decreased muscular demand of the lower limbs during the walking trials, thereby decreasing the intensity of the task. In the present study, lower-limb hip flexors and ankle plantarflexors were more affected by BWS (RF > MG) than ankle dorsiflexors and hip extensors (TA > BF).…”

“…Body weight was taken using an electronic scale after electrode and footswitch attachment was complete and with subjects wearing their shoes during the measurement. Finally, participants were fitted to the appropriate size ZeroG harness and were given the opportunity to practice walking at all of the various levels of BWS (0/20/40/60/80%); the ZeroG BWS system has been described in detail previously [8].…”

“…The newly developed ZeroG system (Aretech LLC; Ashburn, Virginia), created by Hidler et al, attempts to provide this dynamic BWS through the use of a custom-series elastic actuator during overground walking and balance training (Figure 1) [8]. It has been suggested that more natural ground reaction forces and gait characteristics can be achieved through the use of dynamic BWS [8]. To date, no study has investigated the effects of BWS on muscle activation patterns during walking using the ZeroG.…”

The road ahead for rehabilitation robotics

“…We are hopeful that this special issue of the Journal of Rehabilitation Research and Development dedicated to rehabilitation robotics will stimulate discussion and thought on these important questions. Understanding the future of rehabilitation robotics is quite complex, because we must first answer a number of related questions. For example, (1) What is the goal of the robot? (2) What are the barriers to the clinical acceptance of robotic devices in rehabilitation?…”

“…For example, attempting overground gait and balance training in a patient with both heavy weight and low function is difficult and unsafe for the average therapist. Devices such as ZeroG (Hidler et al [1]) can alleviate a portion of the patient's body weight to compensate for weakness in lower limbs and can safeguard him or her against falling. The goals of such devices are to assist the therapist so that they may safely train patients in standing, walking, and performing balance activities early after injuries.…”