Multidirectional transparent support for overground gait training

Abstract

Abstract-Gait and balance training is an essential ingredient for locomotor rehabilitation of patients with neurological impairments. Robotic overhead support systems may help these patients train, for example by relieving them of part of their body weight. However, there are only very few systems that provide support during overground gait, and these suffer from limited degrees of freedom and/or undesired interaction forces due to uncompensated robot dynamics, namely inertia. Here, we suggest a novel mechanical concept that is based on cable robot technology and that allows three-dimensional gait training while reducing apparent robot dynamics to a minimum. The solution does not suffer from the conventional drawback of cable robots, which is a limited workspace. Instead, displaceable deflection units follow the human subject above a large walking area. These deflection units are not actuated, instead they are implicitly displaced by means of the forces in the cables they deflect. This leads to an underactuated design, because the deflection units cannot be moved arbitrarily. However, the design still allows accurate control of a three-dimensional force vector acting on a human subject during gait. We describe the mechanical concept, the control concept, and we show first experimental results obtained with the device, including the force control performance during robot-supported overground gait of five human subjects without motor impairments.

A body weight support system extension to control lateral forces: Realization and validation

“…An example of a commercially available body weight support system is the Lokolift [7]. The scope of body weight supported gait training has recently been expanded to large workspace overground walking with the development of the ZeroG (Bioness, Inc., Valencia, CA, U.S.), which follows the subject in the walking direction by means of a trolley that runs on a rail and contains a pulley mechanism with a series elastic actuator to unload the subject [8], and with the development of the FLOAT (Lutz Medical Engineering, Switzerland), which allows transparent 3D support during overground gait, by means of four actuators and moving deflection units on two rails [9].…”

Body weight support impacts lateral stability during treadmill walking

“…First, BWS systems that use cable-driven actuation routed through an overhead suspension could provide lateral restoring forces (Vallery et al, 2013) that decrease the requirements to actively control lateral stability . If the suspension restricts lateral translations, the BWS system will act as a pendulum and pull the user beneath the fulcrum (Pennycott et al, 2011).…”

Observing the State of Balance with a Single Upper-Body Sensor

“…A limitation of IMUs is that they do not allow to directly measure one highly specific predictor for imminent falls: linear velocity in vertical direction. This has proven to be a valuable source of information both in literature (Wu, 2000;Bourke et al, 2008) and in our own experience with the FLOAT rehabilitation robot of Vallery et al (2013). Despite recent advances in filtering techniques for IMUs (Seel et al, 2014), they cannot deliver linear velocity information without drift or additional assumptions.…”