Standing balance is a prerequisite to perform a number of daily activities for an active and independent life, from reaching for objects, opening doors, turning on taps, to walking. For healthy persons, standing seems almost effortless, and the control of standing balance appears to be automatic or “involuntary”. The control of standing balance may be compromised or altered in persons with various pathologies (e.g., spinal cord injury, stroke or diabetes mellitus) or may slowly deteriorate during normal aging. Rehabilitation robotics tools have been developed to retrain locomotor, or voluntary movements, yet no methods have focused successfully on rehabilitating the unique functions relating to the control of unperturbed standing balance. Retraining standing balance would have a number of benefits, such as activating neuronal networks that are triggered only when engaged in a balancing task, as well as allowing people to activate their lower limb musculature in a standing posture.
We aim to develop and validate accurate mechanical and physiological models of standing balance that ultimately will allow retraining of the neural control of balance. To achieve this goal, we are developing a novel robotic platform – RISER: Robot for Interactive Sensory Engagement and Rehabilitation – that allows us to investigate the human balance system in a safe, systematic and controlled manner. One of the main advantages of this new robot system is that it allows people (including those with spinal injury or stroke related pathology) to perform standing balance while their body is fully supported, without requiring the normal magnitude of lower limb muscle activation. For this robot, we have designed and prototyped a novel control system that uses the forces applied by subjects on a hexapod robot (Stewart platform) to simulate the control of unperturbed standing balance under a range of conditions. For the current project, we intend to validate mechanical and physiological models of the balance system while investigating the potential to specifically engage the neural networks involved in the control of unperturbed standing balance. We plan to perform pilot experiments to assess and advance the potential of this robotic system as a new rehabilitation tool to retrain balance for persons suffering from a range of pathologies including incomplete spinal cord injury. We will further leverage the research on this advanced platform to identify optimal designs and methods for retraining balance using simpler, single axis systems and new therapy protocols.
Studies have shown that galvanic vestibular stimulation (GVS), which is the application of small currents (1-5 mA) across the vestibular balance system produce an illusion of movement and a reflexive balance response. In collaboration with the School of Human Kinetics, the CARIS lab is examining this phenomenon in greater detail. Specifically, we hope to understand what motion the vestibular stimulation is perceived as, and whether it would be possible to cancel this perception by moving the RISER platform at the same time as the stimulation is applied.
Subjects in the present study stand on the RISER platform and adjust the motion through mouse movements until their perceived motion from the GVS cancels with the platform motion. Further details can be obtained by contacting Eric Pospisil at ericp@interchange.ubc.ca
Balance Simulation
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