Towards the Development of an Adaptive Rehabilitative Device

Abstract

Balance impairments severely affect the health and well-being of patients across multiple population groups. The most common treatment compensates for impaired balance by prescribing canes, which increase support base area, reduce paretic-limb load, and provide somatosensory feedback. However, to improve the quality of life of patients, there is a need to develop a walk-aid that can actively improve the user’s balance. In upper-limb rehabilitation, robot-aided therapy has shown to accelerate the recovery of the hemiparetic arm in stroke patients. The device’s embedded performance-based impedance control algorithm adjusts the support it provides a patient according to their ability, weaning them off dependence.

Deploying the promising potential of robot-aided therapy to address the challenge of improving balance ability in impaired subjects, this study proposes the development of a variable impedance cane that progressively reduces the level of assistance it provides as user performance improves to encourage unaided balance. To achieve the design of this device, this study explored an experimental procedure and a mathematical model that advances our understanding of human balance. Potential adaptive mechanisms and a control feedback loop structure for the device were also proposed.

An instrumented cane that measured load, grip pressure, and cane motion was developed and shown to be capable of measuring user balance performance in a pilot human subject study. The mathematical model successfully quantified neural strategies that humans may be employing under various balance conditions and distinguished its effects from biomechanics. Finally, prototypes of several adaptive impedance mechanisms along with their design specifications were proposed. These results serve as a foundation for the future development of an intelligent, adaptive walk-aid that will improve unaided balance in impaired subjects.