In this paper, we propose static-balancing mechanisms to permit perfect and approximate compensation of gravitational loads for an articulated-cable leg-orthoses. Such gravity-compensation of loads (arising from both user's leg as well as attached orthosis) can significantly improve the transparency and performance of the rehabilitation exoskeletons for gait training. The direct application of traditional static balancing methodologies (e.g. adding balancing weights or even auxiliary linkages) places a very restrictive set of conditions for mass, inertial and geometric parameters to achieve balancing for all leg postures in the configuration space. Greater design freedom and flexibility to achieve balancing conditions can be obtained by coupling semi-active elastic elements (such as coil and torsion springs) together with linkages. The effectiveness of this approach is demonstrated on a scaled physical leg-orthosis emulator in terms of significant reduction of actuation to realize the gravity-compensation.
|Number of pages||20|
|Journal||Mechanism and Machine Theory|
|Publication status||Published - Jan 2019|