Towards a Controlled Orthosis for Sit-To-Stand Support in Independently Living Elderly: Model Development

Sit-to-stand (STS) movements are a daily challenge for independently living elderly. Literature shows a keen interest in using active orthoses to mitigate this problem. However, to design and test advanced control strategies for proof-of-concept orthoses, a validated model of the STS movement is missing. This work presents and elaborates on a model of the kinematics of the lower limb in combination with a human policy which represents the brain-muscle interaction. The model parameters are derived from both healthy and elderly patients. The applicability of the model is investigated by applying two popular control methods for active orthoses: gravity compensation and a control-based method. First, the results show model validation using measured in vivo joint torques from literature and, second, that both methods can be simulated using the developed STS model. This allows for optimizing and testing advanced control strategies in future work.Copyright (c) 2023 The Authors.