Functional design for customizing sit-to-stand assisting devices

Standing up refers to the transition from the seating to the standing postures to perform a movement that involves several body segments and requires both voluntary action and equilibrium control during an important displacement of the body Centre of Gravity (COG). This task can be considered very important for people with reduced mobility to achieve minimal independence in Activity of Daily Living (ADL). In this paper, we propose solutions for the homecare of persons with reduced mobility, describing a functional design to customize assisting devices for the Sit-to-Stand (STS). In particular, the support mechanism that generates the requested motion and sustains the body of a person can be synthesized ad-hoc according to the experimental data of the subject. Experimental tests carried out during the Sit-To-Stand are used to track and record point trajectories and the orientation of the trunk of an individual, and they are used to design a 1-DOF mechanism able to reproduce the assigned rigid-body motion. A four-bar linkage has been synthesized according to the desired features. Simulation results are reported to illustrate the engineering soundness of the proposed mechatronic solution.