Bio-Kinematic Design of Individualized Lift-Assist Devices

Rising from a chair is a fundamental movement in daily life and a prerequisite for independent functional ability. Yet, it remains one of the most biomechanically demanding activities as it requires high levels of neuromuscular coordination, muscle strength and postural control (Ellis et al. J Biomed Eng 6:113–120 (1984), [3]). While standing up is considered a natural ubiquitous skill it becomes increasingly difficult with age. To prolong the independence of elderly we present a novel computational design procedure for lift-assist devices that are individualized to the user while complying with the limited space within the chair. Given marker-based sit-to-stand motion data task positions are defined to carry out a finite position synthesis of a four-bar linkage that provides user-specific guidance of a seat. The four-bar linkage combined with the lower limb of a user generates a biologically inspired six-bar linkage. Thus, accomplishing a bio-kinematic design of linkages where this contribution provides an exemplary design session.