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 biomechan-ically 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.