A three-dimensional dynamic posture prediction model for in-vehicle seated reaching movements: development and validation

A three-dimensional dynamic posture prediction model for simulating in-vehicle reaching movements is presented. The model employs a four-segment 7-degrees-of-freedom linkage structure to represent the torso, clavicle and right extremity. It relies on an optimization-based differential inverse kinematics to estimate a set of four weighting parameters that quantify a timeconstant, inter-segment motion apportionment strategy. In the development 100 seated reaching movements performed by 10 subjects towards five in-vehicle targets were modelled, resulting in 100 sets of weighting Statistical analysis was then conducted to relate these parameters to and individual attributes. In the validation phase, the generalized model, parameter values statistically synthesized, was applied to novel data sets 700 different reaching movements (towards different targets and/or by subjects). The results demonstrated the model's ability to generate close in prediction: the overall mean time-averaged error in joint angle 5.2°, and the median was 4.7°, excluding reaches towards two extreme targets which modelling errors were excessive). The model's general success in and its unique characteristics led to implications with regard to the and underlying control strategies of human reaching movements.