Development of a human body upper arm dynamic model for compensation and control of a body mounted robot

Abstract

Supernumerary Robotic Limbs (SRLs) are robotic manipulators worn on the human body which seek to augment the abilities of their wearers. A critical element to the design and implementation of these robotic systems is the development of a control framework which allows for intuitive control. The control of SRLs is further complicated by the relative motion of the manipulator with respect to its environment due to motion of the human body. Developing a dynamic model of the human body on which an SRL is mounted can serve as a useful tool, both for understanding the configuration of the SRL with respect to its user and for controlling the mechanism given a well-structured task process model. Subspace identification was investigated as a possible technique for generating a dynamic model of the human body from a set of defined input and output data. To validate the potential applicability of this approach, a simulated system was developed to model simple human arm reaching motions. From this simulated system, a set of virtual measurements were made to construct input/ output data sets. Subspace identification applied to these data sets indicated the applicability of the approach. Further testing was then conducted via the development of an experimental system for measuring actual human reaching motions. Using appropriate measurements, the simulation framework was reproduced with a physical system. Applying subspace identification techniques to the real data, a dynamic model was produced which could effectively reproduce the arm configuration. The success of both the simulated and experimental systems indicates that subspace techniques may be appropriate for generating human body dynamic models.