  Utilizing orthoses and exoskeleton technology in various applications and
medical industries, particularly to help elderly and ordinary people in their
daily activities is a new growing field for research institutes. In this paper,
after introducing an assistive lower limb exoskeleton (RoboWalk), the dynamics
models of both multi-body kinematic tree structure human and robot is derived
separately, using Newton's method. The obtained models are then verified by
comparing the results with those of the Recursive Newton-Euler Algorithms
(RNEA). These models are then augmented to investigate the RoboWalk joint
torques, and those of the human body, and also the floor reaction force of the
complete system. Since RoboWalk is an under-actuated robot, despite the
assistive force, an undesirable disturbing force exerts to the human. So,
optimization strategies are proposed to find an optimal design to maximize the
assistive behavior of RoboWalk and reduce joint torques of the human body as a
result. To this end, a human-in-the-loop optimization algorithm will be used.
The solution of this optimization problem is carried out by Particle Swarm
Optimization (PSO) method. The designed analysis and the optimization results
demonstrate the effectiveness of the proposed approaches, leading to the
elimination of disturbing forces, lower torque demand for RoboWalk motors and
lower weights.
