Design of a Two Arms Exoskeleton as Haptic Device for Virtual Reality Applications

The work investigates a solution of powered upper arms exoskeleton designed as haptic device for use in VR scenarios. The mechanical structure and the actuation system of the exoskeleton system are presented. To develop a powered upper limbs exoskeleton possessing, natural safety and transparency in the mutual “man-robot” interaction, the hybrid actuation approach is used. The latter includes in each joint parallel actuation of pair pneumatic actuators and a back drivable direct current (DC)-motor. An impedance controller with model feedforward compensations and an algorithm for joint torque control are designed, in order to provide accurate force response from the virtual environment to the operator. For this purpose, computer simulations are carried out to assess the developed exoskeleton capabilities to provide forceful effect on the operator, in the full range of arm joint motions. The experiments demonstrate that by proper selection of the additional DC actuation the desired power feedback can be achieved throughout the exoskeleton’s workspace.