MSC Software Corporation

The medical industry is moving in a direction towards robotics to help patients in the rehabilitation process. Gait training (over ground or on a treadmill) has become an essential part of rehabilitation therapy in patients suffering from gait impairment caused by disorders such as stroke, spinal cord injury, and multiple sclerosis. A focus on the human in collaboration with a robot puts emphasis on the adaptability, safety, and task specificity of robotic assistance. Hence, in the development of novel rehabilitation prototypes engineers face the challenge of combining suitable design concepts, high performance actuator technologies, and dedicated control strategies in view of improved physical human-robot interaction (HRI). The improvements should lead to a better insight into effectiveness of robot-assisted rehabilitation and ultimately, lead to therapies that are more effective. One of the approaches to facilitate the design process, in terms of development time, functional and safety evaluation, is using computational multibody simulations. Nowadays, multibody modeling and simulations are recognizable as an efficient and relative inexpensive evaluation approach. Due to the continuously increasing complexity of the wearable robots, almost any study conducted in the field of robotics can profit from a simulation of the system behavior, foregoing experiments on a real platform. Moreover, an advantage of using multibody modeling represented by the possibility to predict various outputs that are difficult, dangerous, or even impossible to reproduce in the real experimental setup.

The 3D model of a novel CORBYS rehabilitation device has been developed and co-simulated with the human body using object-oriented multibody dynamics software, Adams.

Adams gave researchers the additional insight they needed on the push-pull actuation system. The simulation results show that the transmission efficiency of the PPC is dependent on nonlinear friction between the tendon and the sheath. While the friction was influenced by an attached load to the cable and the curvature of the PPC. The simulation results had an impact in defining the actuation system parameters and appropriate control implementation design. These insights helped them present a working concept, which will open doors for further exploration for research and development.

According to modeling experience in Adams, the team confirm that multibody simulation tools are very effective in cases when the main design, technical, and functional characteristics of the real system are accurately reproduced in computational model. In order to obtain a useful functional model, users need a good understanding of the governing mechanics describing a physical system to make relevant choices between numerous simulation platforms.

• Studied human-robot interaction forces during walking exercise
• Simulation helped make sure the working prototype met the safety requirements for patients
• Evaluated the push-pull cable actuation system followed by control strategies optimization