In this presentation, Dr. Naser Mehrabi from the University of Waterloo demonstrated how MapleSim was used to create a musculoskeletal model of lower-extremities to stimulate forward dynamics of cycling. This research, originally presented at the 2016 International Conference on Multibody System Dynamics, involves the development of a musculoskeletal model of lower-extremities and a neuromuscular controller to simulate forward dynamics of cycling.
The musculoskeletal model consists of HAT (head-arm-trunk), thigh, shank, and foot connected to the pedal and crank via revolute joints. The HAT is assumed to be fixed with respect to the seat, and the foot is rigidly attached to the pedal. The ankle was assumed to be fixed and not produce any power. This assumption resulted in a one degree-of-freedom model with five actuating muscles per leg. An obstacle-set method was used to compute muscle length and moment arms, and a modified Hill-type muscle model was used to simulate muscle contraction dynamics. A novel (muscle) synergy based controller was developed to simulate the cyclist neuromuscular system during sub-maximal cycling, and a neuromuscular fatigue model was incorporated in the model to study the individual skeletal muscle activities during fatiguing exercises.