Control of the lower leg during walking: a versatile model of the foot.

An improved biomechanical model has been implemented for use in gait simulations and functional electrical stimulation (FES). The novelty includes longitudinal bending of the foot which implements geometrical changes that appear "healthy-like" during the stance phase of gait. The simulation uses optimal control which minimizes the activation of flexor and extensor muscles, as well as the tracking error. Correspondingly, the results of the bending foot model, contrasted against a rigid foot biomechanical model, show that torques in the knee during foot contact were as much as 36.9 Nm (46.1%) lower, while muscle excitation was on average 6.1% lower. The simulation also shows that the shank angle of the bending foot model was virtually identical to that of the rigid foot model. However, this model's worth is most prevalent in its use for stance phase control in individuals who use multichannel FES. Notably, it can also be used for simulating the gait of individuals who lack ankle articulation and use an active transfemoral prosthesis.