Optimization of spring-loaded crutches via boundary value problem.

The objective of the work is to optimize the design of spring-loaded crutches by choosing appropriate spring stiffness based on their dynamic characteristics. It was shown in the literature that ambulation with spring-loaded crutches reduces the initial impulse yielded by ambulation with standard crutches and provides a propulsion mechanism. This research not only provides a genre of the spring-loaded crutches via compliance, but also proposes an approach to optimize the stiffness of the helical spring through studying the dynamics of crutch stance. The method is developed using a boundary value problem and its solution method and is studied numerically. Experiments were carried out on four subjects in a biomechanics laboratory. It suggests that the optimized spring-loaded crutches guarantee the propulsion mechanism at the right time and right position during dynamical ambulation.