Design of a Robotic Equine Forelimb for Testing Load-Bearing Rehabilitative Devices

Abstract

Because horses are animals of flight, bone fractures in the horses' limbs are quite common. When foals fracture a bone in their leg, the healthy leg is often compromised. During convalescence, the animal tends to overstress the healthy leg in an attempt to relieve the stress on the injured leg. This results in angular limb deformities, lax tendons, laminitis, and similar problems. These problems could possibly be avoided through a load-bearing device that would relieve the additional weight from the foal's limbs.

In order to allow for in-vitro testing of such a load-bearing device, this thesis describes the design, analysis, and procedure of construction of a robotic replica of a foal's limb. In particular, the robotic replica has been designed to replicate all of the anticipated motion of a foal's limb, including walking, shifting weight from one leg to the other, and kicking, for example, using gait-analysis data from an actual horse's gait. From such data, the robotic replica has been designed in IDEAS and analyzed using multibody dynamics simulations code and the finite-element-analysis software ANSYS. To evaluate the function of the robotic replica, a control system was developed to reproduce observed gait characteristics. Comparison of the computer-simulated gait with the observed gait showed that a linear feedback control algorithm resulted in a response adequate for the proposed function.

The proposed robotic replica has the potential for aiding in the development of several other bioassistive devices. With minor modifications, the robotic replica could be used to test a device design to transfer load from the cannon bone to the ground for an animal inflicted with laminitis (founder). These possibilities should be investigated in the future.