Harness racing is one of the oldest traditions in horse racing in the world. The chariot seems to have significantly influenced the modern racing sulky (some sulky are at Jerald Sulky or other sites like http://www.sulkyshop.co.nz/ - image at left source). With the reinvigorated harness industry in Maine it is time for us as engineers to look and see if we have a role in this great sport. And, like any sport, it is fun because the margins are so small that every factor matters.
The gait of a trotter, just based on a visual cues and the experience of riding in a cart behind a horse, involves some fore and aft motion of the center of mass of the horse even when traveling at a steady speed. In other words, the center of mass of the horse accelerates forward, and then slows (if not revering momentarily) and then returning to a forward motion. This reversal is reasonable and is probably a necessary part of the gait of a quadruped. The efficiency associated with reducing the fore and aft motion is clearly established in racing:
http://www.rvc.ac.uk/SML/Research/Stories/ModernRidingStyle.cfm
It is clear that the driver and sulky would be more efficient if they could move forward at a constant velocity. A system is thus desirable that would store the extra energy during the forward surge of the horse and release it during the slack period of the horse motion. A spring is able to do this since it stores energy and releases it, with a small amount of damping used to eliminate oscillations. However, the spring would have to be tuned to each rider, to a horse and perhaps even to the speed at which the horse was moving. Alternatively, a smart actuator could be used which would modify the stiffness to obtain a smooth forward motion of the sulky.
This project will develop a system to replace the arms of the sulky with electro-mechanical actuators which will minimize the acceleration of the sulky. The group will be responsible for concept design, development of models of the motion, integration of available experimental data and design and build of a prototype. Testing will be done in cooperation with Animal and Veterinary Sciences, although this will only be done after the prototype has been shown to meet performance and safety criteria. The group will also be responsible for review of the appropriate rules (http://www.ustrotting.com/).
The outside support on this project will be extensive with help being available from Dr. Robert Causey D.V.M, Ph.D. (UMaine Faculty Member), Dr. Jeff Thomason (Ontario Veterinary College) and Dr. Raoul Reiser (Colorado State University)