Optimal energy management for solar car race

This paper describes a solar car simulation and race strategy program developed for the University of Illinois Sunrayce 95 solar car race team. The goal is to complete the ten-day race course in the minimum total running time, using solar energy alone. In cloudy weather, even the most competitive cars can become energy-limited. The strategic choice in that case, is how fast to drive the car at any point. This can be posed as a global time-minimization problem over the entire race. By breaking up the course into twenty or so segments, the problem can be made tractable enough to solve on a (vintage 1995) portable computer in a few minutes. The parameters varied are the average speeds on each of the segments. A model of the car, information about the course, and weather forecasts all contribute to the calculation of the net drain on the car's storage batteries over each segment. The main constraints are the minimum and maximum battery charge. This article discusses the algorithms used, some of our strategic insights and expectations prior to the race, and how our plans fared in the competition.