Nonlinear Speed Control for Automotive Engines

Previous research has shown that high performance engine controllers could be used in conjunction with electronic controls on automatic transmissions to improve shift quality. Due to the highly nonlinear nature of automotive engines and the need for robustness of the design, sliding control is a likely choice. However, a standard sliding derivation for an automotive engine results in an unpractical control law. An alternate method of deriving sliding controls can be used that defines one of the states to be a synthetic control. A control law is derived assuming the synthetic control as the input. A second law must then be derived to control the synthetic state. For automotive engines, the two surface controller is be much simpler and more robust than the standard control law. By taking advantage of the fact that the engine only has one output, it is possible to develop a method of coordinating the spark and throttle inputs in such a way as to take advantage of their respective strengths. Experimental implementation of the two surface control law with combined spark/throttle control has verified the performance and robustness of this algorithm.