Cost-equivalencing discretization of a class of bang-bang guidance laws

Bang-bang guidance laws are encountered in several situations like in the saddle-point solution of some continuous-time pursuit-evasion games, and in the solution of time-optimal control problems. For the purpose of digital implementation, these continuous-time bang-bang control laws must be converted into digital control laws. The paper presents a novel technique for optimal digital implementation of a class of bang-bang control laws in linear systems. This technique delivers a discretization of the continuous-time laws and is shown: 1) to achieve the same cost as the optimal sample and hold (SH) approximation of the continuous-time laws, and 2) to be implementable (the optimal SH approximation is not). The cost-equivalencing technique is applied to the digital implementation of the continuous-time DGL/0, DGL/1, and DGL/C game theoretic guidance laws.