H/sub /spl infin// tracking control of a rigid spacecraft

The attitude tracking control problem of a rigid spacecraft with external disturbances is addressed using the concept of extended disturbance and the inverse optimal control method. The proposed attitude tracking control law is inverse optimal with respect to a meaningful cost functional and the associated Lyapunov function satisfies a Hamilton-Jacobi-Isaacs partial differential equation. Hence, it is H/sub /spl infin// optimal with respect to the extended disturbance. The performance limitation of the H/sub /spl infin// inverse optimal PD control law is also analyzed.