The active wave control of the linear, axially moving string with general boundary conditions is presented in this paper. Considerations of general boundary conditions are important from both practical and experimental viewpoints. The active control law is established by employing the idea of wave cancellation. An exact, closed-form expression for the transverse response of the controlled system, consisting of the #exible structure, the wave controller, and the sensing and actuating devices, is derived in the frequency domain. Two actuation forces, one upstream and one downstream of an excitation force, are applied. The proposed control law shows that all modes of the string are controlled and the vibration in the regions upstream and downstream of the control forces can be cancelled. However, these results are based on ideal conditions and the assumption of zero initial conditions at the non-"xed boundaries. E!ects of non-zero boundary motions at the instant of application of the control forces are examined and the control is shown to be e!ective under these conditions. The stability and robustness of the control forces are improved by the introduction of a stabilization coe$cient in the control law. The e!ectiveness, robustness and stability of the control forces are demonstrated by simulations and veri"ed by experiments on axially moving belt drive and chain drive systems.
2000 Academic Press