Adaptive position following using only position measurement

A drawback of existing adaptive position tracking algorithms is the requirement for velocity measurement or velocity calculation, which in turn requires additional measurement hardware or undesirable numerical differentiation. In this paper, we propose a new adaptive algorithm for single-link robots which requires only position measurement and does not need the measurement or computation of velocities. A novel technique called phase-lead adaptation is used in the algorithm, so that the global stability and tracking convergence are established based on the Lyapunov method. We proposed an adaptive nonlinear controller which contains adaptive inertial and gravity feedforwards and an adaptive phase-lead feedback. Adaptive compensation of friction based on an asymmetric Coulomb model is developed. Hardware implementation has been carried out in the laboratory, and the experimental results are excellent. The same control technique can be applied for general x-y-z type motion systems such as machine tools and positioning tables