Adaptive observed-based backstepping control for quantized robot arms

Most existing control studies of robot arms are restricted to nonlinear systems but overlook real-time signal transmission. To resolve this issue, a novel observer-based backstepping control scheme, where both the input and output signals are quantized before transmission. Since quantized outputs cause discontinuities in the virtual controllers, auxiliary intermediate controllers are first designed using unquantized signals. By substituting quantized states into these controllers, the actual torque controller is obtained. Lemma 5 is introduced to handle quantization errors. And a novel quantized state observer with n-dimensional states is devised to evaluate the unmeasurable states. The validity of the presented scheme is verified via an example.