A non-identification adaptive backstepping approach to global output feedback tracking control of nonlinear systems with input quantization

A new output feedback control approach is proposed to address the global practical tracking issue for a class of nonlinear input-quantization systems with polynomial growth condition, which introduces a non-identification adaptive gain in the backstepping design instead of constant control gain. This approach is applicable to any quantizer with sector-bounded characteristic (e.g., logarithmic quantizer, hysteresis quantizer). Except for using the quantized signal in the observer, the controller design in this article is completely independent of the input quantizer due to the introduction of adaptive gain. Different from the existing results, a suitable quantizer can be selected as needed and it is unnecessary to redesign the observer and controller. By combining the dynamic-gain scaling technique with the backstepping method, the design problem of control gains is transformed into choose the dynamic gain indexes, which significantly reduces the computational complexity of designing controller.