In response to the precision motion industry's growing demand for higher accuracy, faster, and robustness, the design of conventional linear time-invariant (LTI) controllers has reached its inherent limits, which is the waterbed effect and Bode's gain-phase relationship. To overcome these limitations, a Constant in gain, Lead in phase (CgLp) element has been introduced. This element combines a reset low pass filter with a linear lead element, providing additional phase without affecting the constant gain through the phase characteristics of the reset element.

Previous researches have explored the sequence of first-order reset element(FORE) and Lead element within the CgLp(i.e. FORE-Lead and Lead-FORE CgLp), revealing a trade-off between transient overshoot and steady-state noise suppression. This thesis proposes a tunable CgLp architecture that is capable of achieving performance between FORE-Lead and Lead-FORE CgLp. The tunable CgLp provides compromise transient overshoot and steady-state noise attenuation, offering the possibility of optimizing transient response under a satisfying noise performance.

However, tunable CgLp cannot reduce higher-order harmonics and associated errors. Thus, the second part of this thesis introduces a framework that employs filters to shape nonlinearity. The feasibility of using notch and anti-notch filters to enhance disturbance rejection performance is theoretically analyzed and validated using a mass plant. Design recommendations for this framework are also provided. Nevertheless, tunable CgLp and the nonlinearity shaping architecture can be used in combination, which provides the potential to further enhance the performance of reset control systems.