A disturbance/uncertainty estimator based integral sliding-mode control approach is introduced. Explicit mathematical expressions for robust stability, performance, and bandwidth requirement are derived. The integral sliding-mode controller is built to satisfy certain industrial criteria. It is integrated into the robustness analysis via its quasi-linear representation. The proposed methodology is experimentally verified on a high-precision gimbal control application. It is seen that the estimator works well and significantly improves performance and robustness in the presence of disturbances and uncertainties.