<p>The constrained super-twisting sliding-mode control approach is applied in this article to achieve beam and ball system stability. First, this system’s dynamic equations have been extracted. Because the designed equations contain special terms that cause the state variables to appear in the denominator of the controller, these terms are approximated to avoid singularities in the control signal. The constrained nonlinear controller is designed using a first-order sliding-mode controller for the approximated equations. Additionally, it is employed to generate a smooth control signal and avoid chattering problem, a condition in which the system output variables are never exceeded. The constrained super-twisting sliding-mode controller’s simulation results, along with its application to a laboratory system, show that the system stabilizes and generates a smoothness control signal without going against the state constraints.</p>