Abstract Ultrasonic sensors detect objects by transmitting a pulse and receiving an echo. The piezoelectric type of ultrasonic sensor is a stable but poorly-damped resonant system, which helps when initiating a pulse but hurts when terminating a pulse. To enhance range and resolution, short pulses are preferred over long pulses, which motivates the application of time-optimal control principles. This presentation first discusses how implementation constraints influence the formulation of the control problem, and then presents a model-free and robust solution to this control problem; comparison with standard design methods reveals the benefits of the proposed solution.