Accurate Control of Sound Field Amplitude for Ultrasound Haptic Rendering Using the Levenberg-Marquardt Method

Accurate control of the sound field amplitude is essential for providing various tactile experiences using ultrasonic phased arrays. In this study, we evaluate a method for optimizing the transducer phase by solving the least squares problem for the sound field amplitude using the Levenberg-Marquardt method. We demonstrate that the proposed method can reproduce the amplitude distribution with higher accuracy than the conventional algorithm, and the computation time is shorter when there are many points where the pressure is to be suppressed. This property makes this method suitable for controlling the sound field when the scattering effect is large. In the simulation of tactile sensation presentation inside a lightly grasped hand, it is shown that our method can properly present tactile sensation using scattered sound waves, even when there is an occlusion problem, and achieves better performance than other methods.