FlickerTac: Flickering LED Driven Photometric Stereo for Event Vision-Based Tactile Sensors

Abstract

Tactile sensing at high speed and resolution is critical for robotic perception and control. Existing vision-based tactile sensors (VBTSs) achieve high spatial accuracy but suffer from degraded performance in dynamic interactions due to motion blur and low frame rates, limiting their effectiveness in fast manipulation. Event-based cameras, with their high-temporal-resolution output, offer a promising alternative—but their inability to capture static scenes and absolute intensities has hindered their use for dense 3D reconstruction even under static contact conditions. We introduce FlickerTac, the first Event Vision-Based Tactile Sensor (EVBTS) capable of performing photometric stereo-based dense 3D reconstruction. FlickerTac replaces conventional 3-channel RGB illumination with time-multiplexed, phase-shifted flickering LEDs to encode directional shading into temporally separated channels. A lightweight neural network then maps these spatio-temporal representations directly to surface gradients, which are integrated to recover dense depth maps. Our design enables high-speed, accurate tactile 3D geometry estimation. Extensive experiments demonstrate that FlickerTac achieves millimeter-scale depth accuracy competitive with state-of-the-art VBTSs, while operating at 125 Hz—unmatched by existing frame-based VBTSs.