HACHIStack

We present a novel photo touch sensing architecture, HACHIStack. It can measure the approaching velocity of an object and predict its contact time with the touch screen using two optical sensing layers above the surface. The photo sensing layers form three unique capabilities: high-speed sampling, velocity acquisition, and contact time prediction. This work quantitatively examines these capabilities through two laboratory experiments, and confirms that the capabilities of HACHIStack are sufficient for multimodal interaction, in particular, touch-based interaction with haptic enhancement. We then present three applications with HACHIStack: 1) chromatic percussions (xylophone and glockenspiel) with haptic feedback; 2) no-delay haptic feedback with the sensation of tapping on various simulated materials (e.g., rubber, wood and aluminum); and 3) a virtual piano instrument that allows players to perform weak and strong strokes by changing the tapping velocity.