Haptic servos: self-contained vibrotactile rendering system for creating or augmenting material experiences

When vibrations are synchronized with our actions, we experience them as material properties. This has been used to create virtual experiences like friction, counter-force, compliance, or torsion. Implementing such experiences is non-trivial, requiring high temporal resolution in sensing, high fidelity tactile output, and low latency. To make this style of haptic feedback more accessible to non-domain experts, we present Haptic Servos: self-contained haptic rendering devices which encapsulate all timing-critical elements. We characterize Haptic Servos' real-time performance, showing the system latency is <5 ms. We explore the subjective experiences they can evoke, highlighting that qualitatively distinct experiences can be created based on input mapping, even if stimulation parameters and algorithm remain unchanged. A workshop demonstrated that users new to Haptic Servos require approximately ten minutes to set up a basic haptic rendering system. Haptic Servos are open source, we invite others to copy and modify our design.