# A Hybrid-Frequency Sampling Tactile Sensing System Based on a Flexible Piezoresistive Sensor Array: Design and Dynamic Loading Validation

## TL;DR

A new tactile sensing system using a flexible sensor array and hybrid-frequency sampling achieves high-speed, reliable tactile perception for robotics and wearable devices.

## Contribution

A hybrid-frequency sampling strategy enables high-bandwidth tactile sensing with reduced system complexity and improved reliability under dynamic loading.

## Key findings

- The system achieves an aggregate bandwidth of 36.9 kHz with high repeatability (RSD < 4.9%) and strong linearity.
- Dynamic loading validation shows a strong linear correlation (R² ≈ 0.98) between sensor outputs and actual applied forces.
- The system successfully distinguishes tactile stimuli like tapping, pressing, and stroking with temporal accuracy.

## Abstract

What are the main findings?
It was observed that although Velostat exhibits inevitable temporal drift in absolute resistance, the relative variation in channel responses is sufficiently stable to identify tactile states.System-level validation, supported by RTL simulation, confirmed that the hybrid-frequency scheduler executes deterministic scanning with an aggregate bandwidth of 36.9 kHz. The system exhibits high repeatability (RSD < 4.9%), strong linearity, and robust mechanical durability under cyclic bending.

It was observed that although Velostat exhibits inevitable temporal drift in absolute resistance, the relative variation in channel responses is sufficiently stable to identify tactile states.

System-level validation, supported by RTL simulation, confirmed that the hybrid-frequency scheduler executes deterministic scanning with an aggregate bandwidth of 36.9 kHz. The system exhibits high repeatability (RSD < 4.9%), strong linearity, and robust mechanical durability under cyclic bending.

What are the implications of the main findings?
These results highlight a practical route toward FPGA-based dynamic tactile sensing systems that can capture fast-evolving contact behaviors with zero latency, which are typically missed by conventional e-skins.The work provides experimental evidence that relative-dynamics-based interpretation combined with deterministic hardware timing can mitigate material drift and system latency issues, offering new insight for the design of future soft tactile interfaces.

These results highlight a practical route toward FPGA-based dynamic tactile sensing systems that can capture fast-evolving contact behaviors with zero latency, which are typically missed by conventional e-skins.

The work provides experimental evidence that relative-dynamics-based interpretation combined with deterministic hardware timing can mitigate material drift and system latency issues, offering new insight for the design of future soft tactile interfaces.

A Hybrid-Frequency Sampling Tactile Sensing System Based on a Flexible Piezoresistive Sensor Array is presented for reliable and real-time tactile perception under dynamic loading conditions. While recent studies have developed multi-channel tactile arrays, most systems remain limited by time-dependent drift in channel responses, inconsistent dynamic behavior, or insufficient temporal resolution under simultaneous loading. In this work, a system-level design integrating a flexible piezoresistive sensor array with a real-time data acquisition module is developed, incorporating a hybrid-frequency sampling strategy to reduce system complexity while preserving reliable dynamic response in key sensing channels. Register-Transfer Level (RTL) simulation verified that the hardware scheduler rigorously executed the deterministic scanning logic, demonstrating a strict one-to-one correspondence with the physical hardware signals. The array consists of 34 piezoresistive sensing nodes embedded in an elastomeric substrate. Under the implemented hybrid-frequency sampling scheme, the system achieves an overall effective acquisition bandwidth of approximately 36.9 kHz, while maintaining a repeatability better than 4.9% and robust mechanical durability under cyclic bending deformation. Dynamic loading validation was performed using a self-developed pressure comparison platform for measuring the normal contact force applied on the tactile surface, serving as ground-truth data to verify that the voltages acquired by the proposed system accurately correspond to the actual applied force. Quantitative analysis shows a strong linear correlation (R2 ≈ 0.98) between the e-skin outputs and the reference forces. The recorded responses exhibit clear intensity-dependent trends and good temporal correspondence among sensing nodes, successfully distinguishing tactile stimuli such as gentle tapping, moderate pressing, and firm contact. The system also captures dynamic tactile responses during finger stroking, showing characteristic multi-unit activation patterns under spatiotemporally varying contact conditions. Compared with previously reported tactile systems typically operating below 100 Hz, the proposed design achieves an approximately 10× enhancement in effective sampling capability while significantly reducing system complexity through hybrid-frequency sampling, thereby supporting reliable dynamic tactile sensing in multi-unit arrays. These results demonstrate that the proposed system provides a practical and scalable hardware platform for dynamic tactile sensing in robotics, human–machine interaction, and wearable tactile systems.