Currently, more and more tasks require robots to complete, and sensory input similar to that of humans is essential. Tentacles are tactile sensory hairs that exist on certain mammals, supplementing the function of the skin at night or in narrow environments, for external environmental perception. Inspired by the structure of animal antennae, researchers have begun to explore the research of whisker sensors.

Problem solved and its significance

Tactile sensors can compensate for the shortcomings of visual sensors, and are not affected by ambient light and unstructured environments. By directly contacting objects, they can perceive tactile information on the surface of the object, quickly obtain information such as contact position, contact force, object shape, texture, temperature, etc., which is of great significance for robots to improve human-computer interaction and achieve precise operation.

Methods and Innovation Points

1. Design of whisker sensor unit and output voltage model

Inspired by the animal whisker sensing mechanism and combined with the excellent perception ability of iron gallium alloy wire for tactile information in the height direction, the bias magnetic field size, length, tilt angle, etc. of the sensor unit were determined. The sensor unit was integrated into a 4 × 2 array and an output voltage model of the sensor unit was established.

2. Performance testing of whisker sensor array

A static performance testing system was established, and the measurement range of the texture height of the unit was determined to be 0.01-1.6mm, with a sensitivity of 243.3mV/mm.

Built a dynamic performance testing system. Tested the response of the sensor unit under different frequency dynamic forces. The repeatability, response, and recovery time were characterized using a 6Hz square wave force of 26ms and 25ms, respectively. The voltage waveform has consistency in 50 cycles of testing.

3. Texture recognition and reconstruction

When the sensor unit slides over the sample at a speed of 6.5mm/s, the output voltage waveform shows a shape corresponding to the texture of the sample, and the surface texture of the sample can be recognized through the output voltage waveform.

We tested the use of an "I" - shaped sample, with a robotic arm loaded with an array sliding parallel across the surface of the sample. The output voltage and reconstruction results are shown in the figure, and texture 3D reconstruction can be performed using a sensor array.

Inspired by the animal whisker sensing mechanism, whisker sensor units and arrays for texture recognition and reconstruction were designed and fabricated, and a sensor unit output voltage model was established. The sensor unit and array were separately loaded onto a robotic arm for sample surface sliding experiments, and the collected output voltage was used to identify and reconstruct the surface texture of the sample. The designed whisker sensor unit and array are of great significance in guiding the adjustment of operating strategies for robotic arms and improving human-machine interaction processes.

Source: Sensor Expert Network