The handheld device uses an onboard camera to save a picture of each object for documentation. It also uses a Sharp digital IR proximity sensor and timer to estimate the average velocity over the last 6.5 cm before contact. The onboard Raspberry Pi 2 and the 8 channel 12-bit ADC record data to a USB flash drive from the force sensor, contact microphone, and accelerometer at 500 Hz and from the heat-transfer sensor and temperature sensor at 100 Hz. More details here.
We used this 1 degree-of-freedom (1-DoF) robot to touch various tactile sensors to material samples. This robot’s simple, linear motion is useful for testing sensors in a repeatable and controlled fashion.
1-DoF Device w/ Mass-Spring-Damper
This device uses a PA-15-6-11 High Speed Linear Actuator and mass-spring-damper system to touch a tactile sensor to a test objects with compliance varying speed. The actuator is controlled through equilibrium point control which assigns an equilibrium point and virtual spring and damper to pull the robot’s linkage towards a desired location. To mechanically decouple the force sensor from the actuator, the sensor is mounted to a mass of 1.45 kg and connected via physical springs and dampers to the actuator.