Welcome
Durable Tactile Sensing for Robotic Fingers
Optical tactile sensors designed for durability, maintainability, and practical use in robotic systems.
Optical Tactile Sensing
Our Research
Tactile Sensors for Robotic Hands
Research of compact optical tactile sensors for humanoid robotic fingers, with emphasis on durability, tactile image quality, graceful failure, and simple field replacement.
Simple Connection and Live Tactile Imaging
A standard USB connection provides live tactile imaging on a computer. This demonstration shows the sensor connected to a Mac and displaying the tactile camera output in real time.
Large Robotic Finger — Tactile Imaging Demonstration
This demonstration shows real-time tactile imaging with the larger robotic finger. Surface features and contact patterns are captured optically as objects are pressed against and moved across the compliant sensing surface.
Smaller Robot Finger - Tactile Imaging
similar tactile imaging capability has been incorporated into a substantially smaller, humanoid-scale finger
Rapid Sensor Replacement and LED Illumination
The tactile sensor cartridge is designed for rapid removal and replacement without tools, wiring changes, or disassembly of the robotic finger. The demonstration also shows the internal LED illumination used for optical tactile imaging.
Tactile Imaging with Multiple Sensors
Tactile images obtained from several independently fabricated sensors demonstrate the imaging capability of the optical tactile finger design across multiple sensor cartridges.
Accelerated Surface-Abrasion Test
Abrasion Test in Operation
Resistance to abrasive surface damage was evaluated using a rotating-drum sanding apparatus. The sensor is held against abrasive paper mounted on a controlled-speed drum while the applied load and elapsed time are recorded. The apparatus provides an accelerated comparative measure of protective-film durability.
Abrasion Test Conditions
Test Conditions
- Drum diameter: 3 inches
- Drum length: 4½ inches
- Drum speed: 80 rpm
- Abrasive paper: nominally 400 grit
- Digital-scale reading: nominally 200 g
- Abrasion direction: along the sensor’s long axis, from back to front
- Endpoint: first visually detectable rupture of the protective film
Apparatus Components
The representative components used to construct the apparatus are listed below. Equivalent components may be substituted where appropriate.
Purchased Components
• Bringsmart 24 V, 80 rpm DC worm-gear motor
• POWERTEC three-inch oscillating-sander rubber drum
• Digital scale
• Dark Stone sanding sleeves
• Lam(MS)pen 24 V, 10 A switching power supply
• Qinhan sanding-drum mandrel
• Bokwin 8 mm-to-10 mm shaft coupling
• ZK-BMG DC motor speed controller
• 2020 aluminum T-slot framing, corner brackets, end caps and rubber feet
• Vovioir digital kitchen timer
Fabricated Components
• Sensor-mounting fixture
• Load-application arm bracket
• Speed-controller mounting bracket
Repetitive Probe Durability Test
RPT Test in Operation
The video shows the probe repeatedly applying a controlled 39.2 N (4.0 kgf) load to the sensing surface.
Resistance to repeated concentrated loading was evaluated using a repetitive probe test (RPT). A motor-driven probe repeatedly contacts the tactile surface under controlled force and timing. Changes in surface appearance, tactile imaging, and interfacial adhesion are monitored throughout the test.
Test Conditions
- Probe diameter: 6 mm
- Probe-face angle: 20°
- Probe edges: Rounded
- Peak applied force: 39.2 N (4.0 kgf)
- Cycle rate: 45 contacts per minute
- Contact timing: 0.3 seconds at force followed by 0.5 seconds released
- Inspection frequency: As necessary during the first day and daily thereafter
The sensors are inspected for probe imprinting, ring formation, TPU blistering, delamination at the silicone–TPU or silicone–cartridge interfaces, TPU rupture, and silicone-gel rupture.
Parts List
Purchased components
- FUYU FSK40J linear guide with stepper motor
- BANRIA 42/57 stepper-motor drive controller
- DYMH-103 10 kg load cell
- QILICHUANGAN load-cell indicator
- JOYLIT 24 VDC, 5 A, 120 W power supply
- 2020 aluminum T-slot framing
- Corner brackets, end caps, and rubber feet
Fabricated components
- 6 mm probe tip with a 20° contact face
- Probe-tip-to-load-cell shaft
- Sensor and finger mounting fixture
- Load-cell output mounting bracket
- Stepper-motor controller mounting bracket
- Load-cell-to-linear-drive bracket
Technical Publication
The design, fabrication, tactile performance, and durability testing of these sensors are described in our recently published technical paper. Accelerated abrasion and repetitive loading tests demonstrate substantially improved durability, gradual rather than catastrophic degradation, and rapid sensor replacement for maintainable robotic tactile sensing.
A Durable Vision-Based Tactile Fingertip for Robotic Manipulation
Optical Tactile Sensor Research
F. Richard Cottrell (Founder & Owner)
About Richard
Education:
1965-1968 Sc.D. Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
1962-1965 B.S.Ch.E., Chemical Engineering, University of Massachusetts, Amherst, Massachusetts
Contact Us
Cottrell Technology
This website uses cookies.
We use cookies to analyze website traffic and optimize your website experience. By accepting our use of cookies, your data will be aggregated with all other user data.