Why Touch Matters?
While vision helps a robot find an object, touch helps it manipulate it. Without tactile feedback, a robot blindly crushing an egg or dropping a heavy tool. Tactile sensing closes the loop on physical interaction.
Force Control
Regulating the amount of force applied to polish surfaces, assemble parts, or safely shake a human's hand.
Slip Detection
Sensing micro-vibrations to detect when an object is starting to slip, allowing the grip to tighten instantly.
Strain Gauge Load Cells
Force MeasurementThe standard for measuring weight and force. Uses a resistive foil pattern that changes resistance when stretched or compressed.
How it works
A metal foil pattern is bonded to a structural element. When force deform the structure, the foil stretches, changing its electrical resistance. A Wheatstone bridge circuit converts this tiny change into a readable voltage.
Key Spec
- range:10g - 100+ tons
- accuracy:0.03% - 1%
- axes:1-6 axis (Force/Torque)
Piezoelectric Force Sensors
Dynamic ForceGenerates an electric charge when mechanically stressed. Excellent for detecting impacts, vibration, and dynamic forces.
How it works
Certain crystals (like quartz) produce a voltage when compressed. This effect is reversible (can also create motion). Great for detecting *changes* in force (AC) rather than static weight (DC).
Key Spec
- sensitivity:Very High
- response:Microseconds
- range:Wide dynamic range
Optical Tactile Sensors
High-Res TouchUses a camera looking at the back of a deformable membrane to capture high-resolution 3D texture and force maps.
How it works
A soft elastomer skin is illuminated internally. A camera records the deformation of the skin as it presses against an object. Computer vision algorithms reconstruct surface geometry and contact forces.
Key Spec
- resolution:Camera resolution (Megapixels)
- sensitivity:Micron-level texture
- modality:3D Geometry + Shear Force
Force Sensitive Resistors (FSR)
PressureSimple, thin, flexible pads that decrease resistance when pressed. The "quick and dirty" way to adding touch.
How it works
Conductive polymer ink changes resistance with pressure. Simple voltage divider circuit reads the pressure.
Key Spec
- range:100g - 10kg
- accuracy:Low (±10%)
- thickness:< 0.5mm
Capacitive "E-Skin"
Distributed TouchArrays of soft capacitors that can cover large areas of a robot, giving it "skin" that feels proximity and touch.
How it works
Soft dielectric layer sandwiched between conductive fabric calibration. Deformation changes capacitance. Can often detect objects *before* contact (proximity mode).
Key Spec
- modality:Proximity + Pressure
- coverage:Large area
- flexibility:High
Tactile Technology Matrix
| Technology | Surface Type | Precision | Speed | Cost |
|---|---|---|---|---|
| Load Cell | Hard | Very High | Medium | Medium |
| Piezo | Hard | High (Dynamic) | Very Fast | High |
| Optical (Gel) | Soft | Extreme (Texture) | Slow (FPS) | Very High |
| FSR | Flexible | Low | Fast | Low |
| E-Skin | Soft | Medium | Medium | High |
Sensor Selector
Answer questions to find the perfect tactile sensor.
What are you measuring?
// Reading Force from an FSR
// FSR is connected in a voltage divider configuration with a 10k Resistor
const int fsrPin = A0; // FSR connected to Analog Pin 0
const int ledPin = 11; // PWM LED connected to Pin 11
void setup() {
Serial.begin(9600);
pinMode(ledPin, OUTPUT);
}
void loop() {
int fsrReading = analogRead(fsrPin); // Read analog value (0-1023)
Serial.print("Analog Reading: ");
Serial.print(fsrReading);
// Interpret the pressure
if (fsrReading < 10) {
Serial.println(" - No Pressure");
} else if (fsrReading < 200) {
Serial.println(" - Light Touch");
} else if (fsrReading < 500) {
Serial.println(" - Light Squeeze");
} else if (fsrReading < 800) {
Serial.println(" - Medium Squeeze");
} else {
Serial.println(" - Big Squeeze");
}
// Map the reading to LED brightness (Visual feedback)
int brightness = map(fsrReading, 0, 1023, 0, 255);
analogWrite(ledPin, brightness);
delay(100);
}