Strain Gauge

A small element bonded to metal whose electrical resistance changes as it deforms, the basic building block of force sensors.

A strain gauge is a sensing element that converts a tiny deformation into a change in electrical resistance, typically a metal foil grid or semiconductor pattern printed on an insulating backing. Bonded to the surface of an elastic structure, it stretches or compresses slightly as the structure is loaded, changing its resistance, which is then read out with a Wheatstone bridge — a circuit that amplifies a small resistance change into a voltage signal. Six-axis force/torque sensors, joint torque sensors, foot-force sensors, and load cells are mostly built on strain gauges: several are bonded to a specially designed elastic structure, and the forces and torques along each axis are computed from their combined readings. Strain gauges are accurate and low-cost, but sensitive to temperature and subject to zero drift, requiring temperature compensation and periodic recalibration.

ExampleInside a six-axis force/torque sensor mounted on an arm’s wrist, several groups of strain gauges are bonded to a cross-beam elastic structure to measure force and torque along three axes each.

Also called

Resistive Strain Gauge, Strain-Gauge Force Sensing

Related

Six-Axis Force/Torque Sensor · Joint Torque Sensor · Foot Force Sensor · Sensor Drift · Crosstalk (Inter-Axis Coupling)

Sources

Strain gauge - Wikipedia