A typical car dashboard features several rotary selectors. Temperature, vents, blowers, and headlights are operated by rotating dial-type switches. Automotive manufacturers test these components to determine whether the torque required to operate them is within acceptable limits.
A selector can be neither too stiff nor too slack. If too stiff, the driver will struggle to operate it efficiently and safely; if too slack, selection will be uncertain and slippage could result. Rotary selectors must also provide definite tactile feedback, to provide indication of the selector's position when visual contact is a problem, such as when the vehicle is in motion and the driver cannot be distracted. Working from carefully derived ergonomics parameters, manufacturers define torque ranges for their selectors. Samples of the finished component will undergo testing as part of the quality control process. The test will obtain measurement of the torque required to rotate the selector, so the test device must emulate the human motions involved and capture an accurate picture of the selector's torque performance.