Robotics
Backlash
ActivePublished
Key
innovation
Naming and framing the lost motion at direction reversal as a key limit on precision and force control.
Category
Robotics
Abstraction level
Primitive
Operation level
Robot control
How it works
On a direction change, the motor must first 'take up' the play before it starts moving the output, creating a dead zone in the response. It is reduced by design (low-backlash harmonic/strain-wave or cycloidal gears, direct-drive/QDD) or compensated in control.
Problem solved
Precise joint position and force control requires motor motion to faithfully map to output motion; backlash breaks this relationship at every direction reversal.