Because the sun gear in a hybrid unit is pre-aligned within the gearhead and not affixed to the engine shaft, these gearheads can be utilized in contouring applications like a glue-dispensing nozzle for affixing a windshield to a car. Motion of the nozzle as it comes after the seam between a windshield and its own window frame must be perfectly smooth; or else a ripple in velocity alters the bead diameter and causes messy glue application.

Smooth motion, which means the absence of torque and velocity variations (ripple), is servo motor gear reducers important in contouring applications. But, it is difficult to regularly achieve smooth movement where the sun equipment is installed on the electric motor shaft. Even a slight misalignment in sunlight gear (engine shaft runout or coupling inaccuracies) can cause rough operation and noise.

Many servo controllers use software compensation, and their success depends upon knowing the lost motion of the whole system. This info is usually offered from the gearhead producer.
Contouring applications generally involve end-effectors or tool-points that adhere to mathematically defined paths. Sealant and bonding machines, drinking water and flame cutters, laser welders and cutters, motion managed cameras, and CNC machine equipment are good examples.

Software compensation is accomplished by commanding the electric motor to move beyond the apparently desired position by a quantity add up to the system’s lost motion, thereby bringing the strain to the truly desired position. For example, consider a servomotor, gearhead, and leadscrew mixture in a pick-andplace robot. If 100,000 encoder counts equals 1.0 in. of linear motion and the system has 0.1-in. lost motion, then the controller tells the electric motor to go 110,000 encoder counts to get 1.0 in. of motion, therefore compensating for the 0.1-in. lost motion.

Backlash is the extra space between two adjacent gear teeth and its engaging tooth; lost movement is the total looseness or motion at a reducer’s result shaft when the insight shaft is fixed. Lost motion includes backlash, plus losses from bearing looseness, tolerances and fits, and shaft and equipment tooth compliance.
Servo controllers can be programmed to pay for backlash and dropped motion in planetary gearheads. This technique compensates for backlash actually where an application requires accuracy better than the minimal backlash of the gearhead.