Because the sun equipment in a hybrid unit is pre-aligned within the gearhead rather than affixed to the motor shaft, these gearheads can be used 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 window frame must be perfectly smooth; or else a ripple in velocity alters the bead diameter and causes messy glue program.

Smooth motion, this means the lack of torque and velocity variations (ripple), is important in contouring applications. But, it is difficult to regularly achieve smooth motion where the sun gear is mounted on the motor shaft. A good slight misalignment in sunlight gear (electric motor shaft runout or coupling inaccuracies) could cause rough operation and noise.

Many servo servo gear reducer controllers use software compensation, and their success depends upon knowing the lost motion of the entire system. This information is usually offered from the gearhead manufacturer.
Contouring applications generally involve end-effectors or tool-points that adhere to mathematically defined paths. Sealant and bonding devices, water and flame cutters, laser beam welders and cutters, motion controlled cameras, and CNC machine equipment are good examples.

Software compensation is accomplished by commanding the engine to move beyond the apparently desired position by an amount add up to the system’s dropped motion, thereby bringing the strain to the truly desired position. For instance, 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 machine has 0.1-in. dropped motion, then the controller tells the motor to move 110,000 encoder counts to get 1.0 in. of motion, therefore compensating for the 0.1-in. lost motion.

Backlash is the excess space between two adjacent equipment teeth and its engaging tooth; lost movement is the total looseness or movement at a reducer’s result shaft when the input shaft is fixed. Dropped motion includes backlash, plus losses from bearing looseness, tolerances and matches, and shaft and equipment tooth compliance.
Servo controllers can be programmed to compensate for backlash and dropped motion in planetary gearheads. This system compensates for backlash even where a credit card applicatoin requires accuracy better than the minimal backlash of the gearhead.