Because the sun gear in a hybrid unit is pre-aligned within the gearhead rather than affixed to the engine shaft, these gearheads can be utilized in contouring applications like a glue-dispensing nozzle for affixing a windshield to an automobile. Motion of the nozzle since it follows the seam between a windshield and its window frame should be perfectly smooth; otherwise a ripple in velocity alters the bead diameter and causes messy glue software.
Smooth motion, this means the absence of torque and velocity variations (ripple), is important in contouring applications. But, it is difficult to consistently achieve smooth motion where the sun equipment is mounted on the engine 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 movement of the whole system. This details is usually obtainable from the gearhead manufacturer.
Contouring applications generally involve end-effectors or tool-points that stick to mathematically defined paths. Sealant and bonding devices, 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 motor to move servo gear reducer beyond the apparently desired position by an amount equal to the system’s dropped motion, thereby bringing the strain to the truly desired position. For example, look at a servomotor, gearhead, and leadscrew combination 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 your controller tells the 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 excess space between two adjacent equipment teeth and its engaging tooth; lost motion may be the total looseness or motion at a reducer’s output shaft when the insight shaft is fixed. Lost motion includes backlash, plus losses from bearing looseness, tolerances and matches, and shaft and equipment tooth compliance.
Servo controllers 
can be programmed to pay for backlash and lost motion in planetary gearheads. This system compensates for backlash even where an application requires accuracy much better than the minimal backlash of the gearhead.