Because the sun gear in a hybrid unit is pre-aligned within the gearhead and not 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 follows the seam between a windshield and its window frame should be perfectly smooth; or else a ripple in velocity alters the bead diameter and causes messy glue software.
Smooth motion, this means the lack of torque and velocity variations (ripple), is important in contouring applications. But, it is difficult to consistently achieve smooth motion where the sun gear is installed on the electric motor shaft. A good slight misalignment in the sun gear (electric motor shaft runout or coupling inaccuracies) could cause rough servo motor gear reducers procedure and noise.
Many servo controllers use software compensation, and their success depends on knowing the lost movement of the entire system. This info is usually obtainable from the gearhead manufacturer.
Contouring applications generally involve end-effectors or tool-points that follow mathematically defined paths. Sealant and bonding devices, drinking water and flame cutters, laser welders and cutters, motion managed cameras, and CNC machine tools are good examples.
Software compensation is accomplished by commanding the engine to move beyond the apparently desired position by a quantity add up to the system’s dropped motion, thereby bringing the strain to the truly desired position. For instance, look at a servomotor, gearhead, and leadscrew mixture in a pick-andplace robot. If 100,000 encoder counts equals 1.0 in. of linear movement and the machine has 0.1-in. lost motion, then the controller tells the electric motor to move 110,000 encoder counts to get 1.0 in. of motion, hence compensating for the 0.1-in. lost motion.
Backlash is the excess space between two adjacent equipment teeth and its own engaging tooth; lost movement may be the total looseness or movement at a reducer’s result shaft when the 
insight shaft is fixed. Lost motion includes backlash, plus losses from bearing looseness, tolerances and matches, and shaft and gear tooth compliance.
Servo controllers can be programmed to pay for backlash and lost movement in planetary gearheads. This technique compensates for backlash actually where a credit card applicatoin requires accuracy much better than the minimal backlash of the gearhead.