Because the sun equipment in a hybrid unit is pre-aligned within the gearhead rather than affixed to the engine shaft, these gearheads can be used in contouring applications such as 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; or else a ripple in velocity alters the bead diameter and causes messy glue app.
Smooth motion, which 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 electric motor shaft. Even a slight misalignment in the sun gear (engine shaft runout or coupling inaccuracies) can cause rough procedure and noise.
Many servo controllers use software compensation, and their success depends on knowing the lost motion of the whole system. This information is usually offered from the gearhead producer.
Contouring applications usually involve end-effectors or tool-points that adhere to mathematically defined paths. Sealant and bonding devices, water and flame cutters, laser welders and cutters, movement managed cameras, and CNC machine tools are good examples.
Software compensation is achieved by commanding the electric motor to move beyond the apparently desired position by a quantity add up to the system’s dropped movement, thereby bringing the strain to the truly desired position. For instance, consider a servomotor, gearhead, and leadscrew combination in a pick-andplace robot. If 100,000 encoder counts equals 1.0 in. of linear movement 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 movement at a reducer’s output shaft when the insight shaft is fixed. Dropped motion includes backlash, plus losses from bearing looseness, tolerances and matches, and shaft and gear tooth compliance.
Servo controllers could be programmed to compensate for backlash and lost motion in planetary gearheads. This servo motor gear reducers technique compensates for backlash even where an application requires accuracy better than the minimal backlash of the gearhead.