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 such as a glue-dispensing nozzle for affixing a windshield to an automobile. Motion of the nozzle as it comes after 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, which means the absence 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) can cause rough servo motor gear reducers procedure and noise.
Many servo controllers use software compensation, and their success depends upon knowing the lost movement of the entire 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 devices, water and flame cutters, laser welders and cutters, motion managed cameras, and CNC machine tools are good examples.
Software compensation is achieved by commanding the engine to move beyond the apparently desired position by a quantity equal to the system’s dropped movement, 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 system has 0.1-in. dropped motion, then your controller tells the engine to move 110,000 encoder counts to obtain 1.0 in. of motion, thus compensating for the 0.1-in. lost motion.
Backlash is the excess space between two adjacent equipment teeth and its own engaging tooth; lost motion may be the total looseness or movement at a reducer’s output 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 lost motion in planetary gearheads. This system compensates for backlash also where a credit card applicatoin requires accuracy much better than the minimal backlash of the gearhead.
