Because the sun gear in a hybrid unit is pre-aligned within the servo motor gear reducers gearhead and not affixed to the motor 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 must be perfectly smooth; otherwise 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 really is difficult to consistently achieve smooth motion where the sun equipment is installed on the engine shaft. A good slight misalignment in sunlight gear (engine shaft runout or coupling inaccuracies) could cause rough procedure and noise.

Many servo controllers use software compensation, and their success depends upon knowing the lost movement of the whole system. This info is usually obtainable from the gearhead manufacturer.
Contouring applications usually involve end-effectors or tool-points that stick to mathematically defined paths. Sealant and bonding machines, water and flame cutters, laser beam welders and cutters, motion managed cameras, and CNC machine tools are good examples.

Software compensation is accomplished by commanding the motor to move beyond the apparently desired position by an amount add up to the system’s lost movement, thereby bringing the load 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 movement and the machine 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, thus compensating for the 0.1-in. lost motion.

Backlash is the excess space between two adjacent gear teeth and its engaging tooth; lost movement is the total looseness or movement at a reducer’s result shaft when the insight shaft is fixed. Dropped motion contains backlash, plus losses from bearing looseness, tolerances and suits, and shaft and gear tooth compliance.
Servo controllers can be programmed to compensate for backlash and lost movement in planetary gearheads. This system compensates for backlash also where an application requires accuracy better than the minimal backlash of the gearhead.