servo gear reducer

Because the sun equipment in a hybrid unit is pre-aligned within the gearhead rather than affixed to the motor shaft, these gearheads can be used in contouring applications like a glue-dispensing nozzle for affixing a windshield to an automobile. Motion of the nozzle since it comes after the seam between a windshield and its own 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 movement where the sun gear is mounted on the motor shaft. Even a slight misalignment in sunlight gear (electric motor shaft runout or coupling inaccuracies) could cause rough operation and noise.

Many servo controllers use software compensation, and their success depends upon knowing the lost motion of the whole servo gear reducer system. This info is usually available from the gearhead producer.
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 equipment are good examples.

Software compensation is achieved by commanding the engine to go beyond the apparently desired position by an amount 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 combination in a pick-andplace robot. If 100,000 encoder counts equals 1.0 in. of linear movement and the machine has 0.1-in. dropped motion, then the controller tells the electric motor 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 extra space between two adjacent gear teeth and its engaging tooth; lost movement is the total looseness or movement at a reducer's output shaft when the input shaft is fixed. Dropped motion contains backlash, plus losses from bearing looseness, tolerances and fits, and shaft and equipment tooth compliance.
Servo controllers can be programmed to compensate for backlash and dropped movement in planetary gearheads. This technique compensates for backlash actually where an application requires accuracy better than the minimal backlash of the gearhead.