Because the sun equipment 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 an automobile. Motion of the nozzle as it follows 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 application.
Smooth motion, this means the absence of torque and velocity variations (ripple), is important in contouring applications. But, it is difficult to regularly achieve smooth movement where the sun equipment is installed on the electric motor shaft. Even a slight misalignment in sunlight gear (electric motor 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 movement of the servo gear reducer entire system. This details is usually offered from the gearhead producer.
Contouring applications usually involve end-effectors or tool-points that stick to mathematically defined paths. Sealant and bonding devices, drinking water and flame cutters, laser welders and cutters, movement managed cameras, and CNC machine equipment are good examples.
Software compensation is accomplished by commanding the engine 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 example, 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 system has 0.1-in. dropped motion, then your controller tells the motor to go 110,000 encoder counts to get 1.0 in. of motion, hence compensating for the 0.1-in. lost motion.
Backlash is the extra 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 input shaft is fixed. Lost motion contains backlash, plus losses from bearing looseness, tolerances and matches, and shaft and equipment tooth compliance.
Servo controllers can be programmed to pay for backlash and lost motion in planetary gearheads. This technique compensates for backlash also where a credit card applicatoin requires accuracy better than the minimal backlash of the gearhead.