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 a car. Movement of the nozzle since it follows the seam between a windshield and its window frame should be perfectly smooth; otherwise a ripple in velocity alters the bead diameter and causes messy glue software.
Smooth motion, which means the lack 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 mounted on the engine shaft. Even a slight misalignment in sunlight gear (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 motion of the entire system. This info 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, drinking 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 add up to the system’s lost movement, thereby bringing the strain to the truly desired position. For example, 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. dropped motion, then the controller tells the engine 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 extra space between two adjacent gear teeth and its own engaging tooth; lost movement is 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 fits, and shaft and gear tooth compliance.
Servo controllers could be programmed to compensate for backlash and lost movement in servo gear reducer planetary gearheads. This technique compensates for backlash actually where a credit card applicatoin requires accuracy much better than the minimal backlash of the gearhead.