Because the sun equipment in a hybrid unit is pre-aligned within the gearhead and not affixed to the electric motor shaft, these gearheads can be utilized in contouring applications such as a glue-dispensing nozzle for affixing a windshield to a car. Motion of the nozzle as 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 program.
Smooth motion, which means the absence of torque and velocity variations (ripple), is essential in contouring applications. But, it really is difficult to regularly achieve smooth motion where the sun gear is installed on the engine shaft. A good slight misalignment in the sun gear (motor shaft runout or coupling inaccuracies) could cause rough procedure and noise.
Many servo controllers use software compensation, and their success depends on knowing the lost movement of the whole system. This info is usually offered from the gearhead manufacturer.
Contouring applications usually involve end-effectors or tool-points that follow mathematically defined paths. Sealant and bonding devices, drinking water and flame cutters, laser beam welders and cutters, movement 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 an amount equal to the system’s lost motion, 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 servo motor gear reducers linear movement and the machine has 0.1-in. lost motion, then the controller tells the motor to move 110,000 encoder counts to obtain 1.0 in. of motion, hence compensating for the 0.1-in. lost motion.
Backlash is the excess space between two adjacent gear teeth and its own engaging tooth; lost movement is the total looseness or movement at a reducer’s result shaft when the insight shaft is fixed. Lost motion includes backlash, plus losses from bearing looseness, tolerances and suits, and shaft and gear tooth compliance.
Servo controllers could be programmed to pay for backlash and dropped movement in planetary gearheads. This technique compensates for backlash even where a credit card applicatoin requires accuracy better than the minimal backlash of the gearhead.