Because the sun equipment in a hybrid unit is pre-aligned within the gearhead rather than affixed to the engine shaft, these gearheads can be utilized in contouring applications like a glue-dispensing nozzle for affixing a windshield to an automobile. Movement of the nozzle as it comes after 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 application.
Smooth motion, which means the absence of torque and velocity variations (ripple), is important in contouring applications. But, it is difficult to servo motor gear reducers consistently achieve smooth movement where the sun gear is installed on the electric motor shaft. A good 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 movement of the entire system. This details is usually available from the gearhead manufacturer.
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 beam welders and cutters, motion controlled cameras, and CNC machine tools are good examples.
Software compensation is accomplished by commanding the electric motor to move beyond the apparently desired position by a quantity add up to the system’s lost motion, thereby bringing the load to the truly desired position. For instance, look at 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 electric motor to go 110,000 encoder counts to obtain 1.0 in. of motion, therefore compensating for the 0.1-in. lost motion.
Backlash is the excess space between two adjacent equipment teeth and its engaging tooth; lost movement may be 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 matches, and shaft and gear tooth compliance.
Servo controllers could be programmed to pay for backlash and dropped movement in planetary gearheads. This system compensates for backlash also where an application requires accuracy much better than the minimal backlash of the gearhead.