Stepper Motors

It depends on the application. Steppers are cost-effective, offer excellent low-speed torque, and are easier to control for stable loads. Servos are better for high-speed, dynamic loads where efficiency and feedback are critical. For standard warehouse AGVs moving at moderate speeds, steppers are often the superior value choice.

Missed steps occur when the load torque exceeds the motor's pull-out torque, causing the rotor to lag behind the magnetic field. This is usually caused by accelerating too quickly or hitting an obstacle. To prevent this, implement S-curve acceleration ramps in your code and ensure the motor is sized with a 30-50% torque safety margin.

Unlike DC motors, steppers draw full current at standstill to maintain holding torque. This constant current generates heat. To mitigate this, use "current reduction" or "standby" features in your driver, which lower the current (e.g., to 50%) when the motor is idle for more than a few milliseconds.

Often, yes. While steppers have high torque, direct-driving wheels can be inefficient for heavier robots. A planetary gearbox increases torque output and resolution while dampening vibration. A 5:1 or 10:1 ratio is common for mobile robots to balance speed and towing capacity.

Bipolar motors (4 wires) use the full coil winding, offering significantly higher torque (about 30-40% more) than Unipolar motors (5, 6, or 8 wires). Bipolar requires a more complex H-bridge driver, but it is the industry standard for modern robotics due to the torque efficiency.

Microstepping is primarily for smoothness and resonance reduction, not necessarily accuracy. While 1/16 microstepping increases the theoretical resolution, the incremental torque between microsteps is small. Friction can prevent the motor from achieving the exact micro-position. Rely on full steps for guaranteed accuracy.

For light loads (under 10kg), NEMA 17 is sufficient. For medium warehouse robots (up to 50kg), NEMA 23 is the standard workhorse. For heavy industrial pallet movers, NEMA 34 or NEMA 42 motors are required to generate the necessary torque to overcome inertia and rolling resistance.

Yes. "Closed-loop steppers" or "hybrid steppers" include an encoder on the back of the motor. The driver compares the commanded steps to the actual position. If the motor stalls or misses steps, the driver compensates immediately. This offers the best of both worlds: stepper torque with servo reliability.

Higher voltage allows the current to rise faster in the coils, which improves high-speed performance. If your AGV needs to move quickly, running a 3.5V rated motor at 24V or 48V (with a chopper driver) is essential to maintain torque at speed.

Standard steppers are open and not waterproof (IP40). For AGVs operating in washdown areas or outdoors, you must purchase IP65 or IP67 rated stepper motors which feature sealed housings, waterproof connectors, and specialized shaft seals to prevent corrosion.

Every stepper has a natural resonant frequency. Operating at this specific speed causes excessive vibration and noise, potentially leading to stalling. To fix this, avoid the resonant speed range in your software, increase microstepping, or add a mechanical damper to the motor shaft.

Calculate the total current draw of all motors (Amps per phase × 2 phases). Since steppers draw current continuously, multiply this by your operating voltage to get Wattage, then divide your battery capacity (Wh) by the total Wattage. Remember that steppers are less efficient than DC motors, so battery sizing is critical.