How to find the right Robot Parts AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Robot Parts
- Servo torque margin
- Calculate the joint torque (load times lever arm) and choose a servo whose rated torque at your voltage is about twice that figure. Servos running near their stall torque overheat, jitter and strip gears.
- Servo type and protocol
- Standard hobby servos take a 50 Hz PWM pulse of roughly 1 to 2 ms. Bus servos (Dynamixel, Feetech, Hiwonder) need the matching TTL or RS-485 interface, protocol and baud rate. Bus servos give position feedback and daisy-chaining, but they cannot be driven like PWM servos, and vendors' protocols differ.
- Servo spline and horns
- Match the output spline count to your horns and brackets. Futaba-style servos commonly use 25T and Hitec-style use 24T, but verify for each model. Mismatched splines strip under load or will not fit.
- Motor driver rating
- The driver's continuous current must exceed the motor's stall current, and its voltage range must cover your battery. Prefer MOSFET drivers over L298N-class bipolar drivers. Bipolar drivers lose a couple of volts as heat, and undersized drivers fail at stall.
- Gearmotor and encoder spec
- Choose the gear ratio from the target wheel speed and torque. If you need closed-loop speed or position control, get motors with encoders. Without encoders, driving straight and odometry are unreliable.
- Shaft and hub fit
- Match the shaft diameter and profile (round, D-shaft, hex) to the wheel hubs and couplers. Shaft mismatch is the most common reason wheels and couplers do not fit.
Brands that matter
- ROBOTIS: Dynamixel bus servos with feedback, documented protocol and brackets.
- Feetech: Low-cost serial bus servos and PWM servos.
- Pololu: Micro metal gearmotors, encoders, MOSFET motor drivers and hubs.
- Hitec: Established hobby servo maker with published specs.
- Savox: High-torque digital and high-voltage servos.
- Adafruit: PCA9685 servo driver boards and motor driver breakouts.
- Waveshare: Bus servo driver boards and Raspberry Pi motor HATs.
What to avoid
- Unbranded SG90 or MG996R clones for load-bearing joints, because quality and real torque vary widely.
- L298N driver modules in battery-powered builds where voltage drop and heat matter.
- Servos listed with torque but no stated test voltage.
- Running high-voltage servos and standard servos from the same supply rail.
Questions
Analog or digital servo?
Digital servos hold position more firmly and respond faster but draw more current. Both use the same PWM signal, so the choice mostly affects power sizing.