What Is a Servo Motor?
A servo motor is a closed-loop system that combines a motor, a position sensor and a control circuit; it precisely holds the desired position with feedback.
How Does It Work?
The sensor inside it (a pot or encoder) measures the actual position; the control circuit compares this with the target position and drives the motor until no error remains. This is the "closed-loop" logic.
Closed vs Open Loop
A stepper motor is open-loop; if it skips a step under load it doesn't notice. A servo, measuring continuously, corrects the deviation; it holds the target position even if the load increases.
| Property | Servo |
|---|---|
| Control | Closed loop |
| Feedback | Pot / encoder |
| Advantage | Corrects error, precise |
RC Servo
RC servos used in hobby/robotics take an angle from the PWM pulse width (e.g. ~1–2 ms pulse → 0–180°). They're easily controlled by an MCU with a single signal wire.
Where Is It Used?
Robot arms, CNC, industrial automation, RC vehicles, camera gimbals and systems needing precise/under-load positioning.
Torque and Precision
Because servos hold their position even under load, they offer high holding torque and repeatability; this is the main advantage that separates industrial servos and RC servos from cheap stepper solutions.
Common Mistakes
- Power line: feeding the servo current from the MCU causes a voltage drop.
- Signal noise: jittery PWM jitter in an RC servo causes wobble.
- Mechanical limit: forcing an RC servo past its limit angle breaks the gear.
Frequently Asked Questions
Why is a servo precise?+
How is an RC servo controlled?+
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