Details : MCU + peripherals¶
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Basics on servo¶
- Types :
- Closed-loop : 180-degree servo motor has a mechanical pin that prevents it from rotating beyond 180 degrees
- Open-loop : Allows 360 degrees rotation
- Torque per centimeter : Force a servo can apply at a certain distance from the pivot point :
- Stall : Maximum torque a servo can provide before it cannot rotate further
- This increases with voltage
Torque per centimeter (torque/cm) is a measure of the force a servo can apply at a certain distance from the pivot point.
Stall torque refers to the maximum torque a servo can provide before it cannot rotate further due to insufficient force.
Increasing the voltage applied to the motor generally increases its rotation speed. The operating speed of a servo is usually measured in degrees per second.
PWM (Pulse Width Modulation) signals are sent to the servo every 20 milliseconds, which corresponds to 50 pulses per second (50 Hz). The width of the pulse determines the servo angle: a wider pulse moves the servo to the left, while a shorter pulse moves it to the right.
Inside the servo, a potentiometer provides feedback: it increases or decreases resistance depending on the shaft position. The servo compares the voltage from the potentiometer with the incoming PWM signal to adjust the motor and reach the desired angle.
In general, a larger servo motor requires a larger gear and a bigger motor to provide more torque and handle heavier loads.
usually the 180 degree one has a pin that stops it rotating more than 180 degrees (close loop) Some doesn't have this so can rotate 360 degrees (open loop)
About torque/cm
Stall torque : unable to provide sufficient force The higher the voltage applied, the faster it would rotate operating speed degrees of rotation
pwm are pulses that are sent every 20 milliseconds or 50 pulses per second = 50 Hz If wide pulse go to the left if short pulse go to the right Can change the angle just based on the width of the pulse
Potentiometer increases or reduces resistance and so the voltage from the potentiometer is compared with the pwm?
Bigger motor means bigger gear and motor
| Feature | Servo Motor | Stepper Motor | DC Motor |
|---|---|---|---|
| Motion Control | Precise angle control | Stepwise incremental rotation | Continuous rotation, speed control |
| Feedback | Built-in (potentiometer) | Usually open-loop; optional encoder | Usually none; optional encoder |
| Rotation Range | Limited (0°–180° / 360°) | Can rotate continuously | Can rotate continuously |
| Control Signal | PWM from MCU | Step pulses from MCU/driver | Voltage or PWM |