![2018-04-06 15.39.00.jpg](https://steemitimages.com/DQmNrZCmQYvfJbvTwMaY3mGzkBVRgy4h1ed46YmHgBDAyVh/2018-04-06%2015.39.00.jpg)

Previously we looked at [motor control](https://steemit.com/programming/@makerhacks/raspberry-pi-robots-with-python) but for our robot there is another type of *actuator* that we need to drive, and those are ***Servos***.

### Servos

Servos are another kind of motor, but they are actually easier to use than regular motors with the Pi, because they have built-in controllers. There is one problem, however, which we will get to in a moment.

We can choose between the regular kind of servo, where the servo can be told to move to a position or angle, and then there are the continuous kind where instead of angle, the same instruction controls speed and direction.

### Problem?

Rather than tell you about it, let me show you :)

Wire up a servo with the power connected to 5v, the ground connected to a GND, and the signal connected to Pin 18.

We will be using the chips pin numbers so refer to the Pinout.xyz guide here:

https://pinout.xyz/resources/raspberry-pi-pinout.png

```
from gpiozero import AngularServo
from time import sleep

servo = AngularServo(18, min_angle=-42, max_angle=44)
while True:
    servo.min()
    sleep(1)
    servo.mid()
    sleep(1)
    servo.max()
    sleep(1)
    servo.angle = 40
    sleep(1)
    servo.angle = 20
    sleep(1)
    servo.angle = 0
    sleep(1)
    servo.angle = -20
    sleep(1)
    servo.angle = -40

```

This code will *work* but ill likely find the motion is stuttery.  This is because of the Raspberry Pi being a fully-fledged computer rather than a microcontroller. Instead of just doing one thing at a time, the Pi has a multi-tasking operating system that has to do many things all at once.  

https://youtu.be/bGiFAjs9IMQ

### Raspberry Pi Jitter Solution

Fortunately for us, a [generous soul from the UK has ported a low-level library](http://abyz.me.uk/rpi/pigpio/index.html) for us to use. 

```sudo pip3 pigpio```

and run ```sudo pigpiod```

Add the following code then check out the difference:

```
import pigpio
from time import sleep

# connect to the 
pi = pigpio.pi()

# loop forever
while True:

    pi.set_servo_pulsewidth(18, 0)    # off
    sleep(1)
    pi.set_servo_pulsewidth(18, 1000) # position anti-clockwise
    sleep(1)
    pi.set_servo_pulsewidth(18, 1500) # middle
    sleep(1)
    pi.set_servo_pulsewidth(18, 2000) # position clockwise
    sleep(1)
```

Much more stable, right?

### What now?

As we have seen, other than the power limitations, the Pi can be a capable ***physical computing*** device, but for anything more in-depth I like to split the responsibilities of hardware control versus processing. 

#### Check out my article where I [combine the Raspberry Pi *and* Arduino](https://steemit.com/arduino/@makerhacks/runningraspberrypiandarduinoforthebestofbothworlds-2t2sectslz).