The cyber:bot robot's drive motors are called Continuous Rotation Servos. If you received your robot preassembled, these servos might need to be re-centered before moving on to navigation activities.
- If you just followed the directions in the Build your cyber:bot tutorial, you will have already centered your servos, and you can skip to the next page: Servo Direction
- If you were just given an assembled cyber:bot to use, the servos might need to be re-centered. Use the test below to find out.
Test if the servos are centered
Before running this test, double check the battery and servo connections.
- Make sure that the:
- Servos are plugged into the servo ports
- Battery pack is loaded with batteries
- Battery pack is plugged into the cyber:bot board
- The jumper is set for the type of batteries you are using
- Set the 3-position switch on the cyber:bot board to Position 1.
- Make sure the cyberbot.py module is added to the Project Files (see Add modules to your micro:bit).
- Enter and save both_servos_stay_still.py.
- Make sure to include the line from cyberbot import *.
- Flash both_servos_stay_still.py into your micro:bit.
# both_servos_stay_still.py from cyberbot import * bot(18).servo_speed(0) bot(19).servo_speed(0)
If a servo has not yet been centered, or if its center setting has drifted, it might turn, vibrate, or make a humming noise when your script tells it to stay still.
- Set the cyber:bot robot’s PWR switch to 2, to provide power to the servos.
- If both servos stay still, it means they are both centered, and you can skip to the next page: Servo Direction.
- Any servo that hums, vibrates, or turns in response to this test will need to be re-centered by following the instructions below.
If one or both servos need to be re-centered:
Tools You Might Need
If the Procedure checklist says to remove the servo from the cassis, use these tools that come in the cyber:bot Robot kit:
(1) Parallax screwdriver, or a different Phillips #1 point screwdriver with a 1/8″ (3.18 mm) or smaller shaft.
(1) Parallax Combination Wrench (#700-10025), or a 1/4" combination wrench.
- Check the part of the servo case where the 3-wire cable comes out. There should be a small round access hole very close to it.
- If that access hole is close to the battery pack, the servo will need to be disconnected from the chassis.
- Unscrew the screw in the center of the wheel.
- Pull the wheel away from the servo to pull it off the output shaft.
- Unscrew the four screws/nuts that hold the servo to the chassis.
- If the access hole is instead closer to the front of the cyber:bot, the servo will not need to be disconnected.
- Complete the Are the Servos Centered? activity, and come back here when you're done (and then continue to the next page).