The Desktop RoboTurret is a Arduino based physical computing platform. This 2-Servo Robotic kit is a great introduction into the world of Arduino and robotics. The standard kit comes with a pushbutton and joystick for control, as well as a laser that can be mounted on the turret. Add-on kits allow control via a Wii nunchuk and vision tracking using a PC.
This guide will help you setup the hardware and software for the RobotGeek Desktop RoboTurret.
- Setting up the Arduino Software
- Centering your Servos
- RoboTurret Assembly
- Testing the Turret
- Controlling the Turret
- Demos and Projects
- RobotGeek 101
If you have not already set up your Geekduino/ Arduino compatible board, please see the Geekduino Getting Started Guide. This guide will assist you in getting set up with the Arduino software as well as install libraries and test sketches for the RoboTurret. Even if you do not have a Geekduino, you should follow through this guide to grab the test sketches you will be using throughout the RoboTurret getting started guide.
Servo motors act like robotic joints - you can set them to specific positions to move your robot to different positions. This means that the servo needs to be set to s specific position before assembling your robot, or it will not work correctly. We are going to 'center' the servos, setting them to halfway between their maximum and minimum position. To begin centering your servos, we're going to have to set up your test rig. This is incredibly easy to do with a RobotGeek Sensor Shield. Start by attaching your Sensor Shield to your Geekduino/Arduino Compatible board. Slot the bottom pins of the RobotGeek Sensor Shield into the terminals in the top of the Geekduino. Note how the boards seat evenly on top of each other, and the pins line up exactly. Be careful not to bend the pins.
|Device||Sensor Shield Port|
Jumpers and Power
RobotGeek servos must be powered by an external power supply like the 7v5A power supply included with your kit. If you have servos plugged in to the shield and do not have the external power supply plugged into your Geekduino you will see erratic behavior.
You will also need to adjust your shield to make sure the power is getting to the servos correctly. Make sure that you have both of the jumpers on the Sensor Shield set to Voltage In (VIN) If you would like more information about this, check out the Jumpers/Power section of the RobotGeek 101 learning series.
The following code will set any servos on pins 10 or 11 to a centered position (90°).
This code will both test and center your servos. Each servo will move do 45 degrees, 125 degrees, then 90 degrees. If you want to restart the movement, just push the reset button on your Geekduino. Make sure to only run this code when nothing is attached to your servos. Running this code on an assembled robot could damage the robot or servos.
File > Sketchbook > RobotGeek sketches > Tools > centerServo
If you cannot find this sketch, make sure you have setup your Libraries in the Geekduino Getting Started Guide. You can load this code using the same method as you used to load your test code on the Geekduino Getting Started Guide.
Installing Servo Horns
Once the RobotGeek Servos have stopped moving, they are centered and you can install the servo horn. To line up the horn, place it with the notch facing up. If it does not slide on easily, or it clicks into place with the holes not facing cardinal directions, ignore the notch, remove the horn, rotate it about 45 degrees and try again. Repeat until the top and bottom holes are aligned as close to exactly North and South of the center, as shown.
Warning: Do not rotate the center shaft during this process. This was aligned when you ran the centerServo tool in the above step.
Your servos don't need to be 'perfectly' aligned, but the closer you can get, the better the robot will operate. Once your horn is ready, use a black phillips bolt included with the horn to secure the horn to the servo.
One of your RobotGeek servos will also need an idler horn. Idler horns are passive horns on the opposite side of the main servo horn. The idler horn allows you to connect a hinge bracket to the servo. The remaining one servo will not need an idler horn.
Install the idler horn on the back of the servo and secure it with the silver screw. Orientation on the idler horn does not matter.
If you'd like more information on centering servos, see this page for more information and a video on centering servos.