PiDER 3.0

31st March 2019

31st March 2019

20th March 2019

Final look under the hood

All the wiring is complete and not likely to change anytime soon. An attachment connector has been added to the rear motor chassis for the extra flashy surprise that I added today. It is totally unnecessary but it looks good :-)

16th March 2019

Colour Calibration

14th March 2019

5 Barrel Nerf Shooter

This is my solution to firing five projectiles at space invaders. Sorry but the mechanism is secret until the competition, which is why there is a cloth over it. I’m still undecided if I shall leave the mechanism exposed to view or 3D print a cover for it. 

25th February 2019

Line Following with a Pi Camera

Line Following with the Pi Camera.

23rd February 2019

Sample Holder

I decided to make the ‘Sample Holder’ for the Spirit of Curiosity challenge with my 3D printer. I know it is not essential to do this, but I want to practice driving over bumpy terrain with different size, weight and shape samples to see how likely it is that a sample will be lost on route. Or if my attachment panel is unable to cope with heavy samples.

The Sample holder is printed in two parts and then glued together, enabling the 3mm wire post to easily be made captive within the structure. The 3mm wire is the type that is often used to hold up chain link fencing.

21st February 2019

Automatically running your robot’s Python code at boot.

I always use an intermediate bash script to run my Python code because I find it more convenient to modify the location and file name or disable the auto load. This is a quick description of how I have set it up for my PiDER 3.0 robot. You can use this set up, but modify it to your chosen location and file name.

First of all, create a Bash script called ‘RunAtBoot.sh’ and save it in the home folder. You can name it whatever you like but this is what I used. This is the script that it contains. Folder & file names should NOT contain spaces.

#!/bin/sh cd /home/pi/AppDir sudo python scriptname.py &

‘AppDir’ is the directory of your code and ‘scriptname.py’ is the name of your robot’s Python script. Now make the ‘RunAtBoot.sh’ executable. Open the console window and enter the following line.

chmod  +x RunAtBoot.sh

Now using nano in the console, modify the boot profile

sudo nano /etc/profile

Scroll to the bottom of the script and add the following line. Remember to include the ‘&’ at the end to allow the rest of the system processes to run as normal.

/home/pi/RunAtBoot.sh &

Save and close. Now, if you got everything right, the robot code will auto-load every time you boot up. Because the Python runs in the background it is a good idea to have a way of terminating the Robot’s Python script, by means of a combination of buttons pressed together on the controller to free the system resources. You might want to do this to enable a bug fix or colour calibration and then a re-run without the need to reboot. When my Robot’s script terminates, it runs some clean up code before it Exits. Your Python script should do something similar to the following.

output.close()              # Close the RGB array object camera.close()            # Close the Camera object exitScreen()                # Send 'EXIT' message to controller screen GPIO.cleanup()          # Clean up the GPIO exit()                           # Exit the Python interpreter

20th February 2019

Peripherals board tour

20th February 2019

14th February 2019

More testing. The ‘Hubble Telescope Nebula Challenge’ in this picture. This particular arena has took quite a lot of use, as you can see by the rotation area in the centre.

14th February 2019

The Canyons of Mars challenge