#piwars

To PiWars or not to PiWars

It was back in 2014 that a small group of us from Ipswich Makerspace came together and entered the first PiWars competition held in Cambridge. It turned out quite well and we won our category, under £75. The robot shown was one of our prizes, now enhanced with several years of dust.

Fast forward a few years and we have now competed in all four of the PiWars competitions, coming runner up in two and winning two. The last win, by just one point separating us from second place contestant [Brian Corteil](https://coretecrobotics.co.uk/).

It is great fun competing, and I always learn lots whilst preparing the robot, however it is hard work and takes all my spare time for about half a year in the lead up to the competition. So I have been thinking hard about whether to compete again in 2019. The competition is always heavily over subscribed, so I thought by not entering would give someone else an opportunity to compete.

Hi Today we were working on distance. Distance sensing actually. We now have traction* and not the previous slabs of ice.

*"traction" is blue tack.

Now the robot can move fowards of there is distance away and backwards if there is not so we are close to being able to do most of the projects.

For us we were putting a storm into our brains which made us think of some illyd stuff until we eventually came up with ideas for what we shall do in oure video - it is going to be very creepy.

As the day comes to an end, 💩 and 🕳️ dicuss odd things, I do this and 🐙 and 💣code because that is probably important.

yeah - that is it . Probably important.

🥞

code

Lets get some code on this thing

So now we have the electronics sorted, lets have a look at the code. I’m borrowing heavily from this resource. I chose to use this code since the project was very well documented with some nice videos. The code also uses the same gyroscope as me. One downside is that this code is designed for stepper motors and I’m using cheap DC motors.

Before I jumped into the main code, I created a quick script just to check the motors were working. I created a few functions and ran them to ensure the motors moved correctly. If you look at this code you can also see how I am using the input pins of the motor driver to set direction and the enable pin with PWM to set the speed.

/* * Drive Motors with an Arduino Mini Pro using an L239D 'H' bridge * Keith Ellis * July 2018 * */ #define motor_left_A 2 // Motor Left Pin A - High = forward #define motor_left_B 4 // Motor Left Pin B - High = reverse #define motor_left_En 3 // Motor Left Enable Pin, PWM on this pin will control speed #define motor_right_A 5 // Motor Right Pin A - High = forward #define motor_right_B 7 // Motor Right Pin B - High = reverse #define motor_right_En 6 // Motor Right Enable Pin, PWM on this pin will control speed void setup() { pinMode(motor_left_A, OUTPUT); pinMode(motor_left_B, OUTPUT); pinMode(motor_left_En, OUTPUT); pinMode(motor_right_A, OUTPUT); pinMode(motor_right_B, OUTPUT); pinMode(motor_right_En, OUTPUT); } void loop() { AllMotorsFwd(127); // Speed from 0 - 255 delay(100); AllMotorsRev(255); delay(75); AllMotorsFwd(127); delay(100); AllMotorsRev(255); delay(120); AllMotorsFwd(127); delay(50); AllMotorsRev(255); delay(75); AllMotorsFwd(127); delay(100); AllMotorsRev(127); delay(125); } void LeftMotorFwd(int speed){ //Speed is int from 0 - 255 digitalWrite(motor_left_A, HIGH); digitalWrite(motor_left_B, LOW); analogWrite(motor_left_En, speed); } void LeftMotorRev(int speed){ //Speed is int from 0 - 255 digitalWrite(motor_left_A, LOW); digitalWrite(motor_left_B, HIGH); analogWrite(motor_left_En, speed); } void RightMotorFwd(int speed){ //Speed is int from 0 - 255 digitalWrite(motor_right_A, HIGH); digitalWrite(motor_right_B, LOW); analogWrite(motor_right_En, speed); } void RightMotorRev(int speed){ //Speed is int from 0 - 255 digitalWrite(motor_right_A, LOW); digitalWrite(motor_right_B, HIGH); analogWrite(motor_right_En, speed); } void AllMotorsFwd(int speed){ //Speed is int from 0 - 255 LeftMotorFwd(speed); RightMotorFwd(speed); } void AllMotorsRev(int speed){ //Speed is int from 0 - 255 LeftMotorRev(speed); RightMotorRev(speed); } void LeftMotorStop(void){ digitalWrite(motor_left_A, LOW); digitalWrite(motor_left_B, LOW); digitalWrite(motor_left_En, LOW); } void RightMotorStop(void){ digitalWrite(motor_right_A, LOW); digitalWrite(motor_right_B, LOW); digitalWrite(motor_right_En, LOW); } void AllMotorsStop(void){ LeftMotorStop(); RightMotorStop(); }

This worked as planned, you can download this code here

After editing the Balance Bot code to take out references to the stepped motors and copying in my motor functions I ended up with the code here.

Before running this code, the balance point of the robot needs to be determined. This can be done by running the calibration code here Balnce the robot upright and open the serial console. Make a note of the Balance value and paste it into the variable acc_calibration_value on line 17 of the main Balance_robot.ino code.

Today we managed to connect a controller to our robot via bluetooth. Basically, at 1 pm 🐼 came in saying we can now use and control the robot through the use of Blue Dot which is an online controller app which can be on a phone of tablet. Very quickly, our previous scripts worked and no new version of python was needed.

Using a circle to control the robot, it could move quickly in a not-ish straight line (it is currently being fixed). Theres only one week left until the competition and only me and 💩 were here today, the video is yet to be made and not many are thought to be here next week so we have a lot of work and 3 hours to do it.

Today we got the green screen and practiced filmed the first 4 scenes.

This was our recording studio for secne 4, minus the table and add other props for other scenes. In a science classroom 🤨.

The other people updated python and got the nescessary libraries for the controller inputs.

There are seven challenges at the in-person event for PiWars 2024, each with their own problems to solve. They are split in to three categories: Autonomous only, Autonomous/Remote, Remote Only. For the second of those, if you are in the Advanced/Professional category you have to attempt the challenge autonomously. State of the Onion NE-Five exists as a robot, the base hardware is all there and…