PiWars 2021 Challenge Runs

 Arena

 The arena is 1500x1500mm and is made using wooden doors and wooden planks.

Illustration 1 - Arena

  Feed The Fish

This challenge requires a special fish bowl, that was build with LEGO and has motors to animate three Evangelion fishes. It is known that the Evangelion fishes need a lot of food to grow up, and can get quite big ;)

Illustration 2 - Fish Bowl

The challenge was attempted with the spring loaded 6mm gun, but the gun was choosen in 2019 to knock down cardboard targets because it's as safe as nerf but arc a lot less, and feeding the fish with pellets require the bullet to arc at least a little.

The successfull attempt was made using the ball method and remote controls. OrangeBot achieves an unremarkable 4 balls score in three runs. Using an hill like arena is an extra challenge.



Video 1 - Feed The Fish Submission.

Tidy Up The Toys

This challenge requires small 50mm cube props, and an elevator attachment is used to move them from original position to destination in a given order.

Remote controls and side by sides cubes were used. The elevator didn't have the hight requirement to stack them up.

Illustration 3 - Cube Construction



Video 2 - Tidy up The Toys Submission

Up The Garden path

A simple path to be traversed using remote controls.




Video 3 - Up The Garden path

DIY Obstacle Course

 A fun run where OrangeBot fights two monsters ;) The video is from the POV of the operator on the laptop. The robot can be controlled looking just at the stream thanks to the low latency.



 Video 4 - DIY Obstacle Course

Technical and Artistic Merit

An explaination of how OrangeBot operates.

Illustration 4 - OrangeBot Architecture

Illustration 5 - Remote Controls




Video 5 - Technical and Artistic Merit

Conclusions

What I'm happy with:

  • Remote controls: Browser controls, local hosting and reliable with 7ms latency 
  • Turret: Pan, Tilt, 6mm spring loaded gun that shots safe 6mm soft pellets precisely, laser pointer, camera. Practical and fits well with the aesthetic of the robot.
  • Power System: good power delivery, good battery duration, easy swap, excellent H-Bridges
  • Aesthetic: OrangeBot looks great to me.

What I'm okay with:

  •  Video Streaming: 150ms of latency with some bugs. I can do better but is servicable.
  • Software architecture: websockets, browser control and local node.js server work. I can do better and learn ROS and do a ROS based application to run on the raspberry pi
  • Reliability: The robot has served two years and is still working.
  • Electronics: The boards and wiring works, I need to make PCBs once some fundamental issues have been solved

What I'm disappointed about:

  • Robot Precision: Initially i decided to have 20Km/h speed for the lava Palaveer challenge in 2019, trusting that the PIDs would do their magic and achieve precision. Well, magic is not of this world, after huge efforts in making the PID more complex and faster with better encoder i hit the limit of the MCU 8b20MIPS yikes! You can see in the submission how much the arena shakes when the robot moves, the PID is trying REALLY hard, but it just can't... With human controlled PWM it is literally impossible to move, so the PIDs are already doing miracles. A better faster MCU with 32bit 108MIPS with even better and faster PID and adaptive PID algorithm was getting there, but would have required an electronic redesign of the robot, and has not been deployed for this edition of the PiWars.
    I learned that magic requires more MIPS and better algorithms to make the unstable->stable!

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