Getting ready for PiWars@Home

So, what about all these new challenges then?  The new challenges for PiWars at Home were announced at the start of September 2020. 

As in previous competitions, there are several ways to perform each challenge with differing amounts of points available for each approach.  We will make every effort to gain maximum points for each round so will generally attempt the most challenging method.

Let’s look at each game:

Feed the Fish.

The rules say that the robot can be remote controlled or autonomous, but it is not clear if an autonomous approach yields more points.  However, the game is against the clock and it is possible that an autonomous machine could be quicker: delicate aiming by radio control can be time consuming.  For this reason, we will keep an autonomous design in mind.  To begin with we will try to use PiDrogen’s odometry, inertial measurement and time of flight systems to manoeuvre the robot from the loading to the firing location on the arena.  However, we might also use video guidance if the simpler systems are insufficient.

Since the game is against the clock, we will try to create a design which fires five rounds at once.  The design will also need to be quick to re-load (since we think the re-loading time is part of the game).  Finally, the launching mechanism will be based on a catapult so that projectiles can be lobbed rather than shot with a flat trajectory so that they can drop into the top of the “aquarium”.

Extra “artistic merit” points are available for a nicely decorated aquarium.  Since this is a robotics competition, we’re thinking automaton.  But only if there’s time at the end.

Tidy Up the Toys

Again, we will be seeking the highest scoring approach to the game.  This requires that the robot stacks the boxes using an autonomous control system.

We have a barrel lift mechanism that was built for the Eco-Disaster game in the 2020 games.  This works well for barrels and could easily be adjusted to lift the toy boxes (by changing the jaws).  But it could not lift one barrel and place it on another.  So, a redesign is needed.

The game is against the clock, so we hope to lift the red box, drive to the green, place the red on it, then lift both the red and green box and drive them together to the blue box.  Finally, the robot will lift all three boxes and deliver them; hopefully, this is quicker than delivering the boxes one at a time.

We’re thinking that we might take another look at the motor interface software; it will be useful for this challenge if the robot can be made to make smooth movements, i.e. where acceleration and deceleration rates are controlled.  This will be a nice addition to the robot in any case.

Up the Garden Path

This game is a variation of previous line follow games.  PiDrogen can already use video guidance to follow a line, although it has no code to resolve routes at junctions.  It would be fun to add this functionality, but video guidance is not the highest scoring approach to the game.

Instead we will attempt to provide PiDrogen with a speech recognition system; this being the highest scoring method.

Analysis of the route suggests that we could use a fairly minimal repertoire of commands; we propose to use directions based on the numbers of a clock face.  To follow the route the driver should say “three”, “two”, “three” to get to the start of the first curve.  Then the driver should say “anti” meaning drive around the semi-circular part of the curve.  The full set of words that should be resolved will be: two, three, nine, ten, anti and clock.  The robot can stop at the end of the course based on the front facing time of flight sensor.

We have a pair of Blue Tooth headphones with excellent sound quality.  We hope to be able to connect these to PiDrogen’s Raspberry Pi brain and have it resolve verbal commands since this is explicitly allowed in the rules.  We think this will be more reliable than mounting a microphone on the chassis where ambient noise is likely to be a problem.

PiDrogen is quick at following a line with the camera.  It is even quicker making moves based on odometry and the IMU.  We may have to choose between a fast time recorded using odometry / video guidance or a slower time using voice guidance.

DIY Obstacle Course

At the moment we don’t have much of a plan for the obstacle course.  But there are a couple of thoughts at this time:

  • We think PiDrogen is pretty good at moving over obstacles.  P19 did quite well in the obstacle-based challenges in 2019 and P20 has had many updates that should make it better still, such as improved ground clearance, a smooth underside etc.  We want to demonstrate how well our machine can traverse obstacles, so we need to develop a challenging course.
  • In this game we will not go for the maximum points approach (which is an autonomous machine).  Instead we will use radio control so that our chief driver can demonstrate his skills.

That’s all for now.  Next time we will get into detail about one of the new game implements.

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