We use 4 large motors. Two are the drive motors. One operates the rectangular arm at the rear of the robot. The last one controls the front arm and is also used to drive the gear for the chicken mission.

We use a PID gyro algorithm to ensure accurate straight driving and turns. Each movement has an acceleration and deceleration phase to minimize wheelspin and skidding. There are two colour sensors on our robot but we ended up not using them this year, as there are very few useful lines on the mat. We found that the gyro sufficed and was faster than line following. In previous years, we used the colour sensor to stop at and square to a line, but this year's mat was too colourful and some lines only had a white background on one side. We also square up to mission models at 0.25, 1:10, 1:39 and 1:56 and the wall at 2:10 to reset the robot's orientation after driving longer distances to correct for errors.

@@NitrousGasMan - would you or teammates, or your mentors/coaches be willing to visit with two of our team members from 22251 Children of Apollo and a coach or two to discuss PID control and accel/decel.? We had some skidding issues on Saturday at qualifiers on 'fresh' mats, and would like to learn from another team as we grow. Would that be possible? This is Coach Mike with Apollo, my daughters (12 and 10) are members of the team; their older brothers are part of FTC 5356 TARDIS.

@@MLSimons1 Hi Mike, Our team does a lot of outreach and we would love to meet up with your team. One of the other coaches runs our email and you can contact us at [email protected] to set up a time.

Thank you for your comments. Our robot did not perform as well as hoped in Detroit. Our second run could have scored very well, but the robot accidentally nudged the ball and it wound up jamming inside our 3D printer attachment, sabotaging our entire last mission. The attachment using LEGO pneumatics is used only to lift the Strength Exercise bar. It does not perform the Aerobic Exercise mission.

Agreed, especially compared to what they had at regionals.

Thank you for your interest in our robot. In previous years, there was a junk penalty for leaving behind robot attachments on the playing field, but the INTO ORBIT Challenge Guide describes no such penalty for this year's robot game. During the Space Travel mission, the robot is required to "start each Payload clearly rolling down the Space Travel Ramp". The only requirement is that it must be rolling independently by the first track connection. There is no stipulation that it must be set in motion by lifting the orange part of the track.

@@NitrousGasMan Oh right, I see, I'll look back over that! Thanks for pointing those things out there, that should be helpful! Again, I did really love watching the robot work, a nice contrast to my own!!

Thanks for the tip. The arm is just under 12 inches in height. We won Champion's Award, First Place at our provincial championship, so we will advance to the FIRST Championship in Detroit.

@@NitrousGasMan good luck guys!

There are 2 light sensors, each one in front of a drive wheel. When the robot approaches a line, each light sensor stops its corresponding drive wheel when it senses black. Then it reverses each motor at a lower speed and stops it when the corresponding sensor detects white. It repeats this forward and backward motion at progressively slower speeds until the robot eventually comes to a stop. At this point, the robot should be perpendicular to the black line.

@@NitrousGasMan Could you put a block for that?

The robot has knob wheels (Lego part 32072) on its drive axles next to the rubber drive wheels. These knob wheels mesh with a set of knob wheels on the platform attachment to drive it out of base. The knob wheels support the robot and the rubber drive wheels are not in contact with the attachment. When the attachment leaves base, the direction the knob wheels turn pushes the robot towards the south wall. As the robot cannot move in that direction, the result is the motors drive the wheels on the platform attachment. Once the attachment gets to the east wall, the motors reverse direction. There is nothing preventing the robot from driving north. There is more friction in the drivetrain that moves the platform than the resistance to push down the ramp. The result is the robot drives off the platform rather than moving the platform backwards. The design of this attachment was trial and error, and we were fortunate that there was sufficient friction in the attachment drivetrain so that the robot doesn't move the attachment back to base.

We use LEGO 11957 tires and 88517 wheels.

The best illustration of the benefit of acceleration is the second mission where the robot moves from base to the east wall. Doing this at a slow and constant speed would use more time and we would not be able to complete all three missions. Moving at a high speed without acceleration would cause wheel spin and we would not arrive at the exact same location every time. However, by accelerating up to a high speed and then decelerating to a stop, we achieve very repeatable results while still using the minimal amount of time.

What's wheel spin and how is that caused when moving at a high speed without acceleration

Wheel spin occurs when the wheel turns but the robot moves at a slower speed. This usually occurs when the wheel moves too fast for the level of friction between the tires and the mat. Wheel spin results in inaccuracy because the rotation sensor no longer records the correct distance that the robot has traveled. As well, the robot can move sideways, changing the direction it is facing. To avoid wheel spin, the robot needs to slowly speed up instead of starting immediately at a high speed.

Thank you so much!

- Plan ahead to decide on the motors, wheels, and sensors you want to use. - Keep the drive motors as close together as possible, and as low to the ground as possible. - Always build a solid frame around the robot to support the wheels on both ends, to make installation of attachments easier and for general rigidity. - Make sure there are no large empty spots inside your robot. Sensors are good at filling in gaps between the motors and the frame. - Don’t always settle for your first attempt. You will generally have to re-build small sections of the robot to achieve more rigidity and compactness. - While you are building, plan ahead by making more connection points that could be used to strengthen the robot later on. - Squeeze the robot in all directions every once in a while during the build and continue strengthening any weak points. - If you are using colour sensors, make sure that they have shielding from ambient light (ensure that no outside light from the outer environment comes into the sensor). Ensure that they are more than 3mm from the mat, but less than 1cm. - For easy installation of attachments, never use friction pegs to attach attachments onto your robot so that they are quick and easy to install, and so the pegs don’t get stuck on the robot. - All of your attachments should attach onto your robot in roughly the same way. This could mean making a compartment in your robot for all your attachments to slide into the same way. Your attachments will probably have the same base structure that fits onto the robot. - If you are using A and D motors, there are many ways to make the attachments slide in easily. You can use gears facing up on the motor, and the attachment has gears that mesh with those. Alternatively, use knob wheels on your robot and have the attachment have axle pegs that fit into the knob wheel. There are many other ways, as long as it does not involve putting an axle into a hole.

Hello Ctrl+Z. Thanks sooooooo much for the feedback. Just asking, would it be a good idea to have the motors inverted? Thank you once again

You can orient the drive motors either way, as long as the wheels you use are large enough so that the motor housing does not touch the mat. The only other issue is when you flip the motor, the robot will move in the opposite direction for a given power.

I do not understand what you mean by 2-1 rod. The flower is held upright by the water deposited in its base if that is what you are asking.

NitrousGasMan sorry, I meant the 1-2 half thick beam with two axel holes. It looks like it would rotate freely. Thanks!

AlexAlexievBVG Nice design, thanks!

Hopefully you guys make it to regionals or states or to where ever you guys are going!

We use LEGO 11957 tires and 88517 wheels purchased from a seller in Germany on Bricklink. Thank you for the support. We will be competing in our provincial championship soon.

Thank you so much!! Good luck and you will win! :)

Also, nice idea for tilting the rack in the first mission

You're welcome. We wanted a simple mechanism to flip the manhole covers and stumbled upon this design through experimentation.

I personally like that part the most too!

We created a MyBlock to automatically accelerate and decelerate. We input the starting power and target power for the drive motors. The block starts the robot moving at the starting power and slowly adds a fixed amount to it every time the loop iterates until the target power is reached.

NitrousGasMan thx

We are a school-based team from Toronto, Ontario, Canada.

Did you win at the last year world championship in st. Louis?

Yes, we won Champion's Award at the FIRST Championship in St. Louis last year. We were definitely not expecting it, but the team had a really good Q&A session with the judges during the final callback.

I was there too, on team macgyver. This year i am going to detroit with a team called Septem. Looking forward to meeting you!

We remember team MacGyver from St. Louis. Congratulations to Septem for advancing to Detroit this April and we wish you the best of luck. We are competing in our provincial championship soon and we will see if we are fortunate enough to advance to an international tournament.