Build blog 2020

The robot's birth


This year priorities are efficiency and timeliness. With the removal of the stop build day, we have a much shorter build period than the other teams. We participate in Los Angeles regional in week 2 but we must send the robot 2 weeks before. That’s why we have to build the robot in 5 weeks instead of 8.

Philosophy for efficiency: everyone must be involved. You can’t afford giving important jobs only to a few students. Two rules flow from this: everyone must clearly know their role and we must trust everyone in the team.

To get prepared for the season, we did a “practice kick-off” two weeks before the real kick-off. The steps were well mastered on D-Day:

  • Watch the game reveal video

  • Analysis of the game manual in small groups

  • Prioritization of the objectives (what we want the robot to achieve)


Prioritization of our Infinite Recharge objectives

1: Throw balls in the outer port, then in the inner port

2: Grab power cells on the field

3: Store 5 power cells in the robot at the same time

4: Hang on the shield generator

5: Cross the trench

6: Manipulate the control panel (stage 1 and stage 2)


Construction season organization

Students are divided into 6 groups of 4. Each group consists of at least one student specializing in CAD and one student specializing in programming. An objective is assigned to each group, the priority objectives are reserved for the most competent groups. Each prototype group can use our CNC and 3D printers. We also follow the agile method, which forces us to iterate.

Design of mechanisms

1: Throw balls in the outer port, then in the inner port

This objective follows an iteration process: we try to throw a ball, then throw it into the bottom port, then into the outer port, then into the inner port.


Shooter: We first opted for a flywheel. One advantage is that the balloon flies turning on itself: this makes a more precise trajectory. The axis is powered by two 775 Pro.

Adjustable hood: It is powered by a bag. It can control the shooting angle. when retracted we can shoot against the powerport.

Turret: It is also powered by a bag. Two movable plates rotate on either side of the stationary plate thanks to bearings placed between them. A transmission chain drives the outer plates.

2: Grab power cells on the field

Intake: We prototyped the first intake with two lines of 2” AndyMark maroon compliant wheels driven by a 775 Pro. We had to do many tests to find the right distance to the bumpers.


As no mechanism must protrude from the frame perimeter before the match, we must be able to retract the intake. So we decided to rotate it using actuators.

Unfortunately, the first tests were not conclusive: too much pressure + weak points on the intake arms = epic fail

After a lot of tests on the actuators position and a strengthening of the arms, we succeeded. On the video Juliane helps it a little bit… But we limited its strokepract thereafter and everything went better.






3: Store 5 power cells at the same time in the robot

Conveyor: we prototyped a conveyor with a belt system on the outside and rollers on the inside to guide the power cells.

Prototype 1: The power cells were driven by the belts, but they could not stop when the conveyor was full (they continued to enter and crashed to the bottom).

Prototype 2: The belts were replaced by a large elastic and were moved inside. The rollers were moved outside. But the conveyor was too large and did not allow enough balls to be stored.


We are working on a version 3 which will be simpler: the balls are conveyed to the shooter thanks to a slight slope. It has a triangular shape that lets pass only one ball at a time. A wheel placed on the side brings the balls one by one into the feeder.

Feeder: it grabs the balls laterally and put them up into the turret. The two lines of wheels rotate in different directions, so the balls go up without rotating.

Prototype of the feeder, the turret and the shooter together.




4: hang on the shield generator

To get the hook up, we prototyped a telescopic arm and a scissors lifter. We opted for the arm because it’s more compact. It brings the hook on the bar, then it goes down and the robot goes up thanks to a winch.




Winch: Four ropes are attached to the hook and wrap around the winch. It is powered by two Cims.

Telescopic arm: The telescopic arm goes up thanks to a cascade rope system. We prototyped it with four metal profiles of different widths, but the ropes rubbed against the profiles. Also, when deployed, the arm leaned due to the gaps between the profiles. That’s why we printed 3D pieces to guide the ropes and to fill the spaces between them.

Hook: The hook has two sides to make driving easier: the robot can be positioned on both sides of the scale. The two ends bend when they are placed on the bar. It allows to limit the height of the arm on the robot (and not to exceed 28 inches). It makes easier to place the hook on the bar because the horizontal surface is larger.

Hanging points on the robot: We chose to hang the robot thanks to four attachment points in each corner. It maximizes the stability, which is important not to exceed 12 inches from the frame perimeter.

This is our last version of the entire climber on the robot which is currently being laser cut.


​5: Cross the trench

​Even though we put this objective in 5th position, we think that crossing the trench can make a big difference in match. That’s why we chose to design the robot within the limit of 28 inches.

6: manipulate the control panel (stage 1 and stage 2)

We are late with this project. Prototypes are in progress, but we didn’t have time to test them yet.

All of our mechanisms are now being laser cut and we’re waiting for them. We’ll be happy to hear your thoughts about our work.













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