In my previous posts, I analyzed some models used in WRO 2018, 2019 and 2020. In this post, I will analyze several models used in WRO 2017, elementary age group.

The game description, rules and scoring could be found at WRO website: https://wro-association.org/competition/previous-challenges

Model 1

This model uses two touch sensors to control panel-like structures. If the panel touches Jaguar block or Turtle block, it will be pressed back a little bit because the connection pin is not completely fixed. The touch sensor at the back of the panel will be pushed down, giving program signal that one animal block stays at that side. Based on this value, the robot will decide whether to place Scientist block (red block) or Visitor block (blue block) or both.

The two colour sensors are mounted in the front of the vehicle. They are responsible for guiding the robot to identify the black lines on the field.

For this model, the vehicle stores red and blue blocks in two separate vertical tunnels. If you slow down the video playing speed and observe carefully, you will notice that the the lowest section of the tunnel is not encircled by the beams solidly.

The medium motor might connect to a short beam, which is not shown in the video, but we could imagine that when medium motor turns swiftly within a short time, the lowest block will be thrown out of the tunnel horizontally. The other blocks above it will drop down. This is how the unloading structure works.

Model 2

The model uses two big motors to drive wheels. The smart hub is standing at the end of the vehicle.

Its front attachment is unique. It has two touch sensors attached on the top of the frame. When the front-end beams touch Jaguar block or Turtle block, the beam will press down the touch sensor on that side, so the robot could know how many animal blocks exist in that zone.

The video does not show clearly the unloading structure of red and blue blocks for this model. Generally, it uses the similar structure to that of Model 1, but have more advantages. One is that the unloading structure is put close to the center of the vehicle. When the blocks are unloaded, they will not roll too far away or out of the boundary. The other is that a panel covers the exit position. It prevents the blocks from slipping out unexpectedly. Meanwhile, when the block is pushed out, it will not roll over too far. This feature is a good improvement compared to Model 1.

Model 3

The model mounts two colour sensors in a horizontal beam. When the vehicle moves straight towards the Jaguar block or Turtle block, the colour sensors are facing directly toward the blocks. Therefore, they could use colour to judge if the animal block exists in that position. Meanwhile, they are also responsible for pushing the animal blocks into the target area.

Here, the idea is similar to that of Model 1 and Model 2: the vehicle should know how many animal blocks are placed in that area. The previous two models use touch sensor to recognize this value, while this model uses colour sensor to realize the same function.

The two medium motors are mounted vertically to drive unloading structure for red and blue blocks. Same as Model 2, we could not see the inside structure through the video, but the general idea is the same. Installing red and blue blocks in separate vertical tunnels and when medium motor spins, some beam-like structure will push the lowest block out of the tunnel.

Pay Attention to Special Case

WRO competition will always contain some random elements. In WRO 2017 elementary group, the 3 Jaguar blocks and 3 Turtle blocks are randomly placed in 6 areas. Furthermore, there is more than one way to place the Scientist (red block) and Visitor (blue block) blocks.

If possible, always use variables to record the number of placed red and blue blocks, Jaguar and Turtle blocks. If your team is lucky enough, in some conditions, when your vehicle passes through the 3rd, 4th or 5th scanned areas, it might have already placed all the blocks (including 3 Jaguar blocks, 3 Turtle blocks, 4 Scientist blocks and 4 Visitor blocks). Your program should check those variables after leaving each area to decide if it has accomplished the mission and could go back to Finish Area directly. In a competition, the completion time counts a lot. Especially when several teams get the same score, ranking is decided by the shortest time recorded.

That is all for the brief introduction of WRO 2017 elementary group models. Enjoy the design and have fun!

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