How We Created Our Obstacle Course:

Building

The Lasers

Once the building and coding process is complete, this laser setup will calculate the speed of someone running through an obstacle course.


The lasers we are using are the 5mm LEDs Infrared (IR) Break Beam Sensors from Adafruit.

"Infrared (IR) break-beam sensors are a simple way to detect motion. They work by having an emitter side that sends out a beam of human-invisible IR light, then a receiver across the way which is sensitive to that same light. When something passes between the two, and its not transparent to IR, then the 'beam is broken' and the receiver will let you know. " (Lady Ada of Adafruit).

For more information on the IR break beam sensors, click here.


These laser sensors came with the red, black, and yellow wires pictured to the left. They were initially connected to a breadboard circuit board for early testing with the code we wrote.

The lasers were attached to popsicle sticks via rubber band, and the popsicle sticks were stuck in playdough.

Because each set of lasers needs to be on both ends of the ladder, we needed longer wires.

We connected the short, thin wires to the longer, thicker ones to extend the the length of the wires.

The lasers were tested again to ensure a proper connection, and the tests were successful.

The wires are attached to a breadboard. The breadboard pictured to the top left was a standard breadboard that allowed us to attach the wires in a circuit. This was temporary as we needed something that would hold the wires in place more steadily.


The breadboard pictured to the top right and bottom is a solderable breadboard. This breadboard is made to make soldering the wires easier and of higher quality. Soldering the wires to a breadboard provides more stability, and gives a sense of organization. Research was done to ensure that the right wires were soldered together. With this step complete, we are one stop closer to a more finalized product.

The next step in the processes was to test the lasers with the ladder set up. We laid the ladder out and placed 2 corresponding lasers at the 2nd rung and placed the other 2 at the second to last rung. We walked through the ladder to test it, and we were able to confirm that the lasers and the code work in practice to calculate the participants speed. We did realize it may be beneficial to create a more stable stand and to consider attaching paired lasers together so that the lasers interact with each other properly.

The last step in the process was to create a more stable stand for the lasers and establish a good way to manage the wires so that they do not interfere with running through the ladder.

The Force Plate

The force plate is comprised of the following parts:

  • Four 50kg sensors: Each sensor is wired together in a series and attached to a HX711 sensor. This HX711 sensor is needed to detect more precise values.

  • A 12”x12” wooden board.

  • Four 3D printed parts: The four sensors are held in place by 3D printed parts we designed which allow for easy fastening to the wooden board.

The next step in this process is determining the best way to fasten the sensors to the board.


(The picture to the left was taken during the soldering process.)

The force plate was calibrated using weights.

This allows for us to test the force plate's readings for accuracy.

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The above videos were taken while testing the force plate and it's associated code. The code was working: however, the numbers that were outputted were not accurate, so further calibration and testing is to be conducted.

Coding

The Lasers

The coding process began with the Arduino source code. The source code helped us set up the lasers. Further research was done on the Arduino to obtain a better understanding of it as we had no prior experience. The second set of lasers were wired by mirroring what was done with the first set on the breadboard. The code was copied from the first lasers, then pasted and modified so it would be associated with the second set of lasers.

Code was then written so that when the beam from the first pair of lasers at the start of the ladder course is broken, it records the time. When the second pair of lasers is broken at the end of the ladder course, it records this time as well. The difference between the end time and the start time is the amount of time it took to complete the course. There will be a set distance between one set of lasers and the other set. So the code takes the set distance and divides this by the total time it took to finish the course, and this gives the participant’s speed.

The Force Plate

The coding process started with researching ways people have used the HX711 sensor that is in the force plates. It was found that is very common for people to create their own weight scale with the sensor, thus there was public code for the sensors. This code was used as a template and altered so that it would output in newtons as opposed to pounds.