This is an image of our first design. We initially built a frame that was square. This proved to be too small to handle both the weight and the structure that we wanted to add. Our second frame, which was about the same width but much longer was more stable. It also granted us space to have two mechanisms at the same level without interfering with each other. |
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The Candy Catapult was a combination of two separate mechanisms. It was fairly simple to create the catapult, although it is important to have a stop on both ends. The Candy Conveyor belt was our design from the start. We experimented with different gear combination until we found the effective 1 to 25. It needed to move the candy a slow but predictable pace. We also realized that the candy could fall off of the conveyor belt as the SpiderBot moved around on the floor. |
After experimenting with taping around the entire belt, it was clear that the pieces needed to be flexible around the bends but sturdy at the top (to hold the candy in place). We found that aligning each crevice with its own piece of masking tape provided exactly what we needed. Finally, it was complicated to make this assortment of motors, gears, and lego pieces into a compact piece of machinery. It was important, as the robot needed to be small. This is why the gearing system for the conveyor belt is primarily located on the interior of the design. |
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The SpiderBot was originally designed with four wheels. We allowed the two wheels that were geared seperately to be independent of each other and the other two were connected. This worked well for moving forward and backwards, but it was troublesome when we had the SpiderBot turn. The best solution was to eliminate the two connected wheels and to attach a third wheel. This wheel can rotate 180 degrees, so it does not interfere with the directions from the other wheels. |
We were originally going to have the SpiderBot find humans by utilizing a proximity sensor. We would prevent it from attacking inanimate objects by using reflectance sensors on the bottom in junction with white tape to create a controlled environment. However, the sensors that we had available for our useage could only detect objects within a limited distance. |
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Our solution was to use a combination of a light sensor and proximity sensor. We built a "tunnel" around the light sensor to increase the sensitivity, and this increased its ability to detect and therefore follow the light. You can see our design for the tunnel in the image above. A flashlight was used to attract the SpiderBot's attention, and it would then stop a set distance from the human.
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The spraying mechanism was a more difficult design. We approached this mechanism three different ways before our final design. Our first design was created before we obtained the silly string, so it did not take into account the angle of the spray button on the can. The second design was strong enough- we created a gear train with a lever attached at the end. This turned out to be problematic, as the mechanism could not retract quickly enough, and we ended up with a ball of silly string. |
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Our final spraying mechanism is quickly activated and retracted- therefore, we can get a direct spray of silly string at a good distance.
We used internal gearing at a ratio of 1 to 27 for the final design. It provided plenty of torque to activate the silly string. The flat Lego piece with teeth attached to a stablizing Lego actually hits the button on the silly string.
The punching arm was a simple mechanism with two gears and a motor. We extended the arm further with four additional Lego pieces from our original design, and this did not adversely affect the movement of this mechanism. We also attached a "hand" so that it have a gently touch when it was attacking. |
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