Tuesday, December 9, 2008

Building coarse robot

Building the robot to do the 4 sensor obstacle course will be very tricky and complicated. We will have to attach a sound, touch, ultrasonic, and light sensor all to one robot. Our robot is going to be jammed pack but it is possible to do.
First the light sensor, it will be easy because you can only put it in one spot. We placed it in the back of the robot facing the ground.
Secondly we attached the touch, you can only put it in the front of the robot to do what its supposed to do so thats what we did. It wasnt that very hard to attach.
Then we placed the sound sensor on the robot. We put the sound sensor on the side of the NXT facing up so that it could here the sound fairly easy and not get in the way of the touch and light sensor.
Lastly we put on the ultrasonic sensor. This was the hardest sensor to put on because we also had to put it in the front, so we put it right about the touch sensor. Another trick we did was made the touch sensor attractable so when it hit the wall it could move behind the ultrasonic sensor so it wouldnt get in the way.

Get in gear

The get in gear investigation was about the driven and driving gears. Both the driven and driving gear do something that can change alot on the robot. If the driving gear was bigger than your driven gear then the robot would travel faster because the rotation of the driving gear once would cause the driven gear to rotate multiple times due to each turn being. For example, 8 teeth and 2 teeth on the other so that each time 8 teeth turned around completly, 2 teeth turned around 4 whole times. Another thing is if the driven gear was bigger than your driving gear then the power in the wheels would be stronger though causing the wheels to be slower and shorter distance traveled if using a rotation sensor because every 4 turns of a 2 teath would cause only one wheel turn if the driven wheel was a 8 tooth gear.

Gears and Speed


In the gears and speed investigation we had to determine which of the two hypotheses given to use were correct, or at least which had a greater percent of accuracy.The correct hypothesis was found by compairing gear ratios and the distance traveled over three seconds of movement with 100% motor power and averaging them to find the average distance traveled, and then dividing by three (the amount of time) to produce the average speed.The hypothesis that ended up being correct was B because it didnt have that much error.

Gears ch. 2

Chapter 2 talks alot about gears. It says how to count teeth to get a gear ratio that you can use to convert speed to power. Gears are used by having little teeth around it that fit in another gears groove to make a spinning movement. The torque and velocity are different things one is the power the other is the velocity of the robot. to get speed you need a gear with many teeth that drives a gear with less teeth to get the torque you need, the opposite with one gear with less teeth and the other gear with many teeth. Changing the gears teeth creates a different ratio that changes the speed of the robot.
A warm gear is a usefull gear because it can only move in one direction so if you are trying to lift a arm then the arm wont fall down. Another wheel is the bevel gear that is used to change direction with between perpendicular axis.The last wheel is the know wheel. That wheel is actually not a wheel it is a four pieces gear that one part that pushes the other parts

Tractor pull

The tractor pull challenge is going to be a fun one. It is not a race of speed, but a race of strength. This is a test of which robot can pull the most weight a distance of 50 cm in the least amount of time. To make your robot able to pull more weight you will need to make your robot a little bit heavier to put some friction on the wheels to keep them from sliding. The gears you would want to put on it are a big driven gear connected to the motor with a smaller driving gear. You might even want to put 2 rows of gears to increase its power.

Thursday, December 4, 2008

Drag Race Challenge

We are entering the final leg of the coarse and as an end challenge we are going to be creating the fastest robot gear ratio known to man kind. In order to make our robot go fast we will have to lighten up our robot and send him for the finish line with the smallest time. I think we have the upper hand coming in to the challenge because we are so exited! The coarse is going to be a length of 3 meters, and i dont think that raw speed will win, but whoever has the fastest acceleration will win because the coarse is so small.

Wednesday, November 26, 2008

Building Strategies ch. 6

The whole idea of Chapter 6 is about Supports. Mostly every robot built or car built is in need of supports. Having Gears is one of the most important parts of supports, a gear that is placed next to a supporting beam holds the beam well and decreases the slipping of the attached parts to the gear. The best way to resist both Tension and Compression is by adding extra connectors, by adding the connectors, the Tension and the Compression would have been lessened dramatically and with the Rigid assemably, it would not easily fall apart. The way that the new idea of studless beam works is that the studless beams can add both beams with stud and without. The old one only allows stud beams to connect. A creative reason for the studless beams was to let it cover up all the parts that show out. In any case, the most important part is the NXT itself, it is needed to be placed at the center just as a shape of a triangle. The reason for placing it at the middle is because it needs to keep the front and back both balanced, if either side is imbalanced, the robot would fall back or drop forth if it moves. Mainly, all problems lead to weight balance, the NXT itself has quite a big weight, as much as 2-3 Motors, if those both were placed in the middle, both front and back would be fine, but if they were all placed at back, they would tilt. The best ideal way would to be placing the NXT at the back/front, and the Motors at the opposite like a scale balance.