So for an assignment, I have to make a drag racer so I chose to make it a 6-wheel drive this will be my first time making a drag racer and It must have only TWO motors and a sensor to detect a white line I just want some ideas and help for this assignment.
I am confused what kind of sensor while you use to detect a white line. Would it be something like this IQ Optical Sensor - VEX Robotics Because I did a bit of reading and it seems at least 3 of these sensor if you would want to build a line following robot
I would guess that the sensor can be used to line up on the start line to get staged, and then the finish line. I could see using it with a LED to show red, then turn green at the start line.
As far as building, weight on the back four wheels. Make the frame long to balance out the weight so it doesn’t flip over.
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yes we are using a optical sensor
I was thinking about it and I guess you could zig zag across the line and the. Just change from zig to zag whenever you detect the line
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ok I will try that thanks for the idea
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So far me and my partner have decide on the sketch
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I mean it would be more expensive but you could also just get 2-3 optical sensors and you can drive in a more straight line
I am kinda confused is this iq or vex or exp. Because if it is vex or vex exp then you could just use a vision sensor and it would be a lot easier to code
You make a great point, since this is posted in VEX IQ General, but the drawing has the brain labeled VEX EXP Brain. There are also parts labeled STEEL.
Maybe the mods can move it to the right area when the get a chance.
And you are correct, the V5/vision sensor would also be a choice.
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so far this is what I have and we are using VEXEXP so far this is the prototype we have yet to add the 3rd wheel
my fellow engineer friend, you must use the gear ratios lightning crashes OOOooOOoOoOoOoo gear ratiooooossss
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Also for the code you should use a PID loop. I would recomend watching this video first as it explain the concept realy well https://www.youtube.com/watch?v=4Y7zG48uHRo. Basically you can install the vex vision utility or if you are using the web interface simply click on the devices tab and select your vision sensor. Next you can configure it too detect the white line based on this tutorial https://kb.vex.com/hc/en-us/articles/360035591672-Adjusting-the-V5-Vision-Sensor-in-VEXcode-V5. Once you have the position of the white line calculate the distance from the center of the screen, call this variable Error or something. The you can impliment a PID by folowing that video or with this pesudocode as a guide
integral = error + previous_integral
turn_force = kp * error + kd * (error - prev_error) + ki * (integral)
Even though the integral term has a tendency to blow up to infinity so I would sugest setting ki to 0. using it. Then all you have to do is set turn force to be the speed of the wheels and tune Kp, Kd, Ki to fine tune the movement of the robot.
Sounds great but image failed to load. 
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Traction with more wheels will be >= traction with less wheels. However, if the traction is == to traction with less wheels, stick to less wheels so that you have less momentum for the two motors to spin.
If you, for a straight line drag race, find that 3 wheels (2 powered on back and one idle wheel on front) offer the same level of traction as 6 wheels (both powered), then go with 3 wheels.
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The wheels you have are not known for their high traction. If you have the VEX foam. ( looks like the mesh shelf liner from the grocery / Home Depot) wrap it around the wheels to give yo more traction.
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If you found some wheels like these it may have better traction on regular floors
But aside from that, looks good
That being said you should watch out for build quality try keeping everything square and adding triangles using standoffs anywhere you can for extra support
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