## Curving variance

Lorant
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### Re: Curving variance

falcon1236912 wrote:
PM2017 wrote:
4Head wrote: The more rigid your car is the more an imperfection in the floor will mess up its steering since it will disturb the entire vehicle rather than the vehicle just flexing to absorb the shock.
So how does one fix this issue?
I believe that the car is shifting slightly when you begin to reverse. You can solve this by slowing the car down when you begin to break.
Would a fan help?
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PM2017
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### Re: Curving variance

falcon1236912 wrote:
PM2017 wrote:
4Head wrote: The more rigid your car is the more an imperfection in the floor will mess up its steering since it will disturb the entire vehicle rather than the vehicle just flexing to absorb the shock.
So how does one fix this issue?
I believe that the car is shifting slightly when you begin to reverse. You can solve this by slowing the car down when you begin to break.
By brake, do you mean reverse, or when you actually brake?
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falcon1236912
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### Re: Curving variance

PM2017 wrote:
falcon1236912 wrote:
PM2017 wrote: So how does one fix this issue?
I believe that the car is shifting slightly when you begin to reverse. You can solve this by slowing the car down when you begin to break.
By brake, do you mean reverse, or when you actually brake?
I meant reverse sorry if I was unclear.

PM2017
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### Re: Curving variance

falcon1236912 wrote:
PM2017 wrote:
falcon1236912 wrote: I believe that the car is shifting slightly when you begin to reverse. You can solve this by slowing the car down when you begin to break.
By brake, do you mean reverse, or when you actually brake?
I meant reverse sorry if I was unclear.
Cool; that's what I thought.

Do you have any ideas on how to do this? I would think that springs might be a good idea.
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### Re: Curving variance

PM2017 wrote:
falcon1236912 wrote:
PM2017 wrote: By brake, do you mean reverse, or when you actually brake?
I meant reverse sorry if I was unclear.
Cool; that's what I thought.

Do you have any ideas on how to do this? I would think that springs might be a good idea.
how would you use springs to reverse?
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PM2017
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### Re: Curving variance

PM2017 wrote:
falcon1236912 wrote: I meant reverse sorry if I was unclear.
Cool; that's what I thought.

Do you have any ideas on how to do this? I would think that springs might be a good idea.
how would you use springs to reverse?
Not to reverse, but to slow the car down around the time of reversal.
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windu34
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### Re: Curving variance

Lorant wrote:We have tested and competed on countless surfaces from linoleum to wooden planks, and our car still consistently draws a flatter arc on the way back, so I don't think it is the floor. My original guess was that the string on the axle would bend the chassis and as it decreases throughout the run, would change the arc. So, I built a car meant to minimize this bending, but the curve variance is still there. What else could be causing it?
This is most likely due to oversteer on the way to the cup target point and then respective understeer on the way back due to differences in velocity (youre probably going faster forward and slower backwards). The best way to account for this is to have independent data for going forwards and backwards that is recorded along with avg velocity. However, if you determine that the velocity and acceleration is about the same every run on both the forward and backwards parts of the runs, you dont need to account for that

I have a vehicle events video posted on the Scioly.org youtube channel that you will find helpful.
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petal
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### Re: Curving variance

windu34 wrote:
Lorant wrote:We have tested and competed on countless surfaces from linoleum to wooden planks, and our car still consistently draws a flatter arc on the way back, so I don't think it is the floor. My original guess was that the string on the axle would bend the chassis and as it decreases throughout the run, would change the arc. So, I built a car meant to minimize this bending, but the curve variance is still there. What else could be causing it?
This is most likely due to oversteer on the way to the cup target point and then respective understeer on the way back due to differences in velocity (youre probably going faster forward and slower backwards). The best way to account for this is to have independent data for going forwards and backwards that is recorded along with avg velocity. However, if you determine that the velocity and acceleration is about the same every run on both the forward and backwards parts of the runs, you dont need to account for that

I have a vehicle events video posted on the Scioly.org youtube channel that you will find helpful.
I'm not sure if you have data/know exact numbers, but as an estimate, approximately how many centimeters in oversteer/understeer is it reasonable to expect from an increase/decrease in run time. For instance, what would be reasonable if I reduce time by three seconds? My car definitely does not travel on the same arc forwards and backwards, but I am not sure how much of this I should attribute to oversteer or understeer from a change in velocity.

windu34
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### Re: Curving variance

petal wrote:
windu34 wrote:
Lorant wrote:We have tested and competed on countless surfaces from linoleum to wooden planks, and our car still consistently draws a flatter arc on the way back, so I don't think it is the floor. My original guess was that the string on the axle would bend the chassis and as it decreases throughout the run, would change the arc. So, I built a car meant to minimize this bending, but the curve variance is still there. What else could be causing it?
This is most likely due to oversteer on the way to the cup target point and then respective understeer on the way back due to differences in velocity (youre probably going faster forward and slower backwards). The best way to account for this is to have independent data for going forwards and backwards that is recorded along with avg velocity. However, if you determine that the velocity and acceleration is about the same every run on both the forward and backwards parts of the runs, you dont need to account for that

I have a vehicle events video posted on the Scioly.org youtube channel that you will find helpful.
I'm not sure if you have data/know exact numbers, but as an estimate, approximately how many centimeters in oversteer/understeer is it reasonable to expect from an increase/decrease in run time. For instance, what would be reasonable if I reduce time by three seconds? My car definitely does not travel on the same arc forwards and backwards, but I am not sure how much of this I should attribute to oversteer or understeer from a change in velocity.
There are too many factors for me to be able to give you a rough estimate. Acceleration and the durometer rating of your treads will play the largest role. It is probably possible to experimwntally-derive a linear equation that could decently predict how much additional variance in your curve that you should expect at different average velocities, but considering that your speed should be pretty constant from run to run, it would probably be easier to just take separate data for the forwards and backwards parts of the curve (measure them independently) and use that in your calculations when aiming
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Lorant
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### Re: Curving variance

windu34 wrote:
Lorant wrote:We have tested and competed on countless surfaces from linoleum to wooden planks, and our car still consistently draws a flatter arc on the way back, so I don't think it is the floor. My original guess was that the string on the axle would bend the chassis and as it decreases throughout the run, would change the arc. So, I built a car meant to minimize this bending, but the curve variance is still there. What else could be causing it?
This is most likely due to oversteer on the way to the cup target point and then respective understeer on the way back due to differences in velocity (youre probably going faster forward and slower backwards). The best way to account for this is to have independent data for going forwards and backwards that is recorded along with avg velocity. However, if you determine that the velocity and acceleration is about the same every run on both the forward and backwards parts of the runs, you dont need to account for that

I have a vehicle events video posted on the Scioly.org youtube channel that you will find helpful.
Could a fan design for the drive arm help with evening out speed and thus making over/under steering more manageable?
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