Curving variance

Lorant
Member
Member
Posts: 62
Joined: February 18th, 2019, 2:18 pm
Division: C
State: FL
Has thanked: 2 times
Been thanked: 0

Re: Curving variance

Post by Lorant » February 18th, 2019, 6:07 pm

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?
I build. A lot.
Boca Raton High School.
Events: Boomi, Gravity Vehicle, Wright Stuff.
Incomplete Userpage

User avatar
PM2017
Member
Member
Posts: 522
Joined: January 20th, 2017, 5:02 pm
Division: Grad
State: CA
Location: Enjoying College! :D
Has thanked: 22 times
Been thanked: 6 times

Re: Curving variance

Post by PM2017 » February 19th, 2019, 8:46 am

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?
West High '19
UC Berkeley '23

Go Bears!

falcon1236912
Member
Member
Posts: 23
Joined: February 21st, 2018, 7:59 am
State: MO
Has thanked: 0
Been thanked: 1 time

Re: Curving variance

Post by falcon1236912 » February 19th, 2019, 9:03 am

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.

User avatar
PM2017
Member
Member
Posts: 522
Joined: January 20th, 2017, 5:02 pm
Division: Grad
State: CA
Location: Enjoying College! :D
Has thanked: 22 times
Been thanked: 6 times

Re: Curving variance

Post by PM2017 » February 19th, 2019, 11:57 am

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.
West High '19
UC Berkeley '23

Go Bears!

4Head
Member
Member
Posts: 237
Joined: November 14th, 2016, 11:29 am
Division: C
Has thanked: 0
Been thanked: 0

Re: Curving variance

Post by 4Head » February 19th, 2019, 12:30 pm

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?
2019 Sounds of Music National Champion

User avatar
PM2017
Member
Member
Posts: 522
Joined: January 20th, 2017, 5:02 pm
Division: Grad
State: CA
Location: Enjoying College! :D
Has thanked: 22 times
Been thanked: 6 times

Re: Curving variance

Post by PM2017 » February 19th, 2019, 1:35 pm

4Head wrote:
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.
West High '19
UC Berkeley '23

Go Bears!

User avatar
windu34
Staff Emeritus
Staff Emeritus
Posts: 1364
Joined: April 19th, 2015, 6:37 pm
Division: Grad
State: FL
Location: Gainesville, Florida
Has thanked: 1 time
Been thanked: 22 times

Re: Curving variance

Post by windu34 » February 19th, 2019, 3:12 pm

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.
Boca Raton Community High School Alumni
Florida Science Olympiad Board of Directors
National Physical Sciences Rules Committee Member
kevin@floridascienceolympiad.org || windu34's Userpage

petal
Member
Member
Posts: 7
Joined: October 27th, 2018, 5:22 pm
Has thanked: 0
Been thanked: 0

Re: Curving variance

Post by petal » February 22nd, 2019, 7:05 pm

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.

User avatar
windu34
Staff Emeritus
Staff Emeritus
Posts: 1364
Joined: April 19th, 2015, 6:37 pm
Division: Grad
State: FL
Location: Gainesville, Florida
Has thanked: 1 time
Been thanked: 22 times

Re: Curving variance

Post by windu34 » February 24th, 2019, 8:37 am

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
Boca Raton Community High School Alumni
Florida Science Olympiad Board of Directors
National Physical Sciences Rules Committee Member
kevin@floridascienceolympiad.org || windu34's Userpage

Lorant
Member
Member
Posts: 62
Joined: February 18th, 2019, 2:18 pm
Division: C
State: FL
Has thanked: 2 times
Been thanked: 0

Re: Curving variance

Post by Lorant » February 24th, 2019, 6:02 pm

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?
I build. A lot.
Boca Raton High School.
Events: Boomi, Gravity Vehicle, Wright Stuff.
Incomplete Userpage

Locked

Return to “Mousetrap Vehicle C”

Who is online

Users browsing this forum: No registered users and 2 guests