Pay results fee

Sorry, you have not enough credits to pay results fee.

# Calculate the position of an object during travel

Launcher Simonwait
Status Closed Closed 1 year, 9 months ago
Bounty Reward
40

### Labels

physics, mathematics, applied physics

### Description

I am trying to track an object every second. I know the start position in mm and the end position in mm (both could be a positive or negative figure. I know the target speed (mm/s) and the acceleration and deceleration (mm/s^2) which could be different values.

What I am trying to calculate is the position of the object each second. I was originally coming at this by trying to calculate the distance travelled and then either adding or subtracting depending on the direction but my calculations seemed really wrong. Also I need to account for the possibility that the accel and/or decel may be so slow that the object never actually reaches full speed.

• Jun 11, 2013

Hi,

I can help you do what you want, it seems like a pretty standard physics calculation. I would need to know what if the object Is either accelerating or decelerating for the whole time Interval, or if there is a period of coasting in the middle.

Once I've got the job, I'm sure I Can get the results back to you very quickly.

• Simonwait said:

Hi fwizbang

Im not sure if Ive done this correctly as this is the 1st question Ive asked on here. Basically each second will be in a different phase. For instance it maybe (depending on Acceleration and max speed) that the first 3 or 4 secs are in an acceleration, second 5 is just maxing out to the top speed, then 4 seconds of constant speed before decelerating for 3 seconds (again depending on the deceleration and max speed). I suppose this is all governed by the total distance of the entire move.

Cheers

• fwizbang said:

Hi Simon,

Thanks for giving me the opportunity to help you out. I've never had a Zomb proceed this far either, so, at least on this site, I'm a new comer as well.

The best thing to do at this point may be to make sure that we're both clear on the
problem that you want solved, so that there isn't confusion later on. Of course the more information you can give me about the object and its motion, the better predictions we will be able to generate.

Here's what I have so far:

1) The object begins at a starting position(call it x0) and moves in one dimension
(along a straight line) until it reaches a final position(call it xf) some time later(call it tf). We want to predict its position(x) at times(t) in between the start and the finish.

2) Overall, there are three main phases of the motion. An accelerating phase, in which the object speeds up, a decelerating phase, in which it slows down, and possibly a phase in which it moves with constant speed(call it vmax).

If that's not a correct summary, please let me know.

There are also a few things that I need to be clear on so I can proceed:

a) Is the object at rest at the beginning of the motion? Is it at rest at the end of the motion?

b) Are there specific numerical values for the acceleration/deceleration, the starting and final positions, the top speed, and the time the object is moving?

c) What form are you looking for the answer in? In the absence of numbers(see b),
I can give you formulas you can use to generate specific numbers, or possibly an excel spreadsheet you can plug numbers into. Or, if you can provide me with the input numbers, I can generate numerical answers for you.

d) Is there an easier way for us to communicate? (an email address perhaps)
Since you closed the Zomb, it appears that I can't message you directly through
Zombal. ( For future reference, I think it also means that you've already paid me.)
It's going to be hard to send the final results through a comment box....

I look forward to hearing from you.

• Simonwait said:

Hi fwizbang,

Thanks for the reply. Yeah I got the feeling I had slightly screwed everything up when I accepted the answer and it closed everything. I wasnt entirely convinced you could contact me at all!

So the outline is that this is actually a part of some Visual Basic code which gets data from a database and simulates the movement of an object. The database is actually connected also to a system which will move the object in real life through inverters and winches. This is essentially an offline playback.

I terms of the math that I need from you I will try to answer your questions as follows:-

1)
This is exactly right. My code essentially has a timer which fires at 30fps (I said every second so as not to complicate things (I will adapt the end result for the faster framerate). It then updates a graphic showing the position of the object.

2)
Yes there is always an accel and a decel. If there is time within the move there is also a constant speed section.

a)
Typically yes. There could be instances where the object is already moving at the start or is told to change speed in the next move rather than come to a halt. Maybe it is easier for now to assume it starts and ends at rest though? Is it wise to assume this or do we have to start from scratch if this was implemented later?

b)
The database holds data for acceleration, speed, deceleration and the duration of the move as originally calculated by the larger real life system,

c)
A formula would probably be best which I can then add into the VB and it can calculate on the fly

d)
Sorry to complicate this! Ive just had to cut down my post too as it turns out there is a 3000 word limit! Yeah If you email simonwait@gmail.com that might be easier. Sorry

Thanks for this

Simon

• fwizbang said:

Hi Simon,

Thanks for giving me the opportunity to help you out. I've never had a Zomb proceed this far either, so, at least on this site, I'm a new comer as well.

The best thing to do at this point may be to make sure that we're both clear on the
problem that you want solved, so that there isn't confusion later on. Of course the more information you can give me about the object and its motion, the better predictions we will be able to generate.

Here's what I have so far:

1) The object begins at a starting position(call it x0) and moves in one dimension
(along a straight line) until it reaches a final position(call it xf) some time later(call it tf). We want to predict its position(x) at times(t) in between the start and the finish.

2) Overall, there are three main phases of the motion. An accelerating phase, in which the object speeds up, a decelerating phase, in which it slows down, and possibly a phase in which it moves with constant speed(call it vmax).

If that's not a correct summary, please let me know.

There are also a few things that I need to be clear on so I can proceed:

a) Is the object at rest at the beginning of the motion? Is it at rest at the end of the motion?

b) Are there specific numerical values for the acceleration/deceleration, the starting and final positions, the top speed, and the time the object is moving?

c) What form are you looking for the answer in? In the absence of numbers(see b),
I can give you formulas you can use to generate specific numbers, or possibly an excel spreadsheet you can plug numbers into. Or, if you can provide me with the input numbers, I can generate numerical answers for you.

d) Is there an easier way for us to communicate? (an email address perhaps)
Since you closed the Zomb, it appears that I can't message you directly through
Zombal. ( For future reference, I think it also means that you've already paid me.)
It's going to be hard to send the final results through a comment box....

I look forward to hearing from you.

• Simonwait said:

Hi fwizbang. Just checking in that you got my previous message?

Tips

Keep your profile up to date. The launcher will look at your qualifications, experience and feedback.