Mindstorms Program Discrepancy

[Gaidzahg]

Hi, I'm hoping someone here can help me solve this riddle.

Going through the Robot Educator tutorials, I've programmed my Driving Base robot to do a full circle turn.  I have duplicated the program exactly as seen in the tutorial, but my robot does not go full circle.  I've tried it with multiple different bases and multiple computers and the glitch (if it is one) is always there.  The firmware was updated on every  base I tried it on.  Every computer I tried it on was running Mac OSX El Capitan.

I made a little video to more clearly explain the problem.  I hope someone here can help me clear this up.

Thanks!

[Kelkschiz]

I may be missing something but I'll give it a shot. I played around with Mindstorms a couple months back, so I am no expert by any measure. Also I didn't follow the tutorial course. First off i'd like to know, is your goal to understand why the robot is not making a full 360 degrees turn, or is it just to make your robot do a 360 turn? The answer to the second question seems to me to simply increase the number degrees the servos turns untill the robot does a full 360. That is generally how I program: program, observe the results and adjust untill it's perfect. 

I am afraid I can't answer the first, more difficult question. To answer that I would probably have to build and program the robot myself, study/compare the results. Which unfortunately I do not have time for at the moment. 

 

Edited April 14, 2017 by Kelkschiz

[teflon]

I also have limited experiences with tutorial. I am not sure if there are exact numbers or some random ones that you should punch in. However, if you want to be sure if your encoders within the motors function okay, perhaps you could run them for 360°. If the motor (not the robot) does the full circle, than the motors are ok. In that case there could be differences in wheel size, gearing (if there is one) or you have to figure out the number yourself.

I hope this helps.

[Gaidzahg]

3 hours ago, Kelkschiz said:

I may be missing something but I'll give it a shot. I played around with Mindstorms a couple months back, so I am no expert by any measure. Also I didn't follow the tutorial course. First off i'd like to know, is your goal to understand why the robot is not making a full 360 degrees turn, or is it just to make your robot do a 360 turn? The answer to the second question seems to me to simply increase the number degrees the servos turns untill the robot does a full 360. That is generally how I program: program, observe the results and adjust untill it's perfect. 

I am afraid I can't answer the first, more difficult question. To answer that I would probably have to build and program the robot myself, study/compare the results. Which unfortunately I do not have time for at the moment. 

 

Unfortunately, it is the first question I want the answer to.  Why does similar programming result in different results?

I'm beginning to think that Lego did not attempt to match the programming to the video after all.  

[aeh5040]

I'm not sure if this is what you are asking, but the angle turned will depend on four things:

1. number of rotations performed by the motor

2. gear ratio, if any

3. wheel diameter

4. distance between wheels

Only 1. is under the control of the program.  And if it is done by timing rather than via the rotation sensors then even that will also depend on load and battery condition.

[DrJB]

52 minutes ago, aeh5040 said:

I'm not sure if this is what you are asking, but the angle turned will depend on four things:

1. number of rotations performed by the motor

2. gear ratio, if any

3. wheel diameter

4. distance between wheels

Only 1. is under the control of the program.  And if it is done by timing rather than via the rotation sensors then even that will also depend on load and battery condition.

You need to make sure two keypoints are absolutely correct.

1. That the program is correct

2. That the physical build is exactly the same. If you've used any gears or different tires/wheels, that might explain the difference.

[mocbuild101]

It could be the batteries, but you could also try making the program slightly different: (motors on) (wait for degrees) (motors off -brake).

that would rule out the slightly flat batteries.

[Gaidzahg]

3 hours ago, DrJB said:

You need to make sure two keypoints are absolutely correct.

1. That the program is correct

2. That the physical build is exactly the same. If you've used any gears or different tires/wheels, that might explain the difference.

Both are absolutely correct.

2 hours ago, mocbuild101 said:

It could be the batteries, but you could also try making the program slightly different: (motors on) (wait for degrees) (motors off -brake).

that would rule out the slightly flat batteries.

That is a good point, and I retried it at various levels of charge from full down to nearly empty (it's a rechargeable battery).

4 hours ago, aeh5040 said:

I'm not sure if this is what you are asking, but the angle turned will depend on four things:

1. number of rotations performed by the motor

2. gear ratio, if any

3. wheel diameter

4. distance between wheels

Only 1. is under the control of the program.  And if it is done by timing rather than via the rotation sensors then even that will also depend on load and battery condition.

Everything you said is true, but all four conditions are exactly the same between the model in the video and the model I used. 

8 hours ago, teflon said:

I also have limited experiences with tutorial. I am not sure if there are exact numbers or some random ones that you should punch in. However, if you want to be sure if your encoders within the motors function okay, perhaps you could run them for 360°. If the motor (not the robot) does the full circle, than the motors are ok. In that case there could be differences in wheel size, gearing (if there is one) or you have to figure out the number yourself.

I hope this helps.

Thank you.  I did test the motors by doing just that.  Each will correctly turn whatever number of rotations I program, so I know it's not them.

[mocbuild101]

This is getting very confusing!

Try copying all of the program, but using keyboard shortcuts.

Like this: select all the blocks in program 1 (the one that works) and press Ctrl+C, then go into program 2 and press Ctrl+V, then just run it as normal.

If that doesn't work then just make the degrees that the motors rotate bigger.

Edited April 15, 2017 by mocbuild101