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Subject: 
Re: cybermaster
Newsgroups: 
lugnet.robotics
Date: 
Thu, 3 Aug 2000 10:27:50 GMT
Original-From: 
Laurentino Martins <lau@!NoMoreSpam!netcabo.pt>
Viewed: 
918 times
  
At 10:47 03-08-2000 Thursday, you wrote:
Hi! I've read the article you wrote the robotics list!

I also have cybermaster and want to design something similar. My question
is, do you lost everything? DOn't have a description or something else?
It's long time to do it from start! Cybermaster is much better then rcx,
because of communicating with radio.

Do you have a suggest how can i start this project!


Here some advices:

1. Don't try to do everything at the same time right form the start.
Do the basics then add features with time. That way you will not get discouraged by the complexity of the project (and bugs all over the code).

2. Be prepared to tweak NQC code. The CyberMaster memory is small. To create basic instinct movements in it and at the same time respond to the PC orders, you better know how to optimize the size of the code.

3. Know how to use the tachometers. Know how to rotate the bot any angle using only the motors and monitoring the tachometers. It's very precise, but has to be done in the bot side.
As a bonus you should know how to calculate speed and how to detect impacts even without a single touch sensor. It works very well.
It can even detect when the bot tries to climb something too steep.

4. Read about odometry. I can't find the link, but there is a nice PDF in the net that explains everything you need to know about odometry. Is someone knows the link, please post.
The implementation is linear. You have to use the two odometers to know the rotation the bot is describing. You'll have to average the last two or tree reading to have a precise reading due to fluctuations the readings sometimes display.

5. Be prepared to deal with odometry errors and how they accumulate thru time. You can do little to improve the accuracy. The type of the floor influences greatly the accuracy.
You better concentrate your efforts on how to auto-correct the PC routines instead: I mean, if an impact was detected at point X and a previous impact was detected at point Z which is beyond the X, that means that probably the X is the same as Z (or otherwise the obstacle moved).


This was my most rewarding project ever done with the CyberMaster.

Good luck! :-)

......


My current project:

I've mounted a web camera in the CyberMaster. I've bought a 5m cable (USB) and have let it free.
The tracks have lots of traction and can keep up dragging the cable after the bot without (much) influence in the bot direction.
I've managed to capture the camera image in the PC (in M$ Visual C++) and right now I'm working in an image recognition algorithm.
The idea was not to use odometry, but to use the camera image to track landmarks, like a line drawn in the floor, walls, etc.
I'm stuck in the recognition algorithm - out of ideas.


Laurentino Martins

[ mailto:lau@netcabo.pt ]
[ http://www.terravista.pt/Enseada/2808/ ]



Message has 1 Reply:
  Re: cybermaster
 
(...) My original idea was to create a path of while sheets of A4 paper in the floor and make the bot follow the path. The floor is dark, so the white sheets can be easily seen. The main problem is what to do with all the flow of graphics the camera (...) (24 years ago, 3-Aug-00, to lugnet.robotics)

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