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21
Electronics / Motor control...New at this...
« Last post by TRIAL_and_TERROR on September 23, 2014, 09:53:45 AM »
So the noob that I am I have found myself buried in books and searching online schematics to no avail.  Essentially I have two 24vdc motors from a wheel chair that I need to come up with some sort of controller for.  I tested the motors and they peak free load at about 40A and confirmed that the manufacturer had a 60A controller on board.  I would like to create my own H-bridge (reversible dual channel) to help save cost as well as ease of replacing parts. 

I wanted to just use relays, but heard that MOSFETS can be incorporated to create the effect of speed control?  I am way to knew at electronics and am having trouble finding a parts list or schematic that also spells everything out.

What I would like to accomplish is an 80A peak dual channel reversible hbridge that would allow speed control without having to spend $200.00 on a commercial one.

Does anyone out there have any insight on how to accomplish this and/opr what components to use?  Also suggestions on circuit protection...oh and everything I have read about always leads to programming...can this be done without having to program???
22
Misc / Professional Wireless Follow Focus System
« Last post by cain82 on September 23, 2014, 06:12:17 AM »
Hi all,

I'm a professional film maker/Steadicam Operator. I'm looking into the possibility of creating a wireless follow focus system for Steadicam. I will test/use the machine in a professional environment as part of the development process and pay for all materials needed.
If you look into the market you will see that the cost of buying one of these can be well beyond the reach of many individuals and even small production companies. I want to develop something for my own personal use, with a view to possibly entering the market if all goes well.
Please note: I know very little about electronics/mechanics, I am looking for a person/persons who will happily create this independently and only look to me for feedback on practical application/testing and finance. I am not looking for a person to do all the hard work who I'll leave high and dry once I have what I need, this will be a joint/equal venture that I hope will benefit both parties regardless of the final outcome (whether or not it works as required.....whether or not it is a viable product for entering the market). 

On the market you can buy this:

Entry:
http://cvp.com/index.php?t=product/redrock_micro_8-114-0007&gclid=CMfVydGj98ACFSXKtAodyiIA2A

to this:

Industry standard
http://prestoncinema.com/index.html

Can we make something with the same standard of quality, features and performance of the industry standard for the roughly the price of the entry level product??

Many kind regards

Neil Cain
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24
Software / McUber Update?
« Last post by kl22 on September 17, 2014, 08:43:55 PM »
Hi Everyone,

If you want McUber to be updated, please go to http://www.yetacorp.com/products/mcuber/ and fill out the survey.

We are conducting a survey to see if there is a high enough demand for a new version and if there is, what the requirements are for it.

Thanks in advance!
25
Software / Re: Problems uploading to Axon II using McUber
« Last post by kl22 on September 17, 2014, 08:16:35 PM »
Hey Hero I,

Just been super busy with alot of other stuff with my company for a while, but still I didn't receive an email from you.

Were you able to get it working? Have you tried what Webbot mentioned? Also, along with the Admin's questions, are you getting any activity from either the board or any progress updates in McUber?

As you can see the project was tabled for a while, but if there is a high enough demand for an application like McUber which was meant to be:
- Cross platform
- Expandable to not only Axon but to other board (by the community writing communication scripts outside of the core application)
- House a customized terminal
+ other requested feature (can be found in other posts in this forum)

I can look into allocating some resources to get a new version out. Admin please advice?

Other than that the only recommendation I could give you is to try out the older programmer in an XP environment to ensure that your board is functioning correctly.
26
Robot Videos / Re: The making of Ant Intelligent Robot
« Last post by ndan on September 17, 2014, 05:50:19 PM »
Also, the compensation refers to a Bayesian  model (probabilistic model) that is integrated within the control loop to improve the accuracy of the odometry (x,y,teta). This in turn gives no measurable impact for the robot turning.

Oh yes, the odometry is computed every 1 ms but communicated to the the main board every 10 ms, not to confuse this with the first post.
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Robot Videos / Re: The making of Ant Intelligent Robot
« Last post by ndan on September 17, 2014, 05:40:40 PM »
Hi,

Yes, the robot has an odometry compensated controller which is updated every millisecond. The odometry in turn is computed for the COG (center of gravity) of the robot taking into account the geometric axis of each motor. I've also implemented functions to get the odmetry (x,y,teta) for any point on the robot edges (including sensor offsets).

I'll post a link to paper when it is published for the actual algorithm.

Also I forgot to mention that all this is not done on the main processor... it is a distributed architecture assuring fault tolerance:
- the motor board has its own controller and does all the computing for controlling the motors and odometry (here is the compensated control algorithm implemented ):
- sensor board has its own controller and does all the measuring and filtering for range and proximity sensors
- camera also... images are presented in jpeg format to the main board
- audio recognition module too ... sends acknowledgements to a previously user trained sound if it "hears" it.
- main board - ganders all data form the modules and it is where the user writes his programs

hope I have answered your question,
Dan.




 
28
Robot Videos / Re: The making of Ant Intelligent Robot
« Last post by bdeuell on September 17, 2014, 02:43:35 PM »
Looks like a nice little robot. Great craftsmanship too.

Having the axis of the motors not aligned seems interesting to me. Obviously it allows for the compact envelope but I think it would add a lot of complexity to your dynamics. Did you implement any special controller to account for this? Have you seen any challenges in the accuracy when turning the robot?
29
Robot Videos / The making of Ant Intelligent Robot
« Last post by ndan on September 17, 2014, 10:26:08 AM »
Hello,


As part of my research project I'm designing a small differential drive robot platform (10x10 cm) with many cool features like:
- speed&position compensated control
- video camera (VGA)
- audio recognition system
- 2 x range sensors (ultrasonic), 8 x proximity sensors (IR)
- real-time odometry feedback (every 10 ms)
- Ethernet Wi-fi, USB
- Programming in languages like: C/C++, Java, Python, Ruby... can be programmed even in bash
- Integrated development environment with real-time debugging over a Wi-fi connection based on eclipse
and much more...


So I thought it would be cool to make a video for the making of this platform... without further ado here is the video. Enjoy  ;D

https://www.youtube.com/watch?v=AZspMbp2PyE

Feel free to post any questions you have.

Chears,
Dan.
30
Yes, it becomes a geared DC motor and you can use the RMF calculator.
R-Pi and the servo driver board will work.

Just be aware that the R-Pi runs a time-sliced OS and is not great for precision timing.
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