Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: gfscustoms on January 02, 2009, 10:38:10 PM
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Hello,
I have been reading these forums for a long time now but have not posted a ton.
I building a small quadruped robot and I have run into a problem with signal processing.
I need to be able to run:
4 IR distance Sensors
2 ultrasonic (Ping) Sensors
4 Force Resistance Sensors (foot sensors)
The processor that I am using to drive the servos and control does not have the ability to run the Ping sensors.
So I figures since I will need a separare processor for the Ping sensors, I might as well run all of the sensors on a dedicated board, and then just have my main microprocessor handle everything else.
That being said, I am trying to figure out what microcontroller would be best for me.
this board will soley handle these 10 sensors, so I do not need too much.
I have looked into the Axon, the Roboduino, Bot-board II ect...
Is there an option out there that is better for this task? Of course I would like to spend as little as possible in order to buy other components, and not get something that is overkill. The main board has an Arm9 processor, so it is more than capable of everything else.
Thanks for any input you may have, let me know if more information would be helpfull.
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Hi,
Just multiplex the sensor inputs and the ARM should be able to handle them all.
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An ARM is more than powerful for that...
Don't expect someone will get you the code you want....
Just plug an sensor and you are ready to go...
If you want something else be more specific...
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Thanks for the replies, I'm still pretty new to microprocessors, but the problem that I have is this:
From what I have read/been told, the microcontroller that I have cannot easily work with the Ping sensor. It has analog Inputs, and the problem is that it does not have the ability to send the inital pulse to the Ping sensor, it can only receive.
This problem can be solved by a lot of work with the FPGA but honestly this is way over my head, and with all of the work I already need to do to get this all working, I thought a second microcontroller would be easier to handle the sensors.
I am not looking for code, just if anyone has a suggestion for a simple microcontroller that can handle these sensors economically.
thanks
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What are you trying to build... From what I understand you have a DSP in your hands...
quite useless in you want to build a robot...
I noticed it has 8 UARTs so talking to the outside world won't be difficult...
Typically, a AVR will do... And there are programmers than can be build for less than few dollars...
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Here is what I have:
"A quick overview of Qwerk’s hardware features:
· 200 MHz ARM9 RISC processor with MMU and hardware floating point unit
· 32 Mbytes SDRAM, 8 Mbytes flash memory
· 4 closed-loop 2.0 Amp motor controllers (supports quadrature encoder and back-EMF “sensorless” position feedback as well as
current sensing)
· 16 RC-servo controllers
· 16 programmable digital I/Os
· 8 12-bit analog inputs
· 2 RS-232 ports
· I2C ports
· 2 USB 2.0 host ports for connecting standard USB PC peripherals
· 10/100BT Ethernet port
· Built-in audio amplifier with MP3, PCM and WAV audio support
· 4 Amp switching power supply, 90% efficient, 7 to 30 Volt input range
· Rugged aluminum enclosure
· 5.1” x 5.8” x 1.3”, 12.8 ounces"
as I said, the analog inputs are strictly input, so they cannot send the Ping the initial pulse.
I may be able to do a workaround, but I thought I would just offload all the sensor processing to a separate microprocessor, since making this board do it is above my current experience.
Here is an image of the bot.
(http://img.photobucket.com/albums/v146/gscustoms/bot1.jpg)
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First of all, nice looking bot you have there! ;)
One thing I don't get though, how will it be able to walk? I don't see how it will lift its legs?
Anyway, why don't you just use a free output pin of the ARM processor to give the initial pulse?
Just connect it to the PING using a diode...
It seems like a waste not to use all those beautifull IO specs of your processor...
Howmuch did that thing cost btw? can you give me a link?
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Maybe that is the best idea. I will have to do a bit of research on doing that.
Here is a link to the Qwerk processor: http://www.charmedlabs.com/index.php?option=com_content&task=view&id=29
Unfortunately, they have discontinued sales directly. Eventually they will be licensed to VEX and distributed through them.
I paid like $300 or $400 a couple years ago. It's been sitting on the shelf ever since, I finally have a bot to use it in!
The body pivots in the middle, here is another picture: (http://img.photobucket.com/albums/v146/gscustoms/bot2.jpg)
Basically it has a capability close to a 3DOF per leg quad, but uses the center pivot instead. I can't take full credit for the idea, aprofessor named Kan Yoneda originally created a few bots using this type of setup, allthough his were large bots.
Also, the image is a bit out of date. I now will be using gears to connect the servo to the legs in order to get more travel out of them.
I should be getting my pieces from the laser cutter on monday and will finally have everything I need to begin building. I will take pictures as I build, hopefully everything will work out. I've spent the better part of a year working on this!
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okay,
keep us posted! ;)