first robot

I just started my first adventure in designing and building a robot.
In the first step I want to build a four wheel machine based on OOBOT40
controller
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and Futaba S148 Servos.
After that I will add sensors, etc.
I have million questions.
- OOBOT40 was selected as OOPIC software let program easy and quickly
is there better alternative?
- Also selected OOBOT40 instead of OOBOT40-II as former has 4 full H-bridges
(1Amp) and 3 High-Current (5Amp) Drivers.
I think to use more powerful motors in the future with same controller.
To tell the truth I do not really understand if that power would be
enough or not to say for using it with next robot that would carry several
sensors, wireless card, video camera and some other stuff.
- Selection of Futaba S148 Servos was done just because they are popular.
Same, I do not feel/know how powerful they are
Please comment on this simple design.
Thanks,
Ek
Reply to
Ek
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I love my oopic-r It has most the interfacing electronics all ready.. serial comm, standard servo connectors. Its pretty easy to program, as the development tool has some good features. It has this "virtual" circuit concept (which you never have to use BTW) that makes it very flexible. The chip it self has an operating system and interpreter, hence your code is plain English.. Good support groups, online docs get dodgy sometimes...
I have no experience with any other micro...
Looking at the
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page, this looks good too. It has even more circuitry than the OOPic-R The EMI filters would be good to have. I cant tell if this has EVERY thing you need to connect to a DC motor? It looks like it comes complete with four hbridges ( lower power, 1Amp max), but with traces to allow for higher load options.
The oopic-r doesn't have any hbridge circuitry.
That's my $.02.
Thanks
Reply to
danscott
Since the OOBOT40 [with the oopic chip] is my board, I guess I can comment. The advantages are it mounts a DIP-package controller, which can be replaced, and also has a lot of protection built-in on the I/O pins, so it's harder to blow up than boards with all the pins tied straight to the headers. The 4 h-bridge channels can handle 1 Amp current each, which is plenty for a small bot. Motors connect right to the headers, and the oopic objects control the h-bridges. The OOBOT40-II is more like the oopic-r in having no h-bridges, and it interfaces more servos than the OOBOT40. Also, if one day you want to write your own PIC code, you can plug in many of the regular PICs, like 16F877/etc.
- dan michaels
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Reply to
dan michaels
Thanks you both for comments.
I would like to ask more questions if you don't mind.
1. Looking at OOBOT40 description it is not clear for me how big program I can write (how many average lines of [interpreted?] code or whatever) and how much memory I can allocate for data.
2. Second question isn't about OOBOT40, but I want to be sure that I selected a right board. That's why second question is here. I looked at Linux based small controllers. Did not find any/many.
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looks interesting, but it is more PC than controller (I am not pro in electronics though). So gumstix would need a controller for servo/motor drivers? Could you speculate what would robot kit consist of when using gumstix?
Thanks Ek.
Reply to
Ek
The oopic chip has similar data memory limitations but not as severe as the B.Stamp, although the code space is much larger. If you write your own PIC code, using one of the larger PIC chips, you can get lots more data RAM. From the looks of it, the gumstix is a really nice small computer, but it's more a general computer and not the same category as microcontrollers. Similar to running a robot off of a PC. You'd have to interface and program all of the external robotic peripherals. There is a question how well the linux OS would handle the host of real-time tasks required of a robot. Most small robots use some form of microcontroller, rather than a PC.
- dan michaels
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Reply to
dan michaels
I now have a Gumstix waysmall computer. You can think of it as either an embedded board or a small Linux box. The power usage is small. The board itself has a decent amount of I/O.
It should be possible to control a robot fairly directly with a Gumstix computer. -- D. Jay Newman
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Reply to
D. Jay Newman
On the contrary, I think one of the Gumstix biggest weaknesses is not enough practical IO. No I2C. No general IO pads (unless you buy their expansion board, and then that only gives you 20). Bluetooth and USB are nice, but their useless for interfacing with motor controllers, ADCs, or other embedded devices. Yet despite this bottleneck, the Gumstix is still a pretty good platform (decent CPU speed, low price, small size, memory card slot, open source tools). Just don't expect it to solve all your problems.
Reply to
Chris S.
Dan,
could you answer my first question about code and date space for application? This is really important for me as I would like to pickup something that can live longer than on one project.
Ek
Reply to
Ek
I really like Gumstix especially because I have not found anything close, did you?
On the other side the board as a product is very new and can have several troubles compared with already mature ones. Visit to Gumstix.com's forum cleared up more things for me... Board is great, but people want to have a little bit more on it in addition to helping in using of Bluetooth, USB, etc.
Does it make sense to use a pair of boards Gumstix+oopic(other microcontroller)? Is anybody doing it?
Thanks. Ek.
Reply to
Ek
There's a huge range of small single-board computers. Check Google. Linux Devices has an interesting review (albeit somewhat old) at
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PC-104 spec is also extremely popular.
Reply to
Chris S.
How well do these little linux controllers support the kind of real-time programming you need in a robot?
- dan michaels
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Reply to
dan michaels
ipherals. There is a question how well the linux OS would handle
I did, kind of. The oopic allows you to write rather large programs, you can plug in a 32KB eeprom, but the RAM space is rather limited, 85 bytes or so - which is lots bigger than the Stamps. OTOH, it allows you an easy and cheap path into robotics programming, and you can go to something whcih supports larger programming models later. There is so much involved in getting bots to work - mechanical, motors, software, hardware, peripherals, electronics, sensors, state machines, etc - that I think you want to think of it as steps along a learning curve. Hard to know exactly where you want to go at the beginning.
- dan michaels ====================
Reply to
dan michaels
That depends on what kind of OS and software you install on them. So, as long as you use one of the real-time Linux patches or distros, I'd imagine they'd handle pretty well. I believe the PC-104 boards are routinely used in real-time applications.
Reply to
Chris S.
I did not expect that RAM is so limited. So it will be impossible for robot to remember a plan of surroundings and way back of its trip. Is it possible to read/write data into free space in EEPROM from the running program? If yes, how slow is writing? oopic boards would fit great to start learning, anyway I would like to understand what can be done in the next step.
- what board(s) or combination with oopic board could be recommended to look at for such tasks as learning plan of area and keeping it in memory? - any links to existing robot projects or/and robot kits?
Thanks. Ek
"dan michaels" wrote in message >
Reply to
Ek
For what you're describing, I imagine you'll want to be looking at a controller board with a lot of RAM on-board, outside the cpu - hard to say how much you'll need, but I imagine planning/mapping/etc type activities will require quite a bit. Few of the PIC, oopic, Stamp, etc, boards will have this. Maybe some of the AVR boards, probably some of the 68HC11 family boards. ???? With the oopics you could hook up an extra eeprom and write data into it, but I don't know whether this will meet your reqs. ???? I always figured, if I ever got to doing those sorts of tasks, then I'd add another cpu board specifically chosen for those jobs.
Reply to
dan michaels
Thank you for your comments. 68HC11 looks interesting for me. I also found an interesting board (on
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suggested by Chris in this thread):
VIA EPIA MII10000 Mini-ITX + Netgear 108Mpbs Wireless PC Card + 512MB PC2100 DDR DIMM + flash memory chip or small hard drive
All this costs somewhere $400 and supports WindowsXP/freebsd/Linux. A little bit pricey, but with Gumstix price would be same.
The board allows adding web camera (USB) and video camera (firewire). That can be full fledged computer with wireless 802.11g.
The issue is to find appropriate controller that would support interface to sensors and servos/motors. Also how connect controller to VIA board.
Any comments to new configuration? Thanks. Ek
Reply to
Ek
Have you considered using a camera card for RAM? MMC is made all the way up to 1 GB and Secure Digital (such as used in an Olympus camera, for instance) can be formatted and used to boot up a computer; they are very small. You might have to hard-wire one to your board, but I am looking at a smart card as I'm typing this. It only has 16 data lines, plus 2 for power, and they are flat and should be easily soldered.
I would do it quickly though, I don't know how much heat one of these little things might be able to stand.
Michael Hearne
Reply to
Michael Hearne
I would rather do more programming than electronics :-) That's why I decided to make it simple (but more expensive) by installing mini-atx on the robot. So now I have ATX connected to OOBOT40 (oopic). Not sure if this is overkill, but it is for a separate thread.
Ek
Reply to
Ek
Compact Flash to IDE adapters are cheap and easy to use, your CF card looks just like a HD to your computer. However, typical OS read/writes to CF can wear out your cf cards... so.. Iv heard people loading up a motherboard with tons of ram, and creating virtual disks in RAM. Copy the OS from the CF card into a RAM Disk. This will let you write to the "disk" without wearing out your CF card.
Why do this at all? A spinning hard drive cant cope well with lots of random motion, very likely you will trash your harddrive prety quick! thats my $0.02
in
Reply to
danscott

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