I am looking for suggestions and information for a base for an outdoor mobile robot. I started looking for 1/10 scale R/C trucks but they seem to be too small for my application. I want to put on a mini-atx motherboard, dual cameras and a large gel cell battery and as far as I can tell r/c trucks will not be able to handle the weight.
One note my mechanical and machining skills are not very good so I would like to avoid custom work as much as possible (I prefer to concentrate on electronics and software).
What have you chosen as the base of your outdoor robot?
Most people custom make their larger outdoor-use robots. There aren't too many pre-fab bases for this application.
If 1/10 scale is still too small, how about a Power Wheels (or similar) riding toy, modified to carry your ITX board instead of a kid. They are motorized already, and at about $150-300 aren't too expensive for what they offer. Some mechanical modification might be necessary depending on whether you want to keep the steering system or adapt to something else.
I use a powered wheelchair, a Quickie G-424. Like you, I didn't want to try to fabricate something for my first robot. My G-424 gets around fairly well outside but can't climb the sloped curb on our street - even when I ram it while doing a wheelie. (There's something I could not do with the factory controller.) I suspect that being a mid-wheel model is a hindrance in this regard.
It does get around in our yard o.k. and can even handle some snow. I have gotten it stuck in a patch of small landscape rocks though. Hmmm...tire chains? Looks like there are a couple manufacturers who specialize in wheelchairs.
There are other powered chairs (tracked and wheeled) that can go through much more difficult terrain. You'll pay for it, but at least you can pick up the phone and buy a wheelchair. I tried to buy outdoor robot bases (iRobot) for years and got nowhere.
A medium duty system might be a childs battery operated car. The stronger ones might even have two motors so that you can use differential steering. You would still have to make your own electronic motor control system.
A motherboard is rather heavy duty for a robot unless you intend doing some on board heavy duty processing?
What are the cameras for? Remote viewing?
A heavy duty solution might be a secondhand motorized wheel chair. You can interface the control panel to the computer. The toggle stick for example might be controlled via two tiny stepper motors?
The ideal system IMHO would be a radio link with a PC if heavy duty processing is required. Development can then be done with the comfort of sitting at your desk.
makes for a remarkably "plug-and-play" solution. They even have info for using the "heavy duty servo" mode for actuating steering wheels.
When power is cheap (big batteries), it's a cheap and easy route to take.
The RoboteQ controller can drive the motors directly. It is incredibly easy. I'm still amazed at how well it works.
I develop sitting at my desk while my robot is wandering the garage/front yard/driveway. I have "heavy duty processing" available on the robot (and an 802.11b link) though. Having extra processing power is not a detriment.
I too have a (used, old) power wheelchair which I intend to make a robot base out of. The chair is a Quickie P110. Just wondering, do you know anything about the programmers for these chairs? I would like to reprogram the wheelchair controller for better response. I believe a local wheelchair shop can do this for me, but I would like to have the capability myself. If it's an RS-232/RS-422 comm link I can juryrig a programmer if I know the communications protocol.
First of all thanks for your replies and apologies in advance for the long post.
I am pretty early on the design of this robot so let me give you a bit more information on what I am trying to achieve. I would like it to be mainly an outdoor robot but if possible run it indoors when doing some testing. When I say outdoors I mean grass or dirt, I do not expect it to go over rocks or other obstacles. In the beginning it will work like an ROV but once I get it working I would like to make it more autonomous. Here are the sensors I am planning to put on (some I already have from my other robots):
- Two cameras for stereo vision (probably standard USB web cams)
- GPS receiver (DeLorme Earthmate USB)
- Inertial sensors (either build my own or get one from rotomotion.com)
- At least three sonars for obstacle avoidance
- Wireless communication to control laptop
All my previous robots had very limited onboard processing power, this time I would like to have more. I thought that the VIA EPIA M600 (not sure about the model) would do the job, this is a fanless, low-power
600MHz mini-itx with all the peripherals you would expect and even an I2C port. Of course all these will require substantially more power than my other robots (a 7Ah gel cell will do the job I believe).
Coming back to your suggestions, I will look into the toy car idea, the wheelchair sounds good but too expensive for my pockets! Let me know if you have more comments!
I thought about messing with the onboard controller. (I have the digital QTRONIX joystick.) It seems a shame not to use it, but the hassle of trying to discover the protocol and find connectors made getting a more appropriate controller a much better path to take.
I highly recommend just getting a RoboteQ controller. I know I sound like a commercial, but I bought an extra Quickie power harness, had it locally modified with standard power connectors, and it plugged right in to my wheelchair and worked the first time. That's worth a lot to me.
email@example.com (Vassilis) wrote "I thought that the VIA EPIA M600 (not sure about the model) would do the job, this is a fanless, low-power
600MHz mini-itx with all the peripherals you would expect and even an I2C port. "
VIa makes boards with three types of processors (c3, eden and nem......). The the eden processors are the cpus with the lowest power consumption although there are c3 processors that don't need a fan. The eden processor are (at least in the Netherlands) hard to find. The C3 processor needs more power but is faster en better for multimedia stuff.