Parallax Gas Robot in R&D
Ken Gracey
Posts: 7,392
Hello,
Below is a picture of a robot we currently have in R&D. This robot is awaiting a final flow control valve, so it is not running yet.·It consists of·a hydraulic system·with an engine and pump, proportional/directional valves for each side, and fluid brakes. Servos will actuate the valves and brakes. The front and rear wheels are connected by belt and the steering is differential. The robot's weight is about 75 pounds. There is no on-board charging system, though the battery capacity will be sized to exceed engine running·duration·with a full tank of·gas.
The objective is to·produce an outdoor robot capable of GPS navigation on grass or dirt, with an improved·power/weight ratio than full electric robots with batteries normally provide. The robot's cost will likely be around $2,000, though we really don't know for certain at this time (much depends on purchasing issues and a final cost estimate, but it will be expensive!).·This is our second prototype and we plan on producing a first production run this summer of 20-25 units if all goes according to plan this spring.
There will be no Stamps in Class text to accompany this robot, though you will receive detailed operating and mechanical instructions. You can put any processor or sensor on the robot platform you desire. It would be shipped fully assembled and bolted to a pallet, ready to be customized by our customers.
Our internal R&D secrets about this robot are now exposed. I think I've told you everything I can about this robot, but you're free to discuss it among yourselves if you find it of interest.
Sincerely,
Ken Gracey
Parallax, Inc.
Below is a picture of a robot we currently have in R&D. This robot is awaiting a final flow control valve, so it is not running yet.·It consists of·a hydraulic system·with an engine and pump, proportional/directional valves for each side, and fluid brakes. Servos will actuate the valves and brakes. The front and rear wheels are connected by belt and the steering is differential. The robot's weight is about 75 pounds. There is no on-board charging system, though the battery capacity will be sized to exceed engine running·duration·with a full tank of·gas.
The objective is to·produce an outdoor robot capable of GPS navigation on grass or dirt, with an improved·power/weight ratio than full electric robots with batteries normally provide. The robot's cost will likely be around $2,000, though we really don't know for certain at this time (much depends on purchasing issues and a final cost estimate, but it will be expensive!).·This is our second prototype and we plan on producing a first production run this summer of 20-25 units if all goes according to plan this spring.
There will be no Stamps in Class text to accompany this robot, though you will receive detailed operating and mechanical instructions. You can put any processor or sensor on the robot platform you desire. It would be shipped fully assembled and bolted to a pallet, ready to be customized by our customers.
Our internal R&D secrets about this robot are now exposed. I think I've told you everything I can about this robot, but you're free to discuss it among yourselves if you find it of interest.
Sincerely,
Ken Gracey
Parallax, Inc.
1000 x 750 - 175K
Comments
You posted this a little too late for me to buy my wife one for Valentines day [noparse];)[/noparse]
Actually 2K doesn't sound bad at all for that. I know a guy who runs R/C cars and I bet he has a LEAST that much tied up in them.
I wonder how much it would cost to ship to PA ?
Excuse me while I wipe the drool from my keyboard..... Mmmmm robot aaaaaggggg
Bean.
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John R.
Click here to see my Nomad Build Log
So… how loud is it? How fast? HP? Got tracks for it? What about floats and paddles (somebody’s got to pick up the decoys)? Where does the trailer hitch fit on? Can it pull me on my bike? Will the battery run headlights all night? Any interface to the hydraulic valves so I can hook up a dump bed, wood splitter?
In a man’s world where bigger is better— Mo’bot (sic) is definitely the best!
Very, very sweet. I better start saving my pennies.
If brakes and valves are servo driven, it sounds like operation (for the micro) would be as simple as servo control? What's the servo setup? One for each motor valve and one for each brake? Or are the brakes tied together?
Is there any way to determine speed in a close loop fashion? I'm thinking encoders here... I wouldn't want to ruin all that beautiful engineering with homebrew encoders.
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When the going gets weird, the weird turn pro. -- HST
You can call me Ken. You're right - the gas robot I made should have been what the robot above became. Truth is that I don't have any time to design production robots at Parallax, so this was done by a local engineer with a machine shop. I'm just playing around and learning as I go like many on the forums. This robot represents the wheeled design of what I wanted to make. To answer your question about control - yes - just servo control! Brakes are independent, too. There are many places to mount encoders: disc brakes, wheels, various pulleys, etc. The best way to determine speed may be GPS. You're right about the potential for damage - this could get expensive when you run a nicely machined robot into a square curb!
LSB, thanks! I picture it [noparse][[/noparse]several years from now] going to the local convenience store and returning with a loaf of bread in a basket. No, the battery won't run headlights very long - the 20W halogen 12V bulbs would quickly drain this battery. I suppose you could hitch a ride on it, or tap the hydraulics for more stuff. Whatever you want to do! No tracks yet, though I suppose we could create such an add-on. And as far as the dog is concerned, just be careful that it doesn't end up "dragging the dog"!
Ken Gracey
Parallax, Inc.
That Wabeco machine has been put to good use.Now that is awesome.
You have become a master machinist.. what is that· blue box on the front
Honda powered Robot..
Could not resists adding my Robot· Honda Powered as well
XR250 4stroke·light nimble awesome power and super reliable,
Picture taken in the high country here 2hrs above Melbourne
Once a month we take this animal out and let it loose..
Ronald Nollet OZ Australia
Don't take this the wrong way Ken , loose the brakes they are not needed with hydralics. You· should not need any gears or pulleys on your motors , direct drive them. speed can be controlled by flow and pressure
Brian
Post Edited (Brian Beckius) : 2/16/2007 4:13:49 PM GMT
Depends on how they have the controls set up. They may have went for an "open center" condition so that it could "coast" downhill.
If they didn't do that, and have an "appropriate" means of proportionally controlling flow to/from the motors, then I would agree that brakes are redundant, and may even create some problems with the power hydraulics.
In terms of other possible suggestions, I would also be somewhat concerned with the ability of the hydraulic fluid tank to dissapate heat during an extended run.· There doesn't appear to be all that much "reserve" volume, and the fluid will be make the rounds frequently.· Bigger fins may be in order.· (I'm assuming that the round aluminum tank on the back end above the pump is the reservoir.)
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John R.
Click here to see my Nomad Build Log
Post Edited (John R.) : 2/16/2007 2:32:38 PM GMT
·I have away of being pushy even when I'm suggesting stuff. Ken , I would look into not using brakes and direct driving your motors . It would be cheaper And easier to control.
Brian
PS .I have to do some digging in some books here , Hmmmm . This could be fun .
PSS. AWSOME Fabrication work !!!
Post Edited (Brian Beckius) : 2/16/2007 2:50:52 PM GMT
Ron, I didn't machine the robot. A local engineering and machine shop partner did it under our direction.
Brian, I thought the same about loosing the brakes, but it's not the case with this design. The robot has the ability to coast without brakes being applied, so the middle loop is open. I'm pretty certain we chose to use breaks in lieu of an additional valve on the internal loop. It also has benefits for R/C control. Keep the requests coming.
Thanks,
Ken Gracey
Parallax, Inc.
Any chance of getting an electric start in there?
Ken's other gas powered 'bot has inspired me to make a 'Hybrid Electric' platform out of an old Power Drivers (kid ride on toy), small portable generator, and a car battery. Will post details in another thread when I get the steering worked out.
Great Design Ken!
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Mike
I smell a little friendly completion here, how many horsepower.
Brian
We'll need to see how many of my design flaws Mike incorporates into his project first [noparse]:)[/noparse]
Mike, show us pictures!! Kid toys make great platforms for bigger robots.
Ken
Design flaws? Yup there will be plenty, in my version!
Right now I'm 'mocking up' the steering linkage, drill motor, bearings, and thread rod on a platform made out of MDF. Once I get all the kinks worked out, I'll replace all the MDF with aluminum.
Going to use Beau's idea of controlling a drill motor as a servo. Well enough about this in this thread, I'll post to a new thread this weekend, with some pictures. Goal of phase one is to make a big R/C car and then go from there.
Again Ken, Great Design, may have to start saving my pennies!
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Mike
Post Edited (Mike Cook) : 2/16/2007 10:07:22 PM GMT
·Doing some thinking, Hmmmm.....
Post Edited (Brian Beckius) : 2/17/2007 4:14:30 PM GMT
Plus of course, documentation discussing general maintenance. My internal combustion skills are good (I work on my own cars and 'cycles) but it seems like regular and proper maintenance on the 'bot would be key.
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When the going gets weird, the weird turn pro. -- HST
I'm kind of curious why you gave up on the motor/alternator one ? That seemed like a good plan and easier to work with than hydralics
Brian
I didn't give up - in fact Parallax just bought a new CNC mill so I can cut some more parts. I like the hybrid concept better as well, but here's the real deal. I'm a business guy at Parallax and designing stuff for sale isn't my main responsibility. So it's mostly for hobby and trade show demonstration purposes. But we need some larger robots, and they need to get finished and produced. For this reason we hired a local engineer and machine shop to finally make it happen.
My design will continue but at a snail's pace. It may never be a product.
You know, what's interesting is that a hydraulic robotic cost the same to make as a hybrid robot. You're either going to have motors and alternators with an engine, or pumps/valves with an engine.
Where did you get those tracks in the picture above?
Ken Gracey
Post Edited (Ken Gracey (Parallax)) : 2/17/2007 2:33:24 PM GMT
Those tracks are blower belts from race cars turned inside out .To make them work as tracks the drive wheel has to be a soft rubber. I made some drive wheels out of steel and sent them to a company in Michigan to have covered with rubber. I haven't started on this project yet , but I have been collecting the parts for awhile. I thought your hybrid was a perfect match for tracks .
Brian
PS. They might cost the same to build ,but wires don't leak oil . :-)
Post Edited (Brian Beckius) : 2/17/2007 12:41:16 PM GMT
"Those tracks are blower belts from race cars turned inside out"
That reminds me of the same type of belt used for the reduction drive to the propeller of an Ultralight aircraft.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Thay are made by same company , just a little wider.
Ken,
Back on the R&D robot , awsome job . 2k will be a steal of a price . I am a little concerned about the hydralic drive system. But you guys have allways amazed me, so I'm sure that everything will be great.
Brian
ps. posted better track picture
Post Edited (Brian Beckius) : 2/17/2007 4:15:39 PM GMT
Marty
I can't see the gear on the wheel , but·if I did my calculations right based on those hydraulic motors your going to need·wing's on that baby
40-50 mph ???
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Thank's Brian
www.truckwiz.com
·"Imagination is more important than knowledge..." ·· Albert Einstein
Post Edited (Brian Beckius) : 2/20/2007 6:13:40 PM GMT
The founder of BEAM robots mentioned his frustration at seeing so many people build 'rolling garbage cans'. But the real source of his frustration is that mere battery driven robots will never have the sustained available horse power to do what larger Bots really can do.
In this setup, I can easily see adding an arm or boom that really has substantial lift capablity and using computing to do quite sophisticated navigation and positon control.
In other words, it feels like the jump from a TRS 80 Color Computer to an IBM clone.
With the better and larger platform, projects can leave the bedroom or workbench and really come alive in a workshop or field.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
About 10-15. There's a small gear on the engine connected to a larger gear on the pump. We can make it faster or slower with two gears, but there shall be tradeoffs for speed and turning torque.
Ken Gracey
Them look like high speed motors.
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Thank's Brian
www.truckwiz.com
·"Imagination is more important than knowledge..." ·· Albert Einstein
Post Edited (Brian Beckius) : 2/28/2007 3:54:28 PM GMT
Interesting concept.
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There's nothing a good wack with a hammer won't fix
Darn I let the white smoke out again