Ive been wanting to build a Hanging Pendulum robot for the last 30 years
Technology (and inexpensive consumer parts) finally conspired to let me try and realize my dream.
Inexpensive 500 watt 48 volt 26" Chinese brushless bicycle wheels form the basis of my bot.
And the chassis is constructed from T6 aluminum plate and extrusions with stainless steel side forks and hardware.
The 2 intermediate plates are 3/16" black ABS.
The Bottom shelf is for 4 12 volt wheel chair batteries that total 92 lbs in weight and wil be series wired for 48 volts.
The intermediate bay will hold 2 Kelley reversible 48 volt 500 watt bicycle wheel controllers, a DC to DC 5 volt and 12 volt converter, an APM (later Pixhawk), a receiver, Telemetry and some assorted interface electronics for the Bicycle wheels hall devices and throttle.
The top shelf will support my HP Envy Laptop for Kinect and Laser Scanner interpretation.
A brushless gimbal stabilizing (and scannable) platform will be on top with a Kinect, laser scanner and FPV camera.
As it is, the chassis has worked out very well so far, I didn't manage to build myself into any corners I couldn't get out of and its is as robust as it looks.
Fabrication took more work than I had initially envisaged and most of the layout was simple manual markup.
As it is now, the wheels and bare chassis weighs 63.0 pounds and the battery pack will weigh 92 lb.
There should be about an additional 20 pounds of stuff in the first pass (Vision system but no stabilizers or arms), so it will weigh about 175 pounds.
This is not a light robot and you definitely would not want to get hit by it.
The 1000 watts worth of motors are definitely overkill, but I wanted the extra torque for operating at low speeds and the wheels I have chosen are very efficient when operating in the 20 to 50 percent power range.
Please feel free to comment and as I continue to make this operational I will post more about this either here or on subsequent Blogs.
Best Regards,
Gary
Comments
Also slight further update, Microsoft has completely dropped the ball on the robot development system.
Since Bill Gates fully left, Steve Balmer completely cancelled the project, so the "Robot Development system" is no longer a viable option.
Instead ROS and Linux are really the only way to go and they already have some support for laser scanners and Kinect 1 and the much cooler true 3D TOF camera Kinect 2.
Of course with the dismal showing of the Kinect 2 in the consumer market place Microsoft may be dropping support for that too.
Best,
Gary
Hi Esa,
I'm afraid I've been working on other things, but my initial plan was to use a Pixhawk for the primary control with an RC system and then add a companion computer (originally a PC, but now probably an Odroid or RaspPi2 for more advanced vision based navigation.
And yes the stock rover code should work fine in skid steer mode (so long as it is self balancing (CG well below wheel centers)
While this robot is mechanically feasible it is awfully large and potentially dangerous if it gets away from you, mine weighs well over 120 pounds.
If I was doing it over I would try to come up with a smaller lighter form factor.
Also the bicycle motors are a little impractical as this bot would easily achieve an over 30 mph top speed and yet has relatively low torque. (At 30 miles per hour it would be completely uncontrollable and would rapidly turn itself and everything around it into a disaster).
I will be getting back to it probably within a few months and I will post an update as a new Blog when I do.
As well as on my RobotsAreFun.com website.
Best regards,
Gary
Hi Gary,
Just wondering if you have an update on this robot ?
I'm planning on working on something like this and am wondering if you maged to get this robot going ?
If so what autopilot did you use onboard ? would the stock APM:Rover code work for this type of platform (in Skid Steer mode) with acceleration values reduced
Esa
Hi Dave,
One of the reasons this Bot is so big is to incorporate a full sized lap top which can run the Microsoft Robotics Development System software.
This suite contains drivers for both the Kinect and for a Hokuyo Laser scanner and provides a variety of autonomous and interactive examples.
The APM / Pixhawk will be acting as a controller board for the connected laptop for the first stage of development.
I am planning on having the scanner both stabilized and independently movable in the vertical access so it can provide a dynamically adjustable grid mesh scan.
Theoretically this should be easy, but that is not what I am expecting.
And Tero, nice balance bot, but a hanging pendulum bot behaves very differently than a balance bot (opposite in fact).
And mine is really big, I really designed it as a test bed for vision and manual task systems.
But the whole thing can can be built with simple stock metal components and hardware and no CNC tools are required.
You do need to be at least patient and at least somewhat competent with manual layout.
I have a drill press, a large (81") floor belt sander, bench cutoff saw, 48" foot press floor shear, and power floor hack saw which all came in handy, but the fact is you can do this all with a few hand held power tools if you want.
A good hand held electric drill could work if you are competent with it and you need at least a handheld electric jig saw to cut the aluminum and I really recommend a belt sander to round the edges and a die grinder (or at least Dremel tool) would also be good.
http://www.3ders.org/articles/20131029-b-robot-a-fully-3d-printed-s...
This is great. Simple and well thought-out design. I'm very interested in how the first power on tests go. How does the laser scanner interpreter work?
This is great. Simple and well thought-out design. I'm very interested in how the first power on tests go. How does the laser scanner interpreter work?
Hi Jesse,
That is 1" x 1/8" thick 6063 T6 Angle holding a 3/16" thick piece of 6061 T6 aluminum diamond plate on the bottom.
It really shouldn't have any trouble with 92 pounds of batteries, In fact should be good for well over 600 pounds static load.
And since I am not planning on high speed off road travel with this I don't think the dynamic load should be too much of a problem either.
If I was building a high speed off road bot I'd have changed a lot of things, It would have suspension for starters.
I'l be using heavy rubber mat underneath the battery and around the sides strapped in with two battery straps. (It will likely have an acrylic front and back panel as well.)
The bottom line is that this is a development platform and whatever isn't up to snuff will get upgraded and replaced.
At this point I am happy that the basic design seems like it should be functional and it is quite robust.
Best Regards,
Gary
it's lookin' good mate!! I would suggest that you either use thicker L section or weld that bottom joint. 95lbs of batteries exert an awful lot of force on the frame going over bumps... I suspect that that L section will fail at some stage as it's a little bit light... how are you securing the batteries on the bottom shelf?
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