Dale's Wheel and Adapter Photos

Dale 08
Keith Rowell Design

Dale 07
Keith Rowell Design

Dale 06
Keith Rowell Design

Dale 05
Keith Rowell Design

Dale 04
Keith Rowell Design

Dale 03
Keith Rowell Design

Dale 02
Keith Rowell Design

Mascot Input at the December Meeting

We got some good feedback on the Mascot Robot at the december meeting, and there was an impromptu "Mascot design / BS" meeting afterwards at the nearby Dairy Queen.

Comments:

Provide Modularity - This is an effort to make the bot easier to maintain and modify in the future. With different people working on different parts, parallel tracks can be taken, different configurations explored simultaniously, etc. The controller that First uses was discussed because it provides Pendant, MCU and RF control . Does anyone have access to one of these from a retired First Bot? Something to think about is how to make not only the electronics modular, but to standardize on a way to make the mechanicals modular as well. Initially I will just proceed with simple triangle and rectangle modular sections that can be joined at the rotation axis' where the articulations join. (does that make any sense?)

ATmega - Mike Panetta offered two ATmega boards to the project.

Provide space for optical encoder - John Scott has offered to provide "optical mouse" encoders for the bot so space must be provided in the design. I'll put that into the CAD file once results of Dale's modifications come in.

Power transmission - Dale Heatherington took the gearbox and wheel home to try out some different coupling ideas.

Discussion - Discussion spun outward from there into subjects like laser obstacle avoidance ( Home Depot has a new laser range finder $400 ), Ultrasonic local GPS "LPS" schemes (this one is a ripe fruit and not too many others have attempted it), and many other subjects.

A couple of ideas I found particulary intresting. One was to investigate adding a very high level programming interface like Logo ( FlowCode was reccomended by Mike Lynch) so that newbie club members could jump in and get programming quickly on the mascot. Another idea was the posibility of making the mascot "balancing". There are more and more examples of this on the web and in other clubs, and proven code is available. The cost of the required gyroscopes and accelerometers seem to be the main barrier, but this is bound to be a parallel track in the future as those components become available.

EZ Roller Photos

ez roller 03
Keith Rowell Design

I've uploaded some photos of the ez roller kit from Solutions3. We have two of these and more than enough motor controllers to run them.

ez roller 02
Keith Rowell Design

ez roller 01
Keith Rowell Design

Solutions Cubed Inventory

EZ roller from Solutions3
Keith Rowell Design

EZ roller wheel kit x2
Motor Mind C dual controller x1
Motor Mind B single controler x1
Micro PID Position controller x1
Motor Mind C carrier board x1
Icon interface Module x1
Icon H-Bridge x1


Link to the motor mind spec sheets
http://www.solutions-cubed.com/Solutions%20Cubed/Products2003.cfm

I think the Motor mind C is the only one that controls two motors, you guys might want to check the specs on these parts. The EZ rollers are very nice. The wheels are about 2" dia foam, I wouldn't put more than 6 or 7 lbs on them but they have a very stylish "speed racer" action going on.

New Parts and New Designs

emergency stop x1
Keith Rowell Design

We've got lots of new parts this week and bold new designs.
Lots of parts are comming this week, forgive me if I miss any;

New Parts
Emergency Stop Button Jay Cross
Fuse Holders x2 Mike Lynch
12vBatt x1 Mike Lynch
1"SqTubing Mike Lynch
from hand truck, includes removable handle
1" round axle stock Mike Lynch
3/8" round axle stock Mike Lynch
retainer caps for same
10"wheels Mike Lynch
4" wheels Mike Lynch

more?
Clint Bridges also gave me the Solutions Cubed box. It's got nice stuff, but I haven't drawn it up yet. I'll report on that next week as time allows. Looks like we are going to wind up with more than enough stuff to build two bots, maybe a Kangaroo and it's Joey?

Still Needed

Castor wheel
Sheet Stock for frame and mounting of circuitboards and such, perforated would be ideal
Sheet plexi Stock for shrouds, mounts, etc.
MCU
Sensors
ideas!


Progress Feels Good
It's been great to see the participation and intrest in this mascot project. I could "re-design" forever, it's in my nature, but I know some people want to get started as soon as possible. I believe Mike has plans to start the hub modification soon and needs a lathe for part of that process. I will have access to one in January. Anyone else anxious?

Next week I will have the "Solutions3" inventory online and maybe some of you guys could look into what parts you would like to incorporate into this bot, and what kind of #2 bot you might want to undertake from those parts.

Also, these CAD files are very convertible. I can export the model in almost any CAD format. Anyone who wants a copy, just email me: rowell@mindspring.com. I would host the cad format files in a central location if it were convenient, and I've looked into it in the past. That collaboration tool hasn't been made as convenient or cheap as the "blog" format so far. I'll bark if that changes.

Just one more thing. Some of these used parts are skuffed up and scratched. If anyone has experience with this new "plastic" spray paint, or has an opinion about colors and "styling", please comment. I can imagine using the dark gray and pale yellow of the AHRC logo. Keeps the theme going. For more color and style ideas, it's very usefull to email a photo showing the finnish you like. I can "pick" these from the photo and use them directly in the rendering program. Seen any cool machinery lately that you'ld like to emulate? Is this going to be industrial grunge like the terminator? shinny like C3PO? or something fancy like the "lost in space second generation"?

fuse holder x2
Keith Rowell Design

hand truck mode with handle attached
Keith Rowell Design

From all the input we've gathered, it's obvious that transporting the robot from one place to another is of primary concern. The large 10" wheels would allow it to move over moderate obstacles, even low curbs (not withstanding castor wheel size). Ultimately it has to get stuffed into trunks, and get moved around before and after the presentations, in the most user friendly manner possible. After looking into a folding design that would fit into a tunk, the fold out castor bracket and wheels presented themselves for double duty. Upright it's a castor for the robot, upside down, its a bracket for holding stuff "hand truck" style.

Thanks to Mike's keen insight, the "outrigger handtruck wheels" idea provides easy portability to and from venues.

My original thought was to use the main wheels for both robot locomotion and free wheeling transport. But the gear boxes are impossible to move from the wheel end. I thought about cotter pin locks and electric clutches, but I think bypassing the problem entirely with "extra wheels" is going to work best.

hand truck mode / castor / bracket open
Keith Rowell Design

Here we see the castor bracket in the open mode. Makes a nice rack for holding other robot presentation stuff like chargers, computers, who knows what. The handle is removable and would mount into an extension of the primary frame, allowing for fairly rough handling vs. pushing the bot/hand truck around holding onto unfolded articulated joints...

side view / robot mode
Keith Rowell Design

With the handle removed and the bot turned over 180deg, the castor now rests on the ground, the weight of the battery is between the floor contacts, and the handtruck wheels are up in the air. The handle is removed for the demonstration mode.

castor open
Keith Rowell Design

This image provides a better view of the partially open mode. All views show the new 10" wheels, 1" axle, 12v battery, 1" square tubing frame, and fictitious castor wheel.

side unfolded
Keith Rowell Design

Adding another articulation, torso like, gets this particular arrangement up to 26". Not very big so far. I've minimized the distances involved in order to get it into a trunk. The frame is stout enough to carry more weight, so we should think about increasing the size as best we can, and still keep it in a managable "folded" dimension.

This begs the question, "how small of a trunk does it have to fit into"? Anyone what to volunteer their trunk dimensions? I'll check mine for a miatta, but I can tell you it's probably already to big for that...

A third articulaton would resemble a head and arms. Any ideas at all that you guys have on these, please post a comment. It keeps things moving along if we get alot of opinions early. Saves on dead ends...

fully unfolded
Keith Rowell Design

We can get very compact meshing of parts in the closed mode, so we can go ahead and be bold for now in regard to adding stuff like head and arms. Even if we don't implemet these right away, designating space for them now is the ideal path.

I have some ideas about the articulated joints, perhaps motors, or perhaps just locking pins. I prefer the motorized unfolding scenario, but Clint and Mike Pannetta have more experience with that and can definitely give some good feedback on that.

The current scenario shows the electronics in the "torso", batteries and motors in the "base", and sensors ect. in the "head", end effectors in the "arms". Comments please.

modified hub
Keith Rowell Design

hub assembly
Keith Rowell Design

The discussion of tire size and torque has been lively, and Dale has kindly volunteered to evaluate the torque vs. tire size for our particular configuration. "Eyeball" estimates seem to bear out the 10" tire size for this gearbox. So I've included some plans for connecting the 10" tires that Mike has.

Some evidence that 10" might work are; that the kiddie cars these gearboxes come from use 10"-13" tires; it's almost impossible to stall by hand; and the ground clearance of the gearbox using 6" tires is minimal. 8" might be ideal if we had any.

The 10" tires Mike has offered are pneumatic with a plastic hub, very nice. Theyre wider than the 2" "dummy" tire I had in the model last week. Mike has a plan to modify the hub so that those two inches are again removed from the width, maintaining our 22" approximate width. This modification ivolves casting a plastic "interlocking" hub that molds to the cavities of the gearbox hub and the tire hub, "lovejoy" style. We don't have lug nuts or wheel locks for this larger shaft, our plan to date is to weld washers on the in-board side, and use cotter pins and washers on the outboard side.

Motor Controllers Donated

I’ve got a couple wheelchair motor drivers that I bought quite a while ago that I’ll donate. I’ve never used them but I’m pretty sure they are good for 40-50 amps. I’ll dig them out and get you the dimensions.

Ringo

motor controllers
Keith Rowell Design

Thanks for the controllers Ringo. I've shown them blocked in green. The size is 3.75 x 5.5" with a 1" guess at the height. Image shows relative size of motors to boards. Specs are here:
http://members.tripod.com/~divelec/hbridge.html

Axle Shaft Contributed

I found a shaft that may work well for the Mascot. I've included it in the following images. I'll bring the partial assembly to this month's meeting.

Mascot Parts list to date:

Motors with gearheads___________________________Mike Lynch
Shaft, bearings, wheel locks ______________________Keith Rowell
Motor controller boards __________________________Ringo

Mascot Parts wish list:

wheels
frame material
power
controller
sensors

Images of Shaft, Bearings, and Mounting Hardware

bearings
Keith Rowell Design
The bearing OD is 0.688"
I have 5 of them and expect to use two per wheel which leaves one spare. This configuration should allow all the weight from the shaft to be carried to the wheels with minimum friction.

friction locks
Keith Rowell Design

I have 4 friction locks but we may get away with using only 2. They consist of a split sleeve that is threaded and a nut. Tightening the nut locks the location. They fit the shaft perfectly. They're currently attached to a larger OD metal tube and will have to be cut off. I'm looking for volunteers who want to cut these, I think a lathe will be required.

22 3/8" wide
Keith Rowell Design

I found a nice ground stainless steel shaft that may suit the mascot's needs. It's only 22" wide so it should make it through most doors easily. The OD is 0.311". I have bearings and friction locks to match the shaft. These all came from an old pen plotter so they're quite fine.

4' high and rising
Keith Rowell Design

I added a virtual box to represent the posible body mass of the bot. This gives a proportional reference as to the scale of all the parts togeather. Shown here the bot is 4' tall and 22" wide and deep.

new shaft and bearings
Keith Rowell Design

The bearings I have are mounted in these very convenient brackets. There are 5 of these as well. The brackets are aluminum. They're only shown as an alternate. If we mount the wheels on bearings, the shaft doesn't need to turn and won't need bearings at the frame mount.

First part for the AHRC Mascot drawn

Mike's Motor

This motor is from a child's ride on toy car. Mike can correct me but I think it's 6volt. It looks like the minimum wheel size is going to have to be 6-8". The rib is there to support weight, so the robot frame should go there I guess. We should do some tests on the motors to see what their power characteristics are.

Ringo volunteered a motor driver circuit that is more than powerful enough for the job.

I think the 4 main design objectives for a "club mascot" should be:

1. light and easy to transport
2. big for visual impact
3. flamboyant, showing off, technological cleverness to be proud of
4. cheap, cheap,cheap


Pretty much all development ideas are graded on these criteria, meeting three is pretty much a shoe in but very rare. Hitting two of them is very good indeed. It's always a trade off. While formulating your ideas about how we should develop our "design by committee", think about these objectives.

Everyone's ideas and input are vital, don't hesitate to comment. Your opinions drive the design process. Vote early, Vote often.

I expect the process to take about a year to complete from idea to working bot. The process I envision is an iterative process where I take the comments and sketch them in and present them back. We can go through alot of options this way quickly. Lets give it a try...