Complete tear down and upgrades!

The time had come to do a teardown and inspection of R2-D2, to get a better idea of what was working well and what was not.

One of the major issues I wanted to address was the body sway I was seeing.  The source of which I thought was limited to the center foot having problems with its casters.

I also wanted to find a way to build some sort of shock absorber into the the center ankle or foot.  Whenever R2 rolled on uneven surfaces, the crash and clang was rather severe.

One thing I stumbled upon while looking for a way to solve this was a rubber muffler hanger.  This piece is about the size and thickness of a bar of soap.  Cut in half and it would not only fit well, but would also make R2's feet level.  For $4.99, it sure looked promising!

Finally I slowly took everything off, getting down to the frame.

One thing I noticed right off was a few of the screws holding the skins on were missing or very loose.

Upon inspecting the frame, I went around each frame rod and plate, checking for snugness.  The horizontal piece ath shoulder level was very, very loose.  Other frame rods required a few turns with the screw driver.  This was a big part of the swaying I was seeing.

To help stabilize the frame, I decided to put back two vertical frame rods that I had removed eailer.  The rods were located in a spot that would prevent hinges from being installed on the large, vertical doors on R2.  There are 4 large vertical rods that I removed.  To even the load, I put back two, with one in the front and one in the back, diagonal from each other.

The center foot was next. 

One thing that I checked first was the bearings that allow the caster to rotate.  It was very clear that they were in very poor condition.  When I tried to spin the casters around, they did so but not very freely.  Imagine 150 pounds (or more) on them and I can see why its been such a struggle to get R2 rolling. 

I beleive the problem is the holes I drilled too close to the groove near the bearings.  In order to mount the foot plate into the foot, the bolts had to pass thru the casters. 

The replacement casters are the same size as the previous ones, 2.5 inches.  They seem to be the same material, just a different color neoprene.

This time, rather than trying to drill through the casters at all, I came up with a better idea.  I decided to run 1 inch long (10-24) screws and using a lock waster and nut on each.  This way, when I bolted the mounting plate into the center foot, there would be 8 screws pointing upwards.  I placed the rubber muffler mount I cut in half in the middle of each, then slid the casters into position on top of them.

Without too much force, I then used a small washer and a lock nut on each until the casters were snug and level....now the casters have the rubber 'shock absorber' them and can ride up and down a bit as needed....

Once I had R2-D2 all back together, I had another thing to do....pick up the great Santa hat my Mom made!

Looks good, yes??

Getting ready to improve the center foot & ankle

A quick post for tonight...

Tonight I hit Lowe's to pick up some pieces I want to test fit into R2's center foot and ankle.

First, the rubbergasket is used in plumbing. Other builders have cut these up and used them as a rudimentary shock absorber. For $7, its worth checking out.

Also, I want to see if different casters work any better. These are 2.5 inches like the current neoprene ones.

I'll start working with these over the next few days. I have some other ideas I would like to test but I need to find the right pieces first.

R2 is home, survived his first outing!

R2-D2 is back home after spending just under a week at my workplace.

Last Friday R2 got to visit with the children in the Pediatrics Floor and Pediatric ICU. Over the past few days I've been battling a sinus infection so I was out a few days. R2 had the conference room all to himself! However word got around that there was an R2-D2 around and before you know it, staff and kids are showing up with camera phones! Ha! Awesome...!

Between some battle damage from the transporting process, R2 has some pretty good dings from banging into things. In this picture, you can see on the right side a bit of paint missing from a shoulder. That's from a poor attempt to get out of the elevator by gunning the throttle to get over the door lip. (The elevator is sporting a minor ding too, so the "fight" was a draw!)



As mentioned in the previous blog post, its time for a tear down to check everything out. Some of the skin screws have popped loose or jiggled out completely. R2 has a fair amount of body sway, mostly related to the center foot casters being problmatic. I need to log all the 'issues', video how its driving around now so I have a reference for when I make some tweaks.

Finally...if you think you find a great, cheap solution....be careful!

I bought these cheap, $9 moving casters as they were touted as each 'being able to handle 200 pounds each'. Well, take a look on the left side of the photo below....

The problem, asides the collapse of the casters under the structure, is that the wheels are tiny little plastic ones. They rub along the inside of their metal brace and due to their small diameter, get stuck and jam on the smallest of bumps and cracks.

While I would like to make something more elaborate, I now have a simple moving dolley. A rectangular shaped wooden structure with 4 large casters!

Anyone want 3 slightly bent moving casters? :-)

R2 makes his big debut on the EMMC Pediatrics Floor

Today, after much planning and work, R2 got to go to the Pediatrics floor and entertain the kids!

Due to privacy requirements, I didn't take any pictures of R2 with the kids. Plus, I was too busy driving R2 around!

The kids, parents and staff were all amazed to see a real life R2-D2 in person!



On the technical side of things, I have several things on R2 that I am going to try to improve.

R2 seems to have one NPC motor that is much stronger than the other. I used the RoboteQ software to test and monitor the motors on the laptop. The left motor is much more powerful than the right, so I reduced power to the left one. It still requires a lot of left input to drive straight. Upon tear down and inspection next week, I'll check the foot drives and belt tension on each foot.

The center foot has a shimmy. R2 struggles to straighten the caster wheels inside the center foot. It could be as simple as an axle too tight. We'll have to see and test some more.

Electronically, everything worked very well. The dome lights lost power when the power cable got yanked out. The cable fell between the dome and body while the dome was moving. A better way to route power to the dome , such as using a slip ring, will have to be considered in the future.

Battery power was fine, no issues there. The XBOX Windows gamepad system worked fabulously. It was fun to hand the kids the gamepad and let them trigger R2's sounds.

I had an awesome time bringing smiles to the kids, parents and staff. I had a LOT of great help from a lot of people getting to this point! Thank you all!

R2-D2 maintenance! Locking the ankles and checking the shoulder mounts out

One thing I knew I would have to do at some point was to figure out a way to lock the ankles into place. With the high-torque NPC-2212 motors and the stop and go movement of R2-D2, I was seeing a lot to rocking and swaying between the ankle and feet.

As others have suggested in their build blogs, they have made wedges and drill/tapped/bolted the wedge into place.

I went with the suggestion of Mike Senna and Victor Franco made: cut up some pieces from a plastic cutting board. Its thick, has a bit of flex to it and inexpensive. I found a $2.99 cutting board at Lowe's and as ironic as it sounds, cut it up.

Using some scrap paper, I made some simple templates to roughly cut out of the plastic.



Now cutting plastic with a Dremel is...well...a real messy experience. However, its the most effective way to zip it piece out, check for fit, file down a bit, check for fit and repear til you are please with the fit.

They aren't perfect but they do the job. After installing these and driving R2 around, there is a huge difference. After doing the test drive, I wanted to check so see how the shoulder assembly was holding up. I was curious how loose the nylon-insert nuts had become from all the rocking around.

Thus it was take-apart time to check the shoulders. I did find that they were a bit loose and while not dangerously so, I opted to replace the nylon-insert nuts and also added a flat washer for good measure. With the dome plate removed and the dome off, I checked for anything else that might require some snugging up. Everything looked alright, so now the batteries are all topping off their charges for this week's events.

R2's sound system

Getting R2's sound sysem rolling has been an interesting process.

Initially I wanted to do what many other builders have done, using a programmable sound device with an FM remote that could play specific sounds. The problem I had with this was the cost of the hardware and the limited number of sounds it could play.

To get by on Halloween, I borrowed my friend's Netbook for sounds. A Netbook is a mini-version of a laptop, with a 10" inch screen. It has wireless networking so I was able to command sounds to play from my laptop on Halloween.

I ran some ideas by my friend Randy since he is a talented, hobby programmer (he would ask I emphasize HOBBY). We've had some great brainstorming sessions and came up with a computer program that uses a wireless conrol pad, in this case a Windows wireless XBOX controller, to play sounds. As we go along, we keep adding and refining things (it may be completely different after I publish this entry!).

At this point, we have divided the sounds into 3 buttons. "Happy", "Chatty" and "Sad/Scared" which each have their own folders and sounds in each. When one of the buttons is hit, it randomly plays one from that sound category. But then we added a STOP button to cease the sounds. Then, we made an "Idle" mode, so that sounds in the "Idle" category would play a random sound every 45 seconds.

I have an 18 minute high-quality sound clip of all of the original R2 sounds. After hunting around Download.Com for a few hours, I finally found a utility that would allow me to cut up the sound file based on pauses so many seconds long. After setting the program to look for pauses that were less than a second, I suddenly had a lot of sound files to work with!

Originally, from the various downloads offered, I had about 30 R2-D2 sounds of good quality. Now I have over 240 in superb quality! (It took a LONG time to categorize those sounds!)

The setup has a few cons...the netbook has a small hard drive, only 4gb. Despite all efforts, this thign is always low on space thanks to Windows Update! I have had to do a lot of system tweaking and it seems like a daily battle to optimize the system setup. We have some ideas to address the issues...but its just a test setup anyways. The 1.5 watt speakers are "ok" but something more powerful, with a modest power requirement, would be better.

Here's how the test setup looks...



....close up...

More soon!

R2-D2 is moving around nicely!

Here's an new video clip showing R2 moving around with lights, head movement and such. Next up is getting the sound working, which my friend Randy Hunt is working on.....more on that another time!