Drive system jerkiness is all fixed. The problem was the AX3500 and not a Vex compatibility issue. The board had a dry joint on the main power control tab which was causing a short. The speed controller thought the battery was low which cause the fail safes to kick in and turn everything off to avoid damaging the Mosfetts.

I’d gone back and forth on the phone with RoboteQ for a few days, and finally they just overnighted me a new board which fixed the problem instantly. While I was removing the cables to send the old board back the tab connector popped off the board totally.

In the process of troubleshooting the problem, they also convinced me to reconfigure my batteries to have a dedicated 12V supply to the board rather than using a single shared 12V supply for everything. They explained that the symptoms I was seeing were very similar to a low battery problem due to the motors drawing too much current.

I’m probably going to keep the batteries separate for now, but will have to rethink the wiring and my fuse block as I was hoping to just get away with one battery feed which also made charging easier.

The real worrisome thing is he’s way too fast and really dangerous. He can zip around at lightning speeds and can plow through most obstacles because of his weight. I may need to have a fast/slow switch.

He’s also shacking himself to pieces and has already dropped several screws.

I received my center foot on Friday and it was the last structural part that I needed to get R2 on all 3 feet. So, my goal for Saturday was to get him running around under his own steam by the end of the day. I still needed to wire in the RoboteQ AX3500 speed controller which controls the drive system.

I added a power strip to the inside of the back mounting plate to connect all the grounds to and set about wiring things up.

I then did some basic tests of the 3500 and noticed something strange. The motor would run for a second then stop for a split second then start again, like it had a slight tremor. Message code on the 3500 status panel flickered from motor direction information to an ‘8’ – which means under or over voltage. I suspect it’s a low battery. I hope it’s not a Vex/RoboteQ incompatibility problem. I suspect I may need to add a second battery dedicated to just controlling the 3500.

I then worked on trying to get the center foot assembled and attached to the frame. But there was a problem, I was missing the pack of hardware. A quick trip to Ace fixed it, but I couldn’t get the exact parts and had to improvise on the standoffs.

Like the outer legs and feet the new foot was a snug and it took some cajoling to get the pivot point to fit.

Now that the center foot/leg was attached I was excited to think I was close to getting him mobile.

However I really shouldn’t have rushed as much as I did. What followed was a bunch of silly mistakes which cost me a lot of time. Luckily no harm was done and I learned a lot in the process.

Even in my haste to get the legs on and the motors hooked up, I’d remembered that I needed to lock the legs somehow. I’m not going to be using the satellite motors to do 2-3-2 at this points, and one of they’re jobs in the design was to lock/hold the legs in place. So I knew I needed to figure something out, but I thought it wouldn’t hurt to skip this step just for now. Boy was I wrong!

At the same time I also had the drive wheels in the back of the feet, and they weren’t always touching the floor. I’d also forgotten to reverse the drive wires on one motor.

As you can imagine his first steps were not pretty to say the least and he jerked around because of the RoboteQ battery problem, and his legs went in opposite directions. It was a total shambles. Luckily I didn’t have the camera handy for a photo.

I also needed to tension the drive belts more which meant that I had to partially disassemble the feet again. I’m beginning to realize it’s a major pain to unscrew so many bits just to fix one thing.

After stripping him back down and fixing the problems and locking his legs back in 3 legged mode I gave him another spin and here he is. He’s super fast, but I really do need to figure out the battery/undervoltage problem that makes him stop/start/jerk.

Once I get the RoboteQ speed controller working correctly this thing is going to scream.

It’s been a long evening and I spent most of it working on my Front Logic Display. It’s something I’ve been putting off for months hoping it would either go away or a work around to my problem would magically come to me.

The problem is that my aluminum surround from Doug Olson does not fit the cool front logic electronics without going through some major surgery.

The surround is a one piece design and looks great, but it’s very precise in the way it fits. The more traditional two piece surrounds people had been using are more forgiving and you could angle the boards away from each other to get it things to fit.

So as I said, I’ve been avoiding taking my soldering iron to the delicate circuit boards for months, but it had to be done and tonight was the night. Without it I’m totally blocked on the dome. Luckily I only needed to separate one of the pair of boards.

I think if someone was still offering the front logic electronics then I wouldn’t have been so fearful of screwing things up, but I didn’t have the luxury of being able to fall back and simply buy a new set.

It took me hours to get it done and the good news is they still worked at the end. I’m not going to go into the hack job I did in fear that somebody may copy my method. But the tools used were soldering iron with a nice new tip, a de-soldering pump, one of those helping hand gripping thing and finally a small pair of pliers/wire-cutter.

Tomorrow I’ll get the surround fitted to the dome.

So, without further ado I present my new improved logics –

Click here for photos on Doug’s website of the logic board the surround.

The sound the little RF Receiver made every time I pressed the remote was really bugging me, so before going to bed I decide to remove the little ‘siren’.

I tried searching the internet and even found the new support forum for the product, but nobody seemed to know if the bleep could be turned off programatically, so I decide to simply remove it.

The siren or buzzer is located in toward center of the board

I used a de-soldering tool to suck out the solder

I soldered in some wires just in case I need to re-attach the siren later to change the RF code. Sorry it’s such a bad picture

Much better 🙂

02/10/08 Update – Here’s the board with an LED added in place of the buzzer (don’t forget to add a resistor on the positive leg. Resistor size will vary and depends on your LED. Source voltage should be 12V, so as an example given a 3.3V LED with a forward current of 20mA, you’d use a 470 ohms resistor but something bigger will work too, but the LED will be a bit dimmer.)

Another big step forward tonight and I’m not really sure where to start or if I can remember everything I did.

Maybe it’s easier to say where I’m at – I now have a lot of the electronics installed in the body, from fuse block and power distribution to the speed controllers and sound system. I can now control the dome and periscope from my Vex transmitter and trigger sounds with my RF remote.

There was a lot of stripping of wires, routing them, testing, and moving stuff around to make it all fit on the back panels. I also installed a second Vex in the dome to control the periscope, and eventually it’ll control some servos on the pie-panels.

From the photo it really doesn’t look like a lot but there’s a lot packed in there

I’m now realizing that it may not be a good idea to run R2 around naked / skin-less at C4. I could easily see someone pulling on the wires and frying something.

Here’s a quick demo video as well.

You’ll notice in the video that the periscope doesn’t run up and down smoothly and it chatters. Some of it is due to the speed the motors run at which I can limit in the Vex, but there’s also a lot of play in the lift mech screw system itself which I need to fix somehow.

I still need to wire in the RoboteQ speed controller which will drive the feet, but you can see it at the bottom of the frame.

One problem I noticed again is that the Vex in the dome has problems receiving a signal. This maybe a big show stopper unless I can route the antenna somewhere else.

The 12 channel RF Remote also has a “problem”. The new models have a little speaker/siren on them which makes this awful bleep every time you press a button on the remote – I’m sure for most applications this is fine, but for R2 it’s got to go. You’d think it could be disabled easily, but I can’t find anything. I’m going to have to fix it before it drives me nuts.

I just upgraded the gallery software and now my thumbnails are all screwed up. Apologies while I go back and fix each post 🙁

My CF3 Sound Board arrived today as well as the 5″ horn speaker from Parts Express

Damn is this thing loud or what? Gerard had talked me into getting a horn speaker and he was right, it’s perfect. I’m going to have fun blasting this thing around C4.

The only issue is ACS were out of stock of the add on CF3 Contact Sense 24 board, so I’m limited only being able to trigger two banks of sounds for now.

Related Posts: 

• Mounting New Speakers
• Sound System Work

Got my pass today for Celebration 4 🙂

It only feels like last week that I was posting something similar about C3.

They did a real bad job of laminating it, but I’ll be swapping it for a volunteer pass anyway.