Summary of work and events for June 2008

• Futaba Setup and Tweaks
• Futaba 10C Arrived – It’s a 10 channel 2.4Ghz FASST spread spectrum capable receiver and a big step up from the Vex transmitter I’ve been using.
• RoboGames 2008 Report – the weekend was jammed packed full of interesting people and very cool things – like talking with the engineer who worked on the NPC motors many of us use in our droids, or hanging out with the Orb Swarm folks or Grant Imahara from Mythbusters, or getting some inside info from the engineer who maintains the machines that spin our aluminum domes. Artoo even got in on some battle bot action in the arena and lived to tell the tail.
• RoboGames 2008 – Day 1 Highlights
• Trip to Ace
• RoboGames 2008 This Weekend
• Dome Electronics Rewire
• New Larger Casters and Angles
• Center Foot Wedges
• JAG Center Foot Mod – Lip/Skirt
• We’re in Bantha Tracks this month
• Battery Terminals
• Caster Fix and Test

Spent the last few days playing with the new Futaba 10C transmitter.

I had to re-calibrate the joysticks with the RoboteQ AX3500, and took the opportunity to review my speed controller setup, and tweak some of the parameters. After I was done looked like something like this –

Control Input: RC
Motor Control Mode: A and B Mixed
Input Adjustment: Logarithmic Strong
Amps Limit: 60
Acceleration: 682 (milliseconds)

I changed the Input Adjustment to Logarithmic (from Exponential) and decreased the Acceleration Delay to 682 ms. This controls how fast Artoo reaches his maximum speed and time to stop. I found that anything lower made him too jerky as he tries to stop on a dime. Both these parameters will make Artoo a little bit more responsive.

On the Futaba I increased the end points on each of the servo channels to 140%, but I suspect I could have left them at 100% due to the joystick calibration on the RoboteQ.

I also had had to reverse the direction on some of the channels.

I’ve managed to get the signal Fail Safe to work on the Futaba. Many of the older Futaba can’t do this, or at least not on all channels. For example, I know the 7 ch 2.4Ghz receiver can only do it on channel 3/Throttle. Which makes sense for airplanes, but not very good for robotic applications.

The default setting on the 10C is “Nor” which will set the receiver to continue to send the last good signal received out to the servo, or in my case the speed controller. This would cause the droid not to stop if I ever lost power on the transmitter or it’s link to the receiver in the droid.

Hoping that I’ll never need to use it, but at least it’s setup now.

As a side note, I’d almost went with an RC setup from Spektrum which offer a separate receiver (BR6000) specifically design for robotics, but it’s only 6 channels and I’m not crazy about the Spektrum transmitter setup, and really liked the extra knobs and sliders on the Futaba 10C.

I’ve also discovered that the extra FM antenna on the 10C is easily removed, and has zero effect in the transmitters operation. I was suprised to even see it installed when I got the unit. I’ll need to make a plug to fill the hole.

My Futaba 10C arrived yesterday. It’s a 10 channel 2.4Ghz FASST spread spectrum capable receiver and a big step up from the Vex transmitter I’ve been using.

It’s the newest receiver from Futaba and positioned right in the middle of their higher-end line up and very competitively priced. I’ve had it on back order at Tower Hobbies since late February and the price was around $580 after a coupon and shipping and handling. Compare this to almost $1,300 for the 12 channel Futaba or $2,200 for the 14 Channel, I think they have a winner on their hands – plus both of which are 72Mhz out of the box and will costs several hundred dollars to go to 2.4Ghz.

A couple of reasons for my upgrade

• I’m tired of having channel conflicts at events and the 2.4Ghz system will fix this problem. For most builders it’s probably not an issue as you’re probably the only bot at an event, but I seem to be at a lot of events where there maybe dozens of RC devices being used, and often run into trouble.
• The Vex transmitter was pretty bulky and hard to hold – it’s done me well and I’ll need to couple the Futaba with a micro-controller for some functionality I had planned for the Vex micro-controller.
• The 2.4Ghz antenna is much shorter and the range is supposed to be better, especially indoors.
• I’ve experience a slight delay/lag when routing the control signals thru the Vex microprocessor – there was no real way around this with the old setup.

The 10C is comparable to the older Futaba 9C that many builders use, but it’s 2.4Ghz spread spectrum out of the box rather than 72Mhz, and it has the extra channel. However the case is all plastic and I’ve already managed to ding it. I suspect the 9CAP will be discontinued at some point as it has issues with upgrading to a full 9-ch 2.4Ghz system. I almost bought the cheaper Futaba 7C ($280 at Tower Hobbies), but the 10C had some extra featured I really liked, in particular there’s a lot more switches, knobs, sliders and dials to use on opening doors and lifting things.

It more of a pro unit and can also switch between 2.4Ghz spread spectrum and regular 72/75Mhz bands using standard Futaba modules, whereas the 7C can only be 2.4Ghz.

The 10C weights in at 2lb 4oz, about the same as my Vex transmitter, which surprised me. The 10C feels much lighter in my hand, but it’s probably because it’s less bulky.

It came with a tiny R6014FS 14-ch receiver, but only 10 of the channels can be used with the 10C. It’s also compatible with with some of the 7-ch Futaba FASST receivers.

A word of warning on the new Futaba receivers. Whereas many previous receivers offered a signal output of 3.0 Volts, the latest generation of ICs has been designed to operate at the lower voltage of 2.7 Volts in order to increase their operational speeds.

My initial tests with the RoboteQ and Dimension Engineering speed controllers was successful, but your mileage may vary and worth checking with the manufacturer before making a purchase.

The plan right now is to replace the entire Vex microprocessor sub-system with either PIC, PICAXE or Arduino micro-controller. I’ll probably directly connect the Futaba receiver to RoboteQ drive system speed controller, and eventually route all the other channels thru the micro-controller to help automate some of the functions.

I’m really not sure where to start with my RoboGames coverage – the weekend was jammed packed full of interesting people and cool things – like talking with the machinist who worked on the NPC motors many of us use in our droids, to hanging out with the Orb Swarm folks or Grant Imahara from Mythbusters, or getting some inside info from the engineer who maintains the machines that spin our aluminum domes. Artoo even got in on some battle bot action in the arena and lived to tell the tail.

The event is held at Fort Mason in San Francisco each year and attracts thousands of people from all over the world. I was in attendance all 3 days with support from my friend Richard, and Gerard was there on Saturday with his R2.

The games themselves cover everything from the traditional battle bot arena tournaments, to robot soccer and sumo fighting. There are also special categories for art and bar tending robots. Maybe next year I’ll enter Artoo into the latter. In total there were 70 different competitive categories.

Artoo was a big crowd pleaser as usual, and many photos were taken with his admiring fans. My favorite was this one I found on Flickr by inkyhack.

Read the rest of this entry »

I had a kick ass day at RoboGames. There’s way too many things to post about, but thought I’d throw up some photos.

The highlight has got to be getting in the arena with some of the battle bots.

R2 managed to flip this guy over using his own weapon against him

There were also a lot of cool art robots there, like this one serving beer

More photos in the gallery.

The good news is the new 3″ casters are working out great.

Big thanks to Dave and Simone for being great hosts to the group.

I’ve been busy getting Artoo ready for RoboGames this weekend, and needed to buy some bits and pieces at the local Ace Hardware store in Pacifica.

I thought I’d finally take Artoo over for a visit. Dave the owner is a big Star Wars fan, and I’ve gotten to know a lot of the staff really well. They’ve always been super polite and put up with my crazy questions and ramblings when I’m trying to MacGyver something.

I also figured this would also be a good test of the new wheel/caster setup before I head out for a long weekend at RoboGames.

To my surprise the new casters were much better on the van’s loading ramp, and made easy work of the asphalt parking lot. He had a spot of bother with the big door jam going into the store, he almost made it over but not quite. On the way out I approached it at and angle, and after a bit of wiggling of the joystick made it out without me having to lift the front foot. I really don’t think the omni’s would have made it either, so right now I’m more than happy on how the wheel casters performed.

The visit turned into a bit of a mini event with lots of customers interested in knowing more about my creation – and I proudly told them how much Ace product was in him.

We patrolled the aisles searching of spare parts

When stumbled upon Lee at the hardware section – there’s probably 100’s of screws in Artoo from these bins. I also have to thank Lee for special ordering me some of the ‘mythical’ 3 inch casters.

On the way out we bumped into Dave, the store owner. We hung out for a while and talked about his love of Star Wars and how I envied all the resources he had at his disposal to build Astromechs – maybe he’s got the bug? I’m not sure 🙂

The 5th annual RoboGames, the world’s largest open robot competition, takes place this weekend, Friday, June 13th through Sunday, June 15th at Fort Mason Festival Pavilion in San Francisco.

The R2Builders Club will be in attendance on Saturday, this will be our second year at this very fun event.

If you’ve been following along with the blog you’ll know that the electronics inside the dome have evolved a bit over the last 12 months. I’ve added more stuff, moved to a slip ring system rather than separate batteries, and in general created a wiring setup in the dome that’s not perfect and hard to maintain.

Over the weekend I spent a couple of hours trying to simplify and reworking the dome electronics and thought I’d post something on the path I took to get where I am right now.

I’d originally had the various components like batteries, RF Receiver, RC Receiver, Power Board all laid out on the dome base plate – and routed power up into the actual dome with a detachable “umbilical” cord containing the 9V, 12V and 24V. Inside the dome was a terminal block that the various LED boards attached to.

To regain the space for adding the periscope, fire-extinguisher and other gadgets I then moved to stacking the electronic boards in a carrier – also located on the dome base plate.

But over the last few months I’ve been having problems with loose wires In the dome. I’m using the European style terminals blocks and no matter what I do the wires eventually work loose. Not enough to cause the lights to fail totally, but enough be annoying and make them blink or reset when driving around.

I was going to replace the blocks with the more traditional screw down versions (as shown on the right below) and add crimp terminals to all my wires, but there’s still many points of failure so I decided to try and eliminate the “umbilical” cord all together.

With everything in pieces on my work bench it became obvious I could just move the stacked board assemble up into the dome and just use the slip ring wire to connect directly into the dome.

I added a small acrylic mounting plate to the side of the domes existing mounting system.

Then the stacked board assembly just slips in and holds snug, with some velcro to make sure it doesn’t move, but still allow for easy removal and servicing.

It’s a much cleaner solution, but I’m sure it’ll evolve again as I add more stuff to the dome

Related:

• Mounting Dome Electronics
• Mist / Fire Extinguisher Test
• Dome Internal Mounting Plates