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Vehicle Overview and Near Destruction

April 1, 2010 Leave a comment

Just for fun

And some near destruction before proper handling of GPS popping was in place…

Apparently my code has a preconceived need to heard toward fences. Don’t ask me why….

Categories: General, Hardware, Platform, Sensors

Race Day Vehicle Ready for Duty

March 21, 2010 1 comment

Our race day vehicle is finally ready for some action.  Here are some pics:

After two weeks of battling the speed control, the Traxxas Slash is ready.  It has 4 stationary IR range finders, one scanning IR range finder, a compass, a GPS, and a wheel encoder.

Fuzzy Picture Day

March 12, 2010 Leave a comment

Managed to quickly get the new encoder installed on the Traxxas vehicle over lunch today. I only had my cell phone camera with me and the results indicate how well I can manage to take shots with it. I am completely unable to hold it still enough for close-up shots.

We managed to get the encoder mounted. Floyd constructed a few cables while I was fabricating the bracket. The GPS was also replaced on the Traxxas. Someday I’ll remember everything I need to check on a data sheet before ordering. No worries. Who cannot use a few extra bits?

Encoder is the fuzzy object left of the right wheel.

Floyd 'The Man' crimping pins.

Oops! Proto 1 takes a hit.

March 6, 2010 Leave a comment

Bang! Fencepost wins.

Sometimes things go awry even when you suspect all your bases are covered. Nothing like buggy code, open loop speed set points and a narrow region with big buildings to occlude GPS. Wack! Too bad I didn’t have video it was pretty funny to watch.

Ah well, a little broken plastic and a snapped steering linkage. Linkage is fixed and little CA will hold the broken bits for a while anyway. Good thing we have multiple platforms. At this rate, most of them will be down for repairs. The good news is I found the bug but I’m going to have to find a larger place to test to avoid future destruction.

Repair Tools


Update: All fixed up. Repairs tools included a little CA from Remote Control Hobbies – Littleton, a beverage from New Belgium Brewery and a T-REX 450 linkage pack from Ultimate Flying Objects hobby shop.

Prototype 2 up and running!

March 6, 2010 2 comments

I just finished the initial software and hardware for Prototype Number 2.  It is based on an RC Tahoe from New Bright.  This prototype contains all of the sensors we will be using in the contest and could be used as a backup is needed (albeit much slower and a much rougher ride).

We’re In!

February 26, 2010 Leave a comment

Today, I received the email from SparkFun.   Another team has dropped out so we are officially in!   Too bad for the other guys but I am happy for us.   The added pressure should ramp up the effort over the next few weeks.    So much to do, so little time….

Goodbye RC Control

On that note, work continues on the vehicle.   Today, I gutted the stock RC electronics.   Our current approach bypasses the RC receiver completely so I just removed it from the vehicle.   Traxxas did a pretty nice job of packaging the receiver and servo cable entry for water resistance/proofing.   But it had to go.

Next, an IR sensor was added to the rear of the vehicle mounted on the stock bumper.

Rear IR Sensor

Given the single sense beam, it is unlikely to be of significant help but should allow the motion planner to avoid ramming into something if the vehicle has to back up to get out of a cul de sac.   A little information is better than none at all.

I chopped up a little aluminum plate to fabricate a mount for the GPS sensor near the center of the rear axle.   Having it close to the point of rotation minimizes the need to do additional math to translate the actual position.   Simpler is better when it comes to calculations.    Once the paint is dry, I can get that installed

The encoder from US Digital should arrive on Tuesday.  By far, that will be the most complex to install and mate to the drive gear of the transmission assembly.  An accurate indication of speed is essential to being able to dead reckon between GPS updates or to handle GPS outages.    However, the steering will not have a feedback mechanism.   For now, the software will just have to trust that the set point is being achieved to determine steering angle and radius.    Not foolproof but should be sufficient.

Due to the battery compartment being only accessible from the inside of the vehicle, it makes mounting electronics difficult.  I’ll have to fab up something to allow access to the battery while still allowing the new electronics to be mounted and stable.    I should have dimensions from Floyd tomorrow when he returns from a trip so I can get that done.

In the interim, I’ll be continuing software development on our original prototype vehicle.

Prototype One

Prototype One

Floyd has already done the hard work on this vehicle but it lacks the new board plus the bulk of the sensors.   As you can see, we’re using XBee modules for remote telemetry and debugging.   Eventually, that communication will be quashed down to only a few control messages for mission execution and a remote stop signal.

Categories: General, Platform, Sensors

So what’s this all about?

February 25, 2010 Leave a comment

Team HellHound has entered the SparkFun Autonomous Vehicle Competition. Actually, we’re not officially in the contest. We’re on the alternate list and hoping some other teams will drop out or be eliminated when the video is due by April 1st.

The team is Floyd H. and me, Mark H. Combine the H’s, find a word that fits and you end up with HellHound. Worked for us. Floyd is an electronics and software guy. He already laid out a custom board for control of the vehicle and sensors interfaces. I’m primarily a software guy but am also working to get items physically mounted since I have a few more tools at my disposal. Beyond the competition, we work together and have been involved in numerous autonomous vehicle programs over the last decade. Yeah, we get paid to do it but this one is all for fun, fame, and just to hang out with the cool folks at SparkFun.

For the contest, we’re entering the ground vehicle portion of the competition. We have a couple of vehicles already computer controlled but made the decision to get one that is more capable than the ones Floyd had on hand. So I purchased a barely used Traxxas Slash. I picked it up on the 17th. Work has begun to get it equipped but I’m awaiting various parts.

Before major mods

Here’s the vehicle before invasive modifications commenced. Beyond the stock vehicle, the only thing added is the front IR sensor mount. As parts begin to arrive this week and next, changes will be pretty rapid. Currently, we’ll continue to use the stock speed controller but that may shift if speed control doesn’t have quite the fidelity we need. It might mean a brushless motor upgrade but hopefully we can avoid doing so but Floyd’s board is ready to handle it if necessary.

Front IR Sensors

Obviously, we’re adding sensing to the vehicle in addition to GPS. Considering the vehicle is going to be driving itself, knowledge of the environment is critical. The IR’s are the starting point but ultrasonic sensors are also planned. If all goes as planned, we won’t need a depth meter for the pond. Things rarely go as planned so maybe I’ll look into one.

I’ll add updated photos as the modifications progress. Once the next red box arrives from Boulder along with a couple of brown ones from US Digital, A Main Hobbies and L-Com.