pathfinder tag:roderickmann.org,2008:/pathfinder/4 2006-06-01T00:16:43Z EE192 Project Log, Spring 2006, Team 9 (John Breneman, Bobby Gregg, Roderick Mann) rmann (AT) latencyzero (DOT) com Movable Type 3.2 NatCar 2006 First Run tag:roderickmann.org,2006:/pathfinder//4.195 2006-05-28T22:06:21Z 2006-06-01T00:16:43Z Here's a crude video of our first run. I don't have video of the second (winning) run; we'll have to get that from the school. This one resulted in a time (also fast enough to have won) of a little... Rick http://roderickmann.org/ Here's a crude video of our first run. I don't have video of the second (winning) run; we'll have to get that from the school. This one resulted in a time (also fast enough to have won) of a little over 36 and a half seconds. The winning run video will come later.

This video requires QuickTime 7 to play.

NatcarMovie.png

]]> We Did It! We Took 1st Place in NatCar 2006 tag:roderickmann.org,2006:/pathfinder//4.194 2006-05-27T02:42:28Z 2006-06-01T00:13:19Z We ran our best time at a PWM setting of 75, resulting in 34.072 s, for a computed average speed of 3.01 m/s (9.86 ft/s), a new competition record (previously set in 2000 by UCB team 4 at 9.82 ft/s).... Rick http://roderickmann.org/ We ran our best time at a PWM setting of 75, resulting in 34.072 s, for a computed average speed of 3.01 m/s (9.86 ft/s), a new competition record (previously set in 2000 by UCB team 4 at 9.82 ft/s).

Cal also took the number 2 and 3 places.

Official NatCar stats:

http://www.ece.ucdavis.edu/natcar/Race_Results.html

]]> NatCar is Coming Up tag:roderickmann.org,2006:/pathfinder//4.193 2006-05-22T20:45:09Z 2006-05-22T20:51:24Z John and I managed to track down a bizarre error. We discovered that from revision 68 to 69, a change was introduced in the port configuration that revealed a manufacturing defect in the controller board PCB. One of PORTA's pins... Rick http://roderickmann.org/ John and I managed to track down a bizarre error. We discovered that from revision 68 to 69, a change was introduced in the port configuration that revealed a manufacturing defect in the controller board PCB. One of PORTA's pins was shorted to one of the PWM output pins. Up until r69, PORTA had been configured as all-inputs, but when the software was changed to set PORTA to all-outputs, it was preventing the PWM channel from reaching 5 V (I'm glad we didn't damage anything).

This seemed to cause the motor to run rough up to a speed of about 4 increments on the joystick (PWM duty cycle value 20).

Anyway, we worked around that by not setting that pin to be an output, and then went on to find the actual code that had been used for Round 2—it was on my older PowerBook, and had not been checked in (bad Rick!), so it took a bit of finagling to get Subversion to accept it.

The next steps are to add in the derivative term, speed up the control loop, and tweak on the courtyard track in Cory. I also want to get our ZigBee link working, and I need build a new sensor board (I hate perfboard!). NatCar is on Friday, and we have a lot to do to be competitive.

Here's hoping the card keys still work…

]]> We made c|net! tag:roderickmann.org,2006:/pathfinder//4.183 2006-04-26T06:25:53Z 2008-04-08T06:49:05Z Thanks to John for pointing this out. c|net came and covered the Maker Faire, and we've got a few seconds of our car running the laps. The video timer counts down, but check time 2:25 (click the image for the... Rick http://roderickmann.org/ Thanks to John for pointing this out. c|net came and covered the Maker Faire, and we've got a few seconds of our car running the laps. The video timer counts down, but check time 2:25 (click the image for the video page):

CNetCoverage.png

]]> Pizza! tag:roderickmann.org,2006:/pathfinder//4.182 2006-04-25T08:22:41Z 2006-04-27T09:21:14Z Our professor (Ron Fearing) did a very nice thing for us tonight after Round 2: he took us all out for pizza. Fairly rare (for a prof. to do so), and very nice. Thank you, professor!... Rick http://roderickmann.org/ Our professor (Ron Fearing) did a very nice thing for us tonight after Round 2: he took us all out for pizza. Fairly rare (for a prof. to do so), and very nice. Thank you, professor!

]]> Round 2...Second Place :-( tag:roderickmann.org,2006:/pathfinder//4.181 2006-04-25T05:46:32Z 2006-04-25T05:58:05Z Sigh. We missed first place by about 0.6 seconds. We had a lap time of 43.9x seconds, the other guys were 43.3x (something like that). Starting at around 1pm I re-tuned the sensor board, and re-wrote the linearization code to... Rick http://roderickmann.org/ Sigh. We missed first place by about 0.6 seconds. We had a lap time of 43.9x seconds, the other guys were 43.3x (something like that).

Starting at around 1pm I re-tuned the sensor board, and re-wrote the linearization code to compute 1-over-right minus 1-over-left, and just tweaked the values 'till the car did something right. There was still no time to add the derivative term.

We might've been able to run the last lap a little faster, but we just ran out of time to do so.

So, next steps are: 1) catch up in all my other classes (HA!), 2) prepare for Natcar. Sigh.

]]> Mythbusters! tag:roderickmann.org,2006:/pathfinder//4.178 2006-04-23T21:15:00Z 2006-04-27T09:32:09Z Awesome. Highlight of our day. L-R: Quan Gan, John Breneman, Grant Imahara, Jamie Hyneman, Adam Savage, cute kid (Adam's son?), Rick Mann, Charlie Chiau, Tracy Wang We asked them to bless our car, so Jamie rubbed his head on it... Rick http://roderickmann.org/ Awesome. Highlight of our day.

Mythbusters
L-R: Quan Gan, John Breneman, Grant Imahara, Jamie Hyneman, Adam Savage, cute kid (Adam's son?), Rick Mann, Charlie Chiau, Tracy Wang

We asked them to bless our car, so Jamie rubbed his head on it and they all signed the MCU board. We're sure to win Natcar now:

Autograph

Many thanks to Bobby for manning the fort while we went to play!

]]> Maker Faire This Weekend tag:roderickmann.org,2006:/pathfinder//4.177 2006-04-23T04:06:57Z 2006-04-23T21:07:55Z Charlie and I (almost) finished setting up the track a while ago. I'll post pictures of the space, and tomorrow a better entry showing the booth.... Rick http://roderickmann.org/ Charlie and I (almost) finished setting up the track a while ago. I'll post pictures of the space, and tomorrow a better entry showing the booth.

]]> Telemetry and BlueSMiRF Details tag:roderickmann.org,2006:/pathfinder//4.176 2006-04-17T06:07:18Z 2006-04-17T06:47:06Z Okay, I've been beating my head against the BlueRadios wall all weekend, and I think I finally came up with enough of a solution. Sending Telemetry First off, I've written a buffered, interrupt-driven packet transmit API. One packet can be... Rick http://roderickmann.org/ Okay, I've been beating my head against the BlueRadios wall all weekend, and I think I finally came up with enough of a solution.

Sending Telemetry

First off, I've written a buffered, interrupt-driven packet transmit API. One packet can be assembled and queued while another is being transmitted. The calling context only blocks for the time it takes to assemble the packet (and possibly copy it to the send buffer, if no packet is currently being transmitted).

It does not yet respect the RTS signal, because I don't have a good way of restarting transmission when RTS comes back. Ideally, RTS would generate an interrupt, but RTS and CTS are connected to port G, and on the ATmega128 there's no interrupt-on-change on Port G (oh, how I long for the ATmega1281…).

The alternative is to set a timer to go off and try again in some short period of time, but that solution is inelegant. I've opted to ignore the problem for now. The firmware doesn't send data until after a connection is established and data is requested, and it doesn't send it so fast that the link gets saturated. Note that as the range increases, so do transmission errors (we were unable to run in the courtyard at 76,800 bps, had to drop to something terribly slow to get it to work), and the risk of saturation is much higher. I've ordered the new BlueSMiRF module which can accommodate a better antenna, hopefully that will help guard against range issues.

BlueSMiRF Send While Receive

I was having a very serious problem sending data to the car while it was sending back telemetry. I think I've managed to solve it, thanks to some hints dropped on the BlueSMiRF forums. Basically, the BlueRadios part is overwhelmed trying to parse the input stream, and can't send data in both directions when it's busy. Switching it into "fast data mode" stops the parser, allowing overall faster transmission speeds, and seems to allow data to go both ways. The drawback is that settings cannot be changed in this mode, which means the mode cannot be exited if permanently set.

So, the Java app will do this on connect: Send +++\ratmf\r. This will put it into fast data mode until power is lost. It's the best we can do.

]]> Step Response Checkpoint Prep tag:roderickmann.org,2006:/pathfinder//4.175 2006-04-14T07:51:44Z 2006-04-14T08:04:51Z In preparation for tomorrow's (today's?) checkpoint, we gathered some data from the car. The graph below shows the car's computed error and velocity over a period of about 3 seconds. This graph shows the car's computed position error against the... Rick http://roderickmann.org/ In preparation for tomorrow's (today's?) checkpoint, we gathered some data from the car. The graph below shows the car's computed error and velocity over a period of about 3 seconds.

ThStepResponse.png

This graph shows the car's computed position error against the actual error (distance from the track).

ThComputedVsActual.png

]]> Gain Constant Kp tag:roderickmann.org,2006:/pathfinder//4.174 2006-04-14T05:44:08Z 2006-04-14T05:46:33Z Given a Kp=2 (with kSteerScale=256) in our C code units, the real-world value is Kp = (7*pi/180)/0.03 = 4.07 rad/meter. That's a map of about times-two in the linear region.... Bobby Given a Kp=2 (with kSteerScale=256) in our C code units, the real-world value is Kp = (7*pi/180)/0.03 = 4.07 rad/meter. That's a map of about times-two in the linear region.

]]> Digital Filtering tag:roderickmann.org,2006:/pathfinder//4.172 2006-04-11T05:03:53Z 2006-04-11T17:10:10Z I wrote a simple 8-tap moving average, and some code to spit out values for the left-minus-right error, filtered error, and steering command. The steering command range is very small, so it doesn't show up like much on these graphs.... Rick http://roderickmann.org/ I wrote a simple 8-tap moving average, and some code to spit out values for the left-minus-right error, filtered error, and steering command. The steering command range is very small, so it doesn't show up like much on these graphs. The graphs are over time, with each data point coming in at 200 Hz, or every 0.005 s.

Click each graph for a larger version.

This graph shows a section from 1000 to 1500.

ThFilterGraph.png

This graph shows the filter startup (you can see the initial value is zero, and it ramps up).

ThFilterStartupGraph.png

]]> Monday: Round 1 Winners! tag:roderickmann.org,2006:/pathfinder//4.171 2006-04-11T05:01:46Z 2006-04-11T05:03:33Z Today was round 1 of class competition. We had the fastest lap time of 33.99 seconds, using proportional-only control, a speed of 6, and a Kp divider of 135. These numbers don't mean much, I know, but in the cp20060407... Rick http://roderickmann.org/ Today was round 1 of class competition. We had the fastest lap time of 33.99 seconds, using proportional-only control, a speed of 6, and a Kp divider of 135. These numbers don't mean much, I know, but in the cp20060407 branch, they make sense.

Video to follow later.

]]> Sensor Board Pot tag:roderickmann.org,2006:/pathfinder//4.168 2006-04-04T02:32:45Z 2006-04-04T02:33:19Z Just noting a part number for potentiometers on the sensor board. DigiKey: 3223W-1-204ECT-ND.... Rick http://roderickmann.org/ Just noting a part number for potentiometers on the sensor board. DigiKey: 3223W-1-204ECT-ND.

]]> Non-linear Control Simulations tag:roderickmann.org,2006:/pathfinder//4.166 2006-03-19T23:54:52Z 2006-03-19T23:58:03Z After a day of playing with MATLAB's scoping characteristics, I was able to implement the PD controller in code (part 1a and 1b of the assignment). You can see that I was able to calculate an optimal pair of Kp/Kd... Bobby After a day of playing with MATLAB's scoping characteristics, I was able to implement the PD controller in code (part 1a and 1b of the assignment). You can see that I was able to calculate an optimal pair of Kp/Kd coefficients (10/2) using my nifty Mathematica eigenvalue analysis. Here is the code, and here are the plots for Proportional and Proportional-Deriv control:

1a(Pcontrol).png

1b(PDcontrol).png

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