About two weeks ago we ran into some problems with the rover. While doing some test runs on our workbench the data transmitter lost connection while at high RPM. This would cause our rover to run away and crash, if it weren't on our testbench. We originally thought that the rover was suffering from EMI and other hard to troubleshoot items. We were able to fix these problems during the three day weekend.
Our data transmitter problem was cause by a loose wire that only vibrated and lost connection at high RPMs. Here is an oscilloscope drawing of the transmitter's power supply. Note that the yellow line changes slopes. This shows that the data transmitter actually cut out and stopped pulling current from the line. After fixing this connection the data connection has again become dependable.
Next, we rewired the rover to use shielded DB-9 connections to a central box. Also, decoupling capacitors were used on the propeller protoboard.
We took the rover set up to a local gravel parking lot at the university. Ben and Ryan drove the rover from their control tent. Jordan and I manage the radio and string. Making sure the rover remained safe. We were able to drive the rover for over an hour, without any technical difficulties.
We'll keep you posted and give you more photos as we find time,
Yeah! Having access to a 3d printer has been very helpful for this project! We actually got very lucky with this because the engineering department here at the university only just got the printer this year. Its nice being an engineering student... you get access to some pretty cool stuff
So I have been very busy lately working on the video transmission system for our QuadRover. We decided to use an amateur TV(ATV) system because it will allow us to transmit video very easily over a long range! Because of the power and frequency that ATV uses we had to have a licensed amateur radio operator on our team so everyone in our group decided to go and get our amateur radio licenses. The system that I have designed uses a VideoLynx 434 transmitter and a PA5 M57716 25W amp (links below).
Once the parts arrived I had to build some small circuitry to power the transmitter and attenuate its power so that it did not overload the amp. With the help of my teammate Ryan we mounted it all in a plastic project box with a metal lid, and then we screwed down a big CPU fan to keep it all cool. I have attached some pictures of it, go check them out.
After it was all built we did some range testing with it and found that the range was quite bad, for example we were getting snowy video at just over half a mile. So I got some help from my radio expert father and he sent me a SWR meter so that we could test the efficiency of the amp. Turned out that we were pumping out 20 watts and 14watts was being reflected back! This was really bad, I figured it had to be due to a short in out antenna wire, which indeed it was a bad connection on our antenna. I fixed it and now we are able to transmit 20watts and only get back 4watts which is much better but still not perfect. If you have any suggestions on how I can improve it more please let me know.
While integrating our wheel encoders we found a problem and then made a solution. The counter is used on the propeller to keep track of how many rising edges happen per second. We then grab this data from the prop and reset the counter. It is a nice idea, but it has a flaw. The counter was triggering multiple times while the encoder signal was rising. The yellow line on the attached waveform shows the noisy signal.
We used a LM339 comparator with hysteresis to clean up the signal. The blue line is our new output of the wheel encoders. We'll let you know how this is working after our rehearsal tomorrow at 2 PM.
Our rehearsal yesterday went well. The QuadRover has no problem going across gravel, grass, steep hills, or even a volleyball court. Look at our recent video post to see it in action. I've also posted a few photos our our rehearsal. http://www.youtube.com/osurc
Our departure for Utah is approaching. We leave early Wednesday morning. Our weigh in at 10AM Thursday in Hanksville, Utah. We compete in two events on both Friday and Saturday, for four events total. We will try and post to the forum live coverage as the events complete (they have a satellite link). Our hotel is supposed to have wireless internet as well, but the photos may have to wait until we get back to OSU.
Thank you for all of your advice and support during our 14 weeks on this project!
So that time has arrived!!
The van is packed and we leave in 7 hours!
I still cant believe it ... it seems like it was just a yesterday that Parallax donated the QuadRover to us! It has been a ton of fun working with it.
BTW we should have internet access between competition events so we are going to try to update the forum with pictures, videos and results ASAP, so be sure to keep checking back with us.
Wish us luck!
Oh and John I'm sorry I do not have any pictures of inside the ATV transmitter box, but the antenna feed line is a short piece of 50ohm coax that runs from a soldered connection on the amp PCB to a PL259 connector that connects to our antenna.
So it is now the second day that we have been here in Hanksville Utah and wow its hot! We did our first competition today which was the geology task, and did quite well in our opinion but no results from the judges yet. I have a ton of cool pictures and have attached them to this post check them out their really cool! It really is like Mars out here! We are also keeping our web page up today on our progress, so you might want to check it out.
Hot!? Speaking from the great Southwest -- just wait till July and you'll wish it was June!
But, yes, large swaths of Utah and Nevada are either Martian or Lunar in appearance and desolation. Nothing like the wet Pacific Northwest.
Thanks for the photos. In one photo someone is shooting the 'bot with a high-quality DV camera -- is that one of your teammates or someone from the competition?
Best of luck. Thanks for the updates; it's been fun to watch.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔ When the going gets weird, the weird turn pro. -- HST
We were very successful at the competition, taking the lead in 3 of 4 events. Lots of pictures and video are on the way.
Zoot, to answer your question about the picture, the person shooting our rover is David Carrier from parallax. He has done a huge amount of work on the Quadrover and came out to support us, as well as get some footage of the Quadrover doing very well in the competition.
Very nice indeed !! I've seen many kinds of contests,
entered a few, and been involved in several others and
know what an accomplishment it is to even have the robot
work at the competition, and to do it all in one semester is
another big achievement.
Congratulations OSU and Parallax on the great·article about the Mars Society University Rover Challenge and the Parallax QuadRover in the November/December 2008, Robot Magazine. Great pictures and story!
OSU and Parallax are both big winners!
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Whit+
"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
Comments
Our data transmitter problem was cause by a loose wire that only vibrated and lost connection at high RPMs. Here is an oscilloscope drawing of the transmitter's power supply. Note that the yellow line changes slopes. This shows that the data transmitter actually cut out and stopped pulling current from the line. After fixing this connection the data connection has again become dependable.
Next, we rewired the rover to use shielded DB-9 connections to a central box. Also, decoupling capacitors were used on the propeller protoboard.
We took the rover set up to a local gravel parking lot at the university. Ben and Ryan drove the rover from their control tent. Jordan and I manage the radio and string. Making sure the rover remained safe. We were able to drive the rover for over an hour, without any technical difficulties.
We'll keep you posted and give you more photos as we find time,
We leave for Utah in just 8 days!
Matt Shuman
That is very sweet. Access to the 3-D printer must be *nice*.
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When the going gets weird, the weird turn pro. -- HST
1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php
Once the parts arrived I had to build some small circuitry to power the transmitter and attenuate its power so that it did not overload the amp. With the help of my teammate Ryan we mounted it all in a plastic project box with a metal lid, and then we screwed down a big CPU fan to keep it all cool. I have attached some pictures of it, go check them out.
After it was all built we did some range testing with it and found that the range was quite bad, for example we were getting snowy video at just over half a mile. So I got some help from my radio expert father and he sent me a SWR meter so that we could test the efficiency of the amp. Turned out that we were pumping out 20 watts and 14watts was being reflected back! This was really bad, I figured it had to be due to a short in out antenna wire, which indeed it was a bad connection on our antenna. I fixed it and now we are able to transmit 20watts and only get back 4watts which is much better but still not perfect. If you have any suggestions on how I can improve it more please let me know.
Amp:
http://www.hamtv.com/pdffiles/PA5-20m.pdf
Transmitter:
http://www.transmitvideo.com/model_434.html
We used a LM339 comparator with hysteresis to clean up the signal. The blue line is our new output of the wheel encoders. We'll let you know how this is working after our rehearsal tomorrow at 2 PM.
Matt
Our rehearsal yesterday went well. The QuadRover has no problem going across gravel, grass, steep hills, or even a volleyball court. Look at our recent video post to see it in action. I've also posted a few photos our our rehearsal.
http://www.youtube.com/osurc
Our departure for Utah is approaching. We leave early Wednesday morning. Our weigh in at 10AM Thursday in Hanksville, Utah. We compete in two events on both Friday and Saturday, for four events total. We will try and post to the forum live coverage as the events complete (they have a satellite link). Our hotel is supposed to have wireless internet as well, but the photos may have to wait until we get back to OSU.
Thank you for all of your advice and support during our 14 weeks on this project!
Matt Shuman
The van is packed and we leave in 7 hours!
I still cant believe it ... it seems like it was just a yesterday that Parallax donated the QuadRover to us! It has been a ton of fun working with it.
BTW we should have internet access between competition events so we are going to try to update the forum with pictures, videos and results ASAP, so be sure to keep checking back with us.
Wish us luck!
Oh and John I'm sorry I do not have any pictures of inside the ATV transmitter box, but the antenna feed line is a short piece of 50ohm coax that runs from a soldered connection on the amp PCB to a PL259 connector that connects to our antenna.
~Jordan
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When the going gets weird, the weird turn pro. -- HST
1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Whit+
"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
So it is now the second day that we have been here in Hanksville Utah and wow its hot! We did our first competition today which was the geology task, and did quite well in our opinion but no results from the judges yet. I have a ton of cool pictures and have attached them to this post check them out their really cool! It really is like Mars out here! We are also keeping our web page up today on our progress, so you might want to check it out.
http://oregonstate.edu/groups/osurc/rover/index.php?page=progress
Well we have our construction task here in an hour so wish us luck!
Hope you like the pictures.
Jordan
But, yes, large swaths of Utah and Nevada are either Martian or Lunar in appearance and desolation. Nothing like the wet Pacific Northwest.
Thanks for the photos. In one photo someone is shooting the 'bot with a high-quality DV camera -- is that one of your teammates or someone from the competition?
Best of luck. Thanks for the updates; it's been fun to watch.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When the going gets weird, the weird turn pro. -- HST
1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php
And it was actually much cooler this year than last year. I was pretty nice actually. Only got into the low 80's I think. [noparse]:)[/noparse]
We were very successful at the competition, taking the lead in 3 of 4 events. Lots of pictures and video are on the way.
Zoot, to answer your question about the picture, the person shooting our rover is David Carrier from parallax. He has done a huge amount of work on the Quadrover and came out to support us, as well as get some footage of the Quadrover doing very well in the competition.
-Ryan
Can't wait to see more pix and vids.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When the going gets weird, the weird turn pro. -- HST
1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Whit+
"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
Great job !
entered a few, and been involved in several others and
know what an accomplishment it is to even have the robot
work at the competition, and to do it all in one semester is
another big achievement.
Well done.
John-
Go check them out.
Pictures:
http://picasaweb.google.com/levyjor/URC2008/photo#s5211076041826062562
Videos:
Jordan
Post Edited (Levy (OSURC)) : 6/12/2008 9:20:09 PM GMT
OSU and Parallax are both big winners!
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Whit+
"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney