pdmarsh

Thank you, Heppu! I happen to have a 3D printer and even printed a battery cover for an old NXT a while ago. With your instructions I think I can do this. Paul

Thank you 2GodBDGlory. I had a feeling that might be the solution. I did think about a custom adapter, but I don't know much about electronics and how the battery holders are wired internally, i.e. in series or parallel, also amperage and all of that. I know the terms, but not the practice. Paul

Is it possible to run the Mindstorms EV3 with an AC power adapter? I don't have a rechargeable battery for it, but could that be used and simply kept on charge while powering the device? My current application using the EV3 just isn't practical with battery power alone. Thanks, Paul

It looks like a lot of folks have had trouble finding details behind the Lego EV3 Stair Climber program as I did. The pdf provided by Lego shows a "My Block" without any information as to what it contains. Also, the current version of the EV3 Classroom app available for download does not have any of the expansion set models in it, and I can't see any way to update it to get those models. Fortunately, I found the following example of a Pybrick program for the Stair Climber. If nothing else, this provides the logic behind the entire program: Pybricks Stair Climber Program Finally, here is a link to an image of the EV3 program I made using the above as a guide. You might have to tweak some of the settings, but this works for me. EV3 Stair Climber Program I hope this helps. Thanks, Paul P.S.--Video of stair climber robot in action: Video

It looks like a lot of folks have had trouble finding details behind the Lego EV3 Stair Climber program as I did. The pdf provided by Lego shows a "My Block" without any information as to what it contains. Also, the current version of the EV3 Classroom app available for download does not have any of the expansion set models in it, and I can't see any way to update it to get those models. Fortunately, I found the following example of a Pybricks program for the Stair Climber. If nothing else, this provides the logic behind the entire program: Pybricks Stair Climber Program Finally, here is a link to an image of the EV3 program I made using the above as a guide. You might have to tweak some of the settings, but this works for me. EV3 Stair Climber Program I hope this helps. Thanks, Paul P.S.--Video of stair climber robot in action: Video

That's it. I did manage to find, but only after I made my post. Thanks for the reply, though. I appreciate it. Paul

Some time ago I stumbled upon a website that would give a list of possible projects based on the Lego kits you have. I don't recall if it was Mindstorms-only or if you could enter all kit numbers. My interest is in Mindstorms. I can't find this site again. If it rings a bell with anyone here, I would greatly appreciate the link. Thanks, Paul Naturally, after I made this post and continued the search on my own, I found the site. It is www.rebrickable.com for anyone else that might be looking.

On a whim, I decided to try GyroBoy on carpet instead of a smooth floor to see if the added resistance helped with balance--it did. So, at least I knew it could work. I started playing with some of the variables that affect power, or both speed and drive in the parlance of the program, and found that changing a multiplicand of speed from 0.08 to 0.11 in the EQ block allowed the robot to balance on a smooth surface without falling down. It's the "a" variable in the attached image. I'm making progress...

Hi David. Thanks for the response. No physical issues that I can see. I removed the additional sensor I added between the motors for the line-following exercise noted in my post. Still no-go. I'm hoping someone will point out what parameters can be adjusted to tune performance. Paul

If you are familiar with the GyroBoy project, you might be aware that there are, at least, three versions of pre-written programs for the robot. At first I could only find a pdf file showing the Lego-written program for the Mindstorms EV3 Home Edition software. You have to write the program yourself using the pdf as a guide, but not all detail is shown and you have to figure out some things on your own--even some of the initial variable values are not clearly shown. More on this in a minute. A second Lego-written version can be found on the EV3 Classroom app and is ready for download. Finally, there is the version found on the Robotsquare.com web site. Of the three, I have only had success with the latter version. I tried to write the Home Edition version from the pdf file, but it did not work at all at first. The robot wouldn't balance at all, let alone move and balance at the same time. I tried using the EV3 Classroom app version as a guide to fix the Home Edition file, but, while the programs appear to function the same, the individual program steps are fairly different. After a great deal of searching, I found an "official" pre-written version of the Home Edition file and had a bit more luck with it, although I am still having problems. Finally, I ran the EV3 Classroom version and can't get it to work either, although its initial behavior is quite similar to what I see with the Home Edition program I downloaded as noted above. Immediately after startup with these two versions, the robot will balance a bit but quickly gets into an over-control state and falls. I played around with some of the gyro variable settings and had marginal success, i.e. the robot will balance but is wobbly and slowly goes in a tight circle. Any attempt to use the color-controlled actions will cause it to fall. Unlike tuning a PID loop, I have no idea what settings to tweak to get these programs and the robot to work as they should. As mentioned, I had a good experience with the Robotsquare file, but I'd like to get the Lego programs to work as well. I would appreciate any guidance anyone can provide on what variables or settings to tweak to properly tune the robot. As an aside, I added line-following capability to the Robotsquare version with success. However, it moves painfully slow. The balance loop, I think, inhibits attempts to speed up the forward motion. A better programmer could probably eke out better performance. Here's a video of the line-follow version: Line Following GyroBoy Thanks, Paul

The Dexter Industries dGPS sensor manual has a reference to use I2C commands to turn on and turn off extended firmware functions that provide HDOP, altitude and number-of-satellites data. The manual also states that these extended functions can slow down dGPS processing. I am seeing some long delays in updating distance-to-waypoint data from the navigation block used with the sensor. I would like to turn off the extended firmware functions temporarily to see if the distance data gets updated quicker. However, I don’t know how to send I2C commands to the dGPS via the NXT-G configuration software, or if it’s even possible. I would appreciate any guidance I can get on how to send I2C register change commands to the dGPS sensor. Thanks, Paul

Hi David, Thanks for the response. A problem with feedback does appear to be the issue. I'll be able to deal with this through programming, but I was curious about it nonetheless. Thanks again, Paul

One of my NXT servos is exhibiting some odd behavior. I had to replace a servo for a different reason and this might be the replacement, but I'm not entirely sure as I didn't mark it as such. In any case, I'm curious if anyone else has seen this and knows the cause. With two servos that act as expected, I can place a single Move block in the program and use any of the duration settings and both servos will run and stop when programmed or run continuously if "Unlimited" is selected. However, when one servo is replaced with the misbehaving one, regardless of the duration setting, the latter servo will run continuously and the good servo will twitch as if it's about to run, but stops immediately. I have to end the program to get the "bad" servo to stop. If I place the Move block inside a Loop set to "Forever," the above behavior will be identical except for one scenario. If I set the Move block duration to "Unlimited," both servos will run and can be controlled by the Loop's "Control" setting, i.e. they will either run continuously or run and stop as set by the loop control setting. Simply using individual "Motor" blocks to control the servos does not solve the problem. There are good and bad programming scenarios with those as well with regard to the bad servo. The best guess I can come up with is that the bad servo is either not sending or not receiving a feedback signal, maybe both. I did wonder, though, if these servos have any firmware in them that might behave differently depending on when they were made. This isn't a fatal flaw as I can use the servo, but I am curious what might be going on. Thanks, Paul