wakon
I was hoping someone might have an idea what else I could try ... So I got a brand new AventureBot on the weekend to start a simple robotics class at my school in the near future (and retiring my Ozobots). Watched - among others - the servo calibration video and followed the steps; easy enough. With both servos I get that one spot where no wheel spins at all, both servos keep making some buzzing sound though. Then "Move forward 1m" or a movement command in ezBlockly ... same result: the bot does not move straight, not even close to. So back to the "Continuous Rotation servo Calibration" screen on my Android tablet, tab 'D0 to 90' and 'D1 to 90' and ... Did this now at least 25+ times and the bot goes in a curve (to the right), sometimes a little less and sometimes more. I happened to reverse the inner 6 servos of a hexapod when I assembled it the first time, so I wouldn't be too surprised if messed something up again ;o).
Here is a video of the issue, can we confirm this is a servo problem?
Calibrations have been performed as per the tutorial.
@wakon
The calibration for the 360 servos sets the center 90 degree (stop) position, it doesn't have much to do with the Adventurebot moving in a straight path.
You see most 360 servos on the market spin at a different rate when moving clockwise versus counter clockwise, and this is why the Adventurebot will move in an arc. One wheel is spinning faster than the other. We have accounted for this in the ARC software.
On the side of the Movement Panel you will see 2 sliders. These sliders help you trim the speed of each wheel. Note that you will really only have to adjust one wheel to try and match the speed of the other wheel. Also note that the slower the RPM (the lower down the sliders are) the easier it will be to keep the Adventurebot moving straight.
Hope this helps!
Thank you so much for your reply Jeremie.
I think this is where it gets confusing (at least for me): <https://synthiam.com/Community/Tutorials/101>; "Continuous Rotation Servos may rotate at different speeds when moving forward. If this is the case, the servos may require calibration. This is a simple process that DJ Sures explains in the video below. ..."
What is shown in the calibration video is an adventure bot which does not move straight in the beginning, then via the potentiometers the servos are calibrated (a couple times) and voila, the bot moves pretty straight (shown via a simple Blockly command with wheel speed to equal values). Also the above quote clearly indicates that the calibration is about speed. And so I tried and tried ...
This coming school year I have a group of young students which I want to transition from the Ozobot to the EZ-Robot platform. I know that's quite a jump :o). For the first semester class they will use tablets and the Blockly language. I don't want to ride a dead horse but I am a somewhat concerned that it will be really confusing to them if they need to enter different values for left/right speed (perhaps different from bot to bot) for the robot to move straight. Especially after the fact that what they learned and experienced is (with those Ozobots) that the robot moves straight when both values are the same.
I will read more about and try out the Movement Panel - thank you for pointing me to that. So much more for me to learn
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Thanks, Wolfgang