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Actuator moving to max in standby
#1
After creating a working workbench setup of the pypilot autopilot. I created a integrated working autopilot for my boat. My first use was sailing downwind in a gentle 10-12kts wind. And it was performing nicely. But at some point it started to drift from the set course. As indicated in a previous topic, this was due to a low P-value. Later I incrementally increased this from 0.0030 to 0.0060. With this value, the course steered comes back to within 1° a 2° of the set course. This second test with this increased P-value was done on engine power with a flat sea. So it still could be that I should change other values too, to balance the increased P-value.

I do have one rather strange malfunction after about 4-5 hours of use. When placing the autopilot in standby, it immediately starts to extend the actuator to maximum. Where it stops the power due to the integrated limit switches in the actuator. In previous operations, this didn't happen. When I want to engage the autopilot again (by placing the actuator on the tiller), I have to decrease the length of the actuator to fit on the tiller, put pypilot into "auto" and quickly place this on the tiller. I am not sure how this could occur all of a sudden. One thing that comes into mind, is that I didn't ground all the unused analog inputs. Could that be the source of the problem?

Some basic information about my setup is:
Computer:
RPI-W Zero,with 9250, nokia display and 6 buttons
MotorController:
Arduino Nano, VNH2SP30 without rudder, voltage, limit sensors connected

And some photo's from my setup:
   
   

regards:
Wouter
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#2
I suspect it is something in the pwm_mode == 2 as you are using a vnh2sp30 homemade controller correct?. It must disengage rather than make a command.

See if you can repeat this issue multiple times an it should be possible to track down.
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#3
Indeed, I am using a home made version of your design with the vnh2sp30 motor driver. The strange thing is that it worked flawlessly, also putting the drive in standby didn't gave any troubles. And all of a sudden, I cannot put the drive in standby without taking of the drive quickly (because of the sudden extending of the actuator).

Coming weekend I'll try to do some tests. I've just winterized the engine, so the testing will be dock-trails. I'll post the result this Saturday.

One question though. As I mentioned in my opening post, I didn't ground any of the not used inputs. Could this result in any of this? That at some point, stray currents could result in sudden movement of the actuator?
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#4
I found the RasPi is sensitive to power supply issues and noise.
So I use a single 5V power supply soldered directly to the GPIO pins with a 100n cap on the supply lines
Even added a ferrite bead on the supply cable
Shielded and grounded the cable from the PI to the motor controller.
I also ensured the IMU HAT is solidly mounted on the PI header.

Not sure if this helps, but it does eliminate a potential issue.
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#5
the actuator should not move from stray inputs.

The only thing I can think of is probably bug in motor.ino specific to pwm mode 2. It is something that is possible to fix if you can reliably reproduce it.

I have another bug in raspberry pi which took me on average 8 hours to reproduce. After several weeks dealing with this the problem seems to be outside of pypilot itself and something to do with power management. I'm not really sure since my pi will not boot with my hdmi screen connected, it must boot without, and then I have to unplug and plug the screen anytime it goes to standby to get the display back, so I managed to reproduce the same "bug" with a 3 line python script so clearly not a pypilot bug, but I am still confused by it and trying to determine the root cause...
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