Topic-icon NEW RELEASE: Wheelchair multi-node CANbus and analog hardware and software

8 months 2 weeks ago #29534362 by Gabriel_Isko
Thanks Lenny! This will make it much easier for me to collaborate on. Drop me a line if you ever need help supporting it and I will see what I can do.

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3 weeks 4 days ago - 3 weeks 4 days ago #29534733 by LROBBINS

Some newer Roboteq controllers now have motor current sensors. For example, the GBL2660 spec sheet says:

Measured Amps
The controller includes Amps sensors in line with the motor terminals and on the battery
ground terminals. Both Motor Amps and Battery Amps are therefore measured with precision.

The scripts I've written, both the analog and CANbus versions, do not take this into account.

There are three things to consider:

(1) With brushless motors you cannot connect one-per-motor external sensors so you MUST set "UseCurrentSensors = FALSE".

(2) The "FindEstimatedCurrents:" subroutine improves IR motor compensation for controllers that ESTIMATE motor current from battery current sensors. If your controller has built-in motor current sensors, you MUST NOT use this option either.

(3) For controllers that do MEASURE motor current, we need a third option. These need to use the Roboteq motor current values directly without any corrections. I will modify the programs so that they give this third option. But please be patient. This should not be a difficult programming task, but it will take me some time.

If you have a controller that has built-in motor current sensors, DO NOT USE MOTOR COMPENSATION until I add the third option. The easiest way to do this is to comment out the line:
GoSub MotorCompensation
in the MainLoop section of the scripts (both the analog script and the CANbus script).

Using MotorCompensation without external motor current sensors in a controller that MEASURES (rather than estimates) motor current could damage the controller and/or the motors!

PLEASE NOTE: At Gabriel Isko's request I set up a Github repository to make collaboration easier. However, no one has contributed there while many have downloaded the files from Google Drive and there has been a lot of feedback at and/or by e-mail. Having tired of trying to synchronize two separate repositories, I have deleted the one on Github. The latest files are available at: Wheelchair CANbus Controller . Any and all feedback is most welcome, and any testing observations you make are really important. You can contact me either here, or on the WheelchairDriver forums, or by e-mail.

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3 weeks 3 days ago #29534734 by LROBBINS
I have now looked at all of the current data sheets and see that many, not just "some", controllers now have internal motor current sensors. I have therefore made re-writing my code to take this into account my highest priority, and should have an update posted soon.

However, in some of the data sheets I see:

Including Amps sensors on the wires allows for fast and efficient collection of information. Battery amps can be measured in real time and which allows precise calculation of motor amps.

Can someone explain what this means? Does it mean that motor current estimates for controllers that measure "real time" battery current are accurate at less than 20% PWM? In that case, my scripts will have to treat these controllers the same way as those with internal sensors.

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