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 Post subject: Tuning of PID position coefficients
PostPosted: Sun Mar 16, 2014 10:31 pm 
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Hello,
I am trying to drive 4 DC motors with metal gearbox 131:1(http://www.pololu.com/product/1447).I have one roboclaw2x5A and one Roboclaw2x15A, they are connected in packet serial.

I have been using the position command with acceleration and deceleration ramps, I got an average error of 15 pulses, but after a while positioning the DC motor emits a high-pitched and annoying.

I want to know if this problem is caused by the PID position configuration?

I attach the program that I am using.I hope somebody can help me


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 Post subject: Re: Tuning of PID position coefficients
PostPosted: Thu Apr 24, 2014 5:35 pm 
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Location: Temecula, CA
That problem was determined to be a hardware bug in the DMA handler of the xmega. We have since replaced the DMA handler with code with inline code since there was no performance cost. The DMA handler would randomly over write some registers, specifically the clock speed registers causing the processor to slow down, which caused the PWM rate to reduce enough to cause audible noise. The new firmware with inline code no longer has that problem. Most likely you will need to send the board in for the firmware update. Only 4.0.0 had this bug and had firmware update capability. If that is the case please send the board in and we'll update it. If you have the 4.0.0 firmware you can use the update function in our beta PC app: http://downloads.orionrobotics.com/down ... Motion.zip

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 Post subject: Re: Tuning of PID position coefficients
PostPosted: Tue May 06, 2014 4:02 am 
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thanks for your answer.

But, my roboclaw doesn't have a usb port, how can i connect this to the PC, I need a usb-rs232 converter...?

What is the mode of the roboclaw to connect this to the pc


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 Post subject: Re: Tuning of PID position coefficients
PostPosted: Thu May 08, 2014 3:15 am 
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Yes, you will need a USB to TTL serial cable or RS-232 to TTL adapter to connect the non-USB versions to the PC.

Mode 7(packet serial mode at 38400bps is what our PC application software uses. You can use any serial mode at any baudrate though if you are writing your own application.

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 Post subject: Re: Tuning of PID position coefficients
PostPosted: Thu Jun 05, 2014 3:30 pm 
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I have roboclaw version 3.1.5, could i use the IonMotion for tuning position PIV ?

Also, I don't know what i need to use tune position PIV, can you helpe me with some tutorial for use IonMotion aplication?.


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 Post subject: Re: Tuning of PID position coefficients
PostPosted: Fri Jun 06, 2014 3:02 am 
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I have a serious problem, I am raising a suspended load (3lb) by motors http://www.pololu.com/product/1447, controlled by roboclaw 2x15, but when moving the engine is warm, and 4 engines burn. .

Does the problem is the card or the engine?


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 Post subject: Re: Tuning of PID position coefficients
PostPosted: Fri Jun 20, 2014 5:11 pm 
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If your motors are burning up then its because your motors cant handle the load/current being drawn. A motor is rated for a specific maximum current but that isn't the maximum current it will draw. The continuous current can be 6 to 10 times less than the maximum current so you can over drive a motor and cause it to overheat which will eventually damage it beyond use.

You may need to add some kind of counter balance so your motors don't have to constantly pull large current to hold the suspended load.

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