RC Command Input Response extremely slow

General discussion of using Roboclaw motor controllers
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bensonlee
Posts: 4
Joined: Tue Sep 11, 2018 3:32 am
RC Command Input Response extremely slow

Post by bensonlee »

I have hope up a RC signal to S1 and a Motor at M1A & M1B with analogue Absolute encoder (linear potentimeter 5K with 7.5K resistor) connected.
I run the Roboclaw 2x15A with Packet Serial first and send command at the position Setting page with Control Motor1 slide bar, the feed back and control works nice. My 24VDC linear actuator response quickly with the slide bar changes. Finally stopped at the position desire. Please see attachement 1.
However, I change the control mode to RC with MCU mode ON. I restart the Roboclaw, it response to the RC signal, the it move extremely slow. But finally it stop at the position desire. Please see attachment 2

I use Slide bar to control, the end to end take around only 10 second to complete, but using RC signal the movement takes around 60seconds. Please help
Thanks.
Benson
Attachments
QP2.JPG
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QP1.JPG
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Basicmicro Support
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Joined: Thu Feb 26, 2015 9:45 pm
Re: RC Command Input Response extremely slow

Post by Basicmicro Support »

I recommend you reset to defaults and ONLY change the necessary PID and control mode settings. I see alot of different things changed from defaults(current limits set to 15amps instead of 30amp, Default accel and deccel values ar 500000 instead of 655359. I know the changes arent major but elliminate complications first so we can narrow down where the problem is.

Also remember to save your settings to the board after you setup everything.

Let me know if the results differ after you reset to defaults and reset up just the Position setting and the control mode. Please dont change any other settings you dont absolutely need to change.
bensonlee
Posts: 4
Joined: Tue Sep 11, 2018 3:32 am
Re: RC Command Input Response extremely slow

Post by bensonlee »

Thank you for your quick reply. But I try reset all to factory default. The situation is the same.
I have verified the RC was working with RoboClaw, that I unclick the "Enable Encolder 1 in RC/Analog Mode". That makes the RoboClaw working using the RC remote receiver / Pololu servo control board. But RoboClaw only working as a speed controller. With RC center was the zero speed, but I want the RC signal to drive Roboclaw work as a position control like a giant RC servo.
After I enable Encoder 1 in RC/Analog Mode, the Roboclaw start to turn the motor very very slow and stop at the position as the RC receiver signal.
Please find attached my connection drawing. I am going to use this method to create giant RC servo with extra torque in a large servo array around 24 pcs control with a servo controller board. Also in the manual, I found the mode button which using mode 1 to 4, they are all only RC/Analog controlled speed not with position mode. Looking for you reply. I am hesitate to order the remained RoboClaw if i misunderstand the function.
Thank you so much.
Attachments
connection-01.jpg
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bensonlee
Posts: 4
Joined: Tue Sep 11, 2018 3:32 am
Re: RC Command Input Response extremely slow

Post by bensonlee »

An additional information:
When I using the Packet Serial, the velocity on Position Settings page, I set the Velocity P to 50 Position P to 80, and drag the slide bar, the performance was very good and smooth. But when I change the control mode to RC with Encoder Enable. The movement was extremely slow, until I change Velocity P to 500, I can see obvious movement but it still very slow also the motor movement sounds jerky. The mentioned change was after a reset to default. Only I am not sure is the QPPS, which M1 Speed was flickering and I can get working speed at lower then 10, higher value makes the motor slower. Other values kept default value and untouched.
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Basicmicro Support
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Re: RC Command Input Response extremely slow

Post by Basicmicro Support »

1. 50 and 80 for the velocity and position P is very low. Not impossible but probably has something to do with your problem.

2. QPPS must be set correctly(with in ballpark) or Position control will not work as expected(especially when using RC signals to control position. You will need to estimate the QPPS since you cant just run the motor to determine the QPPS.

Do you have specs for the motor? Also I will need to know the range of the POT(180 degrees 270 degress, 90 degress) and the position values at the end of the ranges on the pot(high and low position values. From that information we can estimate the QPPS.

3. Make sure the Min and Max position values are set appropriately. These are not only used to limit the movement in position control mode but are also used to map the RC input signal to positions.
bensonlee
Posts: 4
Joined: Tue Sep 11, 2018 3:32 am
Re: RC Command Input Response extremely slow

Post by bensonlee »

The problem was solved by putting a much larger number QPPS (5000) and I put Position with a higher value(2000) everything works fine.

Only one question is QPPS i check as in the manual by using PWM to 100%, the reading is only around 50 and flicking in large range from 30 to 70, I'm using a absolute feed back (pot1). The POT is a industrial position linear potentiometer It is not a encoder. What is the reasonable range QPPS for a 24VDC motor at 5000RPM with no load.

Now actually everything work smooth. Can you explain more about the QPPS, i will take it into consideration in my design. Thanks.
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Basicmicro Support
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Re: RC Command Input Response extremely slow

Post by Basicmicro Support »

QPPS should be a specific value. THe maximum speed of the motor in encoder counts per second. Putting a QPPS that is not close to the actual maximum speed of the motor can cause odd behavior.

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