Roboteq Message Board

AX3500 position control divider

wmr — Thur, 30 Apr 2009 12:30:31 GMT

Hello,

I'm using an AX3500 to do position feedback control, using an optical encoder. However, I've run into a problem.

The optical encoders, which give out 512 pulses per revolution, are on a motor; the motor drives a gear box with a 700:1 reduction ratio. In other words, I get 358,400 pulses per revolution, or 2,800 pulses per revolution with the maximum encoder divider, 128.

So, even if I command a position move by the maximum amount, 127, it still takes 22 such commands to rotate one revolution.

Is there anything in the software I could configure to set the encoder divider higher? If it could go up from divide-by-127 to, say, divide-by-4096 it would make my life a lot easier.

Thanks.

parallax stamp and ax2550

bern — Tue, 28 Apr 2009 17:16:41 GMT

I am trying to control a robotq ax2550 with my stamp(basic stamp homework board rev b). I have the mesmic 2125 acclerometer that I want to collect data and send infor to motor controller(1x2550). basically, a segway type vehicle. can anyone help me with some sample code or direct me to a good resource.

thanks

bern

FAST linear actuators? Do they exist?

RogueWarrior — Mon, 15 Dec 2008 15:39:32 GMT

Does anyone know of a source for FAST linear actuators? Seems like everything I've seen is so painfully slow as to be unusable. Most seem to run at something like 1/4" or 1/2" per second. I'd like something that runs at 4-6 inches per second or more and with enough force to do something useful.

motors stop unexpectedly

kjy423 — Thur, 11 Dec 2008 17:51:41 GMT

Hello,

I'm using an AX1500 with US Digital encoders in mixed mode speed control. Occasionally, the motors will stop turning and not respond to the analog input. I have to power off and power back on... Actually, I have to power off, wait for the capacitors to discharge, and then power on - that's the only way I can resume control. Any ideas on what could be causing the stop?

Thanks!

AX500 - 2 Gearmotors and Linear Actuator

gregvan — Sat, 06 Dec 2008 20:23:29 GMT

Hello all...

I am trying to design a simple pan and tilt system (as small as possible) for a camera (approx. 15-20lbs) and am looking for a little advice. First, I am having a hard time trying to find the motors that would work for this (high quality), any ideas? Second, as I need to run a linear actuator (Firgelli - PQ12), is that at all possible to run through the AX500... or do I need another circuit? I am a little confused on what it means under RC inputs 2 + 1 ancillary. Sorry, I am a mech engineer who hasn't worked with circuits in about 4-5 years.

Any help is greatly appreciated...

Preview new Roboteq web site

cosma — Thur, 04 Dec 2008 18:13:23 GMT

We will soon go live with our new web site. You may preview at http://www.roboteq.com/index.php

As roboteq users, your comments and suggestions will be greatly appreciated.

Notice that the forum will be moved to our main web server. Threads have been transfered already.

Also, we will be able to grant editor access to anyone who is interested in helping build up the "project" section of the site.

My thanks to all.

AX3500 Closed loop speed control drop out

wmr — Wed, 03 Dec 2008 11:45:24 GMT

Hello,

I am using an AX3500 in closed loop speed control mode to drive two motors independently.
At maximum load (stall conditions) the battery voltage drops to around 14 V (with up to 40 A current total, below the set current limit). The controller stops working (motor power cuts suddenly) suggesting the supply voltage is below the minimum which is fine, new batteries are being investigated. However, the battery voltage immediately rises to zero load level (24 V) but the controller does not re-start. The 7-segment display is switching rapidly between all-on (with dp) and as shown below (red is on).

Powering the controller off and back on corrects the problem. I cannot find this error message in the manual. Using the Roborun software, the controller is returning the low battery voltage reading even after the voltage has returned to the high level.

Is this error message the result of going under-voltage? Should the controller not restart when the voltage returns? I have tried connecting a steady supply (24 V) to the power control connection but still have this problem. Please can anyone with experience of this problem give some advice.

Thanks

EDIT: I was looking in the wrong manual and spotted what the display means now. Any help in overriding the encoder error protection would be appreciated

AX2850 P.I.D. Control Parameters

Estilita — Tue, 02 Dec 2008 00:35:35 GMT

Hi,

I'm using the AX2850 controller in a robot and I've set the PID parameters to the maximum values. The robot has the desired behavior when its moving, but with null velocities its easy to push it if the movement is slow, it also moves if its in a ramp.

Is this a know problem? It seems like the controller can not maintain the velocities in zero if I push the robot slowly.

Thanks

brushless motors

jweber — Mon, 01 Dec 2008 16:23:46 GMT

Hello,
Can you recommend a supplier of brushless motors to work with your new controller?

analog input + max speed issues

kjy423 — Mon, 01 Dec 2008 05:10:03 GMT

Hello,

I'm using an ax1500 with encoder module and cannot seem to set a max speed. I change the time base, and the same RPM results... the only apparent control over speed I have is changing the 50% voltage setting, or changing the battery itself (not preferred).

Also, my analog input (penny and giles joystick) has only a few degrees of travel before reaching max speed... its slightly better in linear mode than exponential strong or weak, which doesn't seem to make much sense... it reads fine on the test run in Roborun, but the power swings to full in very little travel.

Thanks for any advice.

analog joystick speed control issues

kjy423 — Sun, 30 Nov 2008 04:41:49 GMT

Hello,

I've tested various settings for analog joystick channels (logarithmic, exponential, linear) and I cannot get a speed control as a function of joystick position. I'm using mixed speed mode, and all that seems to happen is that the acceleration of the motors depends on the joystick position, but they spin up to the same final speed regardless of joystick position. I seem to be limited to full speed forward, reverse, turn left or right, but no variations..

Also, (perhaps related?) sometimes the motors stop, sometimes forward becomes reverse. There's no loose connections, as when I reboot the controller, it works fine.

I'm using an AX1500 controller, with encoders, and an analog joystick (Penny & Giles). The joystick is hooked up correctly and I can see an analog variation during testing in the Roborun console (1.9d), although I am only using ~50% of full range. The encoders are also working good, as the test run in the console looks great (quadrature, 8 PPR).

Any ideas on whats up?

Thanks

beta programme AX500

starman69 — Thur, 27 Nov 2008 16:32:12 GMT

Hi looking for help with setting the voltage limits for potentiometer control!

I am about to buy an AX500 and I intend to use an Apem Series 5000 joystick with it.

I have read this:
http://www.websitetoolbox.com/tool/post/roboteq/vpost?id=2209727
...and there is mention of a beta programme that allows custom voltage limits to be set for potentiometer control!

Is it still in beta or is it normal software now?

I tried to download and open: http://www.roboteq.com/files/software/beta/roboup20u-042606-elco.zip

But no luck! (no mesh found in file...whatever that means!)

Anyway...

Before I buy the joystick and control board I want to know that everything is going to work alright!

Can anyone help me please?

Many thanks,
Starman69

How to make 2 motors run at same speed?

kiransmk — Mon, 24 Nov 2008 23:35:52 GMT

Hi Folks,

I am trying to make 2 DC motors run exactly same speed with AX3500 control board. I have been trying to do this, I have not found any success on this, So, I would appreciate, any suggestions.

Thank you.

From AX2850 to AX1500

MP — Mon, 24 Nov 2008 09:43:41 GMT

Right now, I'm using an AX2850 product. I wrote a program to communicate with it using RS232. For a new project, I would like to use a AX1500 product with the same program. I would like to know if my code will work with the second one. To write my code, I used the User manual of the AX2850. Are all the functions or at least the principal ones the same for both products?

I have an other question about the AX1500. Can I order one with a box? Can I use the same encoder I'm using with the AX2850 with the AX1500?

Thanks!

AX3500 Unexpexted movement

Pawan — Thur, 20 Nov 2008 09:26:14 GMT

Hi,

We are using a AX3500 roboteq board attached to 24 V (2 x 12V batteries) for the motors, and a separate 12V for the roboteq control. The motor controll is attached using a Spektrum AR6200 DSM2 6-channel receiver, with a DX6i transmitter. The motor control settings have been set to mixed mode and is running in open loop.

The problem is that once the roboteq board has been powered up and just sitting idle, the motors will occasionally start to turn unexpectedly. This happens with both the receiver plugged in and without anything attached to the serial port on the board.

Also whilst trying to drive the motors, the control is very jerky and doesnt tend to run very smoothly when trying to turn, and stopping causes the motors to jerk and not come to a clean stop.

Any advice pls.

Thanks, Pawan Birbal