dsPic-Servo

[keebler303]

I seem to remember that you need the 30 mips. If you check the source code it will specify the clock speed. If its higher than 20 mips (80 MHz) then you need the 30 mips part. If you aren't digging into the source code, I can take a look and post back. FYI this stuff is based off the same code as the OPA549 version, just modified a bit.

Matt

[Iron-Man]

Thanks for the quick reply.

[smarbaga]

the pic's oscilator can be internally multiplied.

[Iron-Man]

Which development tool is the best, PicKit2, PicKit3 or the ICD 3, for programming and debugging the dsPic30F4012 servo project?

What is the best buy/capability for the money?

Thanks

[keebler303]

I have and love the PicKit2. I have heard that the PicKit3 is twice the price for not much more capability. I have no experience nor knowledge of the ICD 3 but I know its more expensive than the PicKit2.

The PicKit 2 will program virtually every device microchip sells, including eeproms and keeloq devices. It also has some cool tools like a built in UART and logic analyzer. The UART for the dsPIC30F4012 shares the same pins as the programming pins so you can program it and then switch to the UART tool to change the parameters without having to change any wiring, etc. The logic tool allows you to debug I2C and SPI communications among other things.

I think the PicKit2 is definitely the best bang for the buck.

Matt

[Iron-Man]

Thanks Matt.

I will purchase the pickit2.

[BillTodd]

Hi Max

Have you made any progress on the tuning software?

Hello Roger, Jeff and Bill

I am currently wayting for parts to arrive to finish the driverless (10V) version.
I should be able to grab a servo and an amp to test the 10V version in the next month. Unfortunately I don't have a machine (yet) to test IRL...
First proto is DL PCB with most components in SMT (cause I love them and also cause I have a bunch of them ). I will do a full discrete version as multiple ppl are interested by the board on usinages.com
The KICAD project is GPL, if you need mods to meet your needs, you can do it. But I'll be interested by knowing what is lacking in the current board

I really want to get this English manual online but I cruelly lack of time, as i am also working on a 3 phase controller and YTT

Speaking of that, YAPSC Tuning Tool should be finished in the next few days.

the tool is Win/*nix (mac?) compatible, and makes it possible to monitor the servo's error and motor's current or to trace a response curve to ease the tuning of PID params.
But to tell the truth, even if current limiting works quite good, shunt resistor current measure is quite inaccurate for output. So current monitor will rather be usefull to know when the controller is near max current
Here's a little demo screen-shot:

I think I'll publish the project somewhere like on SourceForge -but I don't really like the commercial license of SF- or elsewhere. Anyway I'll post it here soon.
I'll also have to modify the dsPIC's code to actually send something to YTT

One last word, I designed an optoisolated USB prog key, but I'm still waiting my FTDI chip to arrive. Yes, my new comp has no external RS232 port

PS: I posted a pic here

[MaX-MoD]

Hello Bill,

well, yes and no.
There are still some bugs I failed to solve.Depending on the computer it can crash miserably after 10s of use or remain stable for a day or more...
but I didn't had time at all for it this month so I haven't done anything. I expect I'll have more time on june... not sure.

Regards,
Max

[moraru]

Hi Max,

About YAPSC, what voltage and current can feed the motor without being influence by transient voltage?

Tanks Moraru.

[Iron-Man]

I am debating on using a 28V power supply instead of a 24V supply. Has anyone tried this? Here is the link:http://www.mpja.com/prodinfo.asp?number=16754+PS


Thanks

[MaX-MoD]

seems like I forgot this thread...

Hi Max

Have you made any progress on the tuning software?

the first version (alpha 1) is finished. Have a look out here : http://www.cnczone.com/forums/showthread.php?p=589305

Hi Max,

About YAPSC, what voltage and current can feed the motor without being influence by transient voltage?

Tanks Moraru.

It depends on the power supply's capacity to quickly regulate output voltage!

Iron-man,
There should be no problem as long as you choose good MOSFETs.

[Iron-Man]

I have compiled several versions of the software. The original code Sept 2006 worked ok. I was able to get the servo motor to respond to commands in Mach2 and EMC2, with step-dir changes of Max-Mod. I then compiled version 29 January 2008, added the changes of Max-Mod for step-dir, but the servo will not respond to all command inputs, erratic. I am using a 6Mhz crystal. Also when I try to adjust the p,i,d, the servo motor runs out of control. If I set all the values back to 0,0,0, it stops. Any ideas. I believe that there may be problems in the pwm rate, etc.
What values are you all using for the p,i,d, etc. I am trying to get the original design to work before making a new design. Will send pictures later.

Thanks,

Iron-Man

[MaX-MoD]

hello,

when I try to adjust the p,i,d, the servo motor runs out of control

try swapping the A B encoder inputs or use negative values for the PID.

PID are often under 0.5. Depending on your H/W you will need P value from 0.0001 to 2 (maybe wider) so start with VERY little values.

I'll update the YAPSC:10V source archive, and then the YAPSC:V1 archive in the next few days.

ttfn!

[Iron-Man]

Thanks Max. I will try your suggestions. I used a lot of scrap parts. The encoder cable is not shielded. I will change this. I also came across this application note. It may be of some help, Brushless DC motor control using the LPC2141. Application note AN10661, software in C included.
Here is the link: http://www.nxp.com/search/?query=ARM...motor+control+

Thanks again Max.

Iron-Man

[MaX-MoD]

Okay let me know how it goes.

Concerning BLDC, I'm on it

[Iron-Man]

Max-Mod,

I failed to mention that I am using the OPA 549, although it is obvious from the pictures.
I recompiled the older code and it works, still a few problems with tuning. The power supply that I was using is an old Radio Shack supply that can barely supply 1 amp of current. I was just in a hurry to see it work. I have ordered two 12.5A 24V power supplies. With this change, shielded encoder and step-dir cables it should work a lot better. I also tried changing the motor pos-neg connections but this did not seem to make a difference. I will try changing the encoder A-B signals and see what happens. I do believe that the quadrature interface is better, but it will take a few days to fully understand the EMC2 HAL interface and programming. I will have to compare both versions of the code and double chk all references to clock speed etc. I will also purchase 14.318Mhz packaged oscillator.
I will try to post some video in a few days.

Here is a link to MSK Kennedy: http://www.mskennedy.com/
I am looking at the MSK 4251 for my final design. It is a complete H-bridge MOSFET Brushed Motor Control System. 75 volts at 10 amps. The only problem is that they are $ 175.00 for single quantities. They would almost work perfect as a direct drop in replacement for the OPA 549. I will definitely try this chip when I have all the bugs resolved in the OPA 549 version.

Thanks for the suggestions.


Iron-Man

[keebler303]

MS Kennedy caters mainly to the defense market, aero$pace, etc. Stuff that CANNOT fail. You are probably not looking for high reliability aerospace parts. For a more realistic option, take a look at an "intelligent" or "smart" power module. Most are 3 phase bridges but its fine to only use 2 for a normal H bridge. Here are a few options for relatively cheap <$50 options.

http://www.fairchildsemi.com/offers/...m/dip_spm.html
https://ec.irf.com/v6/en/US/adirect/...618+4294844516
http://pwrx.com/Result.aspx?g=112&m=65

Or if you want to get serious, check these out. How does 600V 600A sound?
http://pwrx.com/Grids.aspx?g=110&m=60

If you register there, you can get prices on most of their items on the website.

Have fun
Matt

[Iron-Man]

Thanks Matt.

I will need rad-hard parts for my armor. Just joking!!!
I will take a look at these chips.

Iron-Man

[Iron-Man]

Here are a few new photos. The main problem was with the unshielded cables on the encoder and || port interface. The X-axis is only connected at this time. The video does not do it justice. This is what my servo settings and errors are after some tuning:

BEST settings 08-02-2009
Current Settings:
servo enabled = 1
(p) = 0.010000
(i) = 0.001700
(d) = 0.000050
FF(0) = 0.000001
FF(1) = 0.000010
dead(b)and = 2.000000
(m)ax Output = 1.500000
(f)ault error = 0.000000
(x)pc cmd multiplier = 1
(t)icks per servo cycle= 10
Servo Loop Internal Calcs:
command: -22706
feedback: -22703
error: -3.000000
error_i: 0.324958
error_d: 0.000000
output: -0.032154
limit_state: 0
>
Current Settings:
servo enabled = 1
(p) = 0.014900
(i) = 0.001000
(d) = 0.000050
FF(0) = 0.000001
FF(1) = 0.000010
dead(b)and = 2.000000
(m)ax Output = 1.500000
(f)ault error = 0.000000
(x)pc cmd multiplier = 1
(t)icks per servo cycle= 10
Servo Loop Internal Calcs:
command: 7171
feedback: 7176
error: -5.000000
error_i: 30.722115
error_d: 0.000000
output: -0.006807
limit_state: 0
>

[Iron-Man]

Has anyone looked at the SA306 from Apex, 17A @ 60V?
http://www.cirrus.com/en/products/pro/detail/P1198.html
http://www.cirrus.com/en/pubs/proBul...57_PB_0908.pdf
Digi-Key has the evaluation board available for this chip.
Just wanted to make sure that I was not going down a dead end.
By the way, the errors in the previous post were for two different G code programs. The encoders are 500 ppr, ratio 2:1 on the belt reduction system. I am looking at the powder coat paint process at this time for the reduction system.

Iron-Man