SD540 Motor Controller

[techhelpbb]

Originally Posted by talon540

In Talon 540's workshop, we shot a short video of our robot running with SD540's, which you can view here: http://youtu.be/9lq6U3EpyTg

There are a total of six SD540 motor controllers on this robot: four for the mecanum wheels, one for the lift, and one for the pneumatic pump.


They worked like a charm! Our team highly suggests you switch to SD540's for the 2016 season competition and onward! The manufacturer, mindsensors, has their main web page at: http://www.mindsensors.com/

Since you have these on a robot already.
Also since I will be travelling to Toronto next week till the weekend.
Additionally I will be judging NJ FLL this weekend.

Would you mind measuring the heat sink temperature during operation if you can find the necessary tools?

I'll keep working on slapping my parts together as I need to do that anyway for something else.
So far I've welded up dead axles and wired up a control system.

[philso]

Originally Posted by techhelpbb

Since you have these on a robot already.
Also since I will be travelling to Toronto next week till the weekend.
Additionally I will be judging NJ FLL this weekend.

Would you mind measuring the heat sink temperature during operation if you can find the necessary tools?

I'll keep working on slapping my parts together as I need to do that anyway for something else.
So far I've welded up dead axles and wired up a control system.

It would be good to monitor the (average) motor currents at the same time.

[techhelpbb]

Originally Posted by philso

It would be good to monitor the (average) motor currents at the same time.

While I do have the RoboRIO PDP laying around I don't have a RoboRio yet to connect to it. I haven't tried to do CAN with the PDP to the cRIO 4 slot or 8 slot that I do currently have and have been assembling.

So when I get this assembled I'll have to do that some other way unless the RoboRIO arrives by the time I get that far.

It looks vaguely like that Talon540 robot had a RoboRIO on it. So perhaps they could grab that data.

[Cory]

Originally Posted by talon540

They worked like a charm! Our team highly suggests you switch to SD540's for the 2016 season competition and onward! The manufacturer, mindsensors, has their main web page at: http://www.mindsensors.com/

Just out of curiosity, are you affiliated with mindsensors.com in any way?

If you are affiliated with mindsensors, it seems slightly disingenuous to refer to yourself/your team as a third party without a stake in the game. This is especially true when it comes to endorsement of a new product that serves a critical role and has no competition heritage.

I am in no way accusing you of not doing due diligence or appropriate testing, or questioning your results, but I think it's important for teams to know whether testimony they are basing their purchasing decisions on is coming from an end user or essentially from the inventor(s)/vendor.

[AllenGregoryIV]

Originally Posted by Cory

Just out of curiosity, are you affiliated with mindsensors.com in any way?

If you are affiliated with mindsensors, it seems slightly disingenuous to refer to yourself/your team as a third party without a stake in the game. This is especially true when it comes to endorsement of a new product that serves a critical role and has no competition heritage.

I am in no way accusing you of not doing due diligence or appropriate testing, or questioning your results, but I think it's important for teams to know whether testimony they are basing their purchasing decisions on is coming from an end user or essentially from the inventor(s)/vendor.

This controller is designed jointly with Team 540 students and manufactured in Richmond, VA with the help of local FIRST students. Source: http://www.mindsensors.com/frc/135-m...roller-for-frc

Their team helped to design them and from that seems like they help build them as well.

[techhelpbb]

Originally Posted by Cory

Just out of curiosity, are you affiliated with mindsensors.com in any way?

If you are affiliated with mindsensors, it seems slightly disingenuous to refer to yourself/your team as a third party without a stake in the game. This is especially true when it comes to endorsement of a new product that serves a critical role and has no competition heritage.

I am in no way accusing you of not doing due diligence or appropriate testing, or questioning your results, but I think it's important for teams to know whether testimony they are basing their purchasing decisions on is coming from an end user or essentially from the inventor(s)/vendor.

Just to share - I have nothing to do with MindSensors or their team.
I merely like the idea of competition for the pricing of FRC motor controls.
It's easy to go back through my post history to show that I have built other controls in the past and expressed public interest in the matter on this forum.

To be fair I also bought 2 Sparks as well.
This is not a Team 11 thing either.
It's just little old me being curious.
I have my own parts to build FRC robots so I don't have to impact Team 11 or 193 operations to do this.
I also have my own machine tools.

At the moment I am planning on doing the temperature and current measurements with an Arduino based data logger but I have more development boards than I care to discuss so I could do this with something more powerful. I will likely use a Dallas 18B20 for the temperature measurement with it installed in a steel cartridge in direct contact with the ESC heatsink and a either a TI or Maxim chip for the current measurement using a current sense resistor of a value I will disclose. It's likely the current sense resistor will be less than 1mOhm right now. I need to disclose that because it has a slight impact on the motor circuit.

[philso]

Originally Posted by techhelpbb

Just to share - I have nothing to do with MindSensors or their team.
I merely like the idea of competition for the pricing of FRC motor controls.
It's easy to go back through my post history to show that I have built other controls in the past and expressed public interest in the matter on this forum.

To be fair I also bought 2 Sparks as well.
This is not a Team 11 thing either.
It's just little old me being curious.
I have my own parts to build FRC robots so I don't have to impact Team 11 or 193 operations to do this.
I also have my own machine tools.

At the moment I am planning on doing the temperature and current measurements with an Arduino based data logger but I have more development boards than I care to discuss so I could do this with something more powerful. I will likely use a Dallas 18B20 for the temperature measurement with it installed in a steel cartridge in direct contact with the ESC heatsink and a either a TI or Maxim chip for the current measurement using a current sense resistor of a value I will disclose. It's likely the current sense resistor will be less than 1mOhm right now. I need to disclose that because it has a slight impact on the motor circuit.

Is it too much to ask if one of the Talon SRX's or Victor SP's to act as a point of reference?

As long as the temperature data is measured at the same output current, the value of the current sense resistor does not matter. The losses in the controller are related to the characteristics of the switch devices used (MOSFETS?), how they are driven by the circuitry in the controller, the switching frequency and the output current. As a user, one would only have control over the output current.

[techhelpbb]

Originally Posted by philso

Is it too much to ask if one of the Talon SRX's or Victor SP's to act as a point of reference?

As long as the temperature data is measured at the same output current, the value of the current sense resistor does not matter. The losses in the controller are related to the characteristics of the switch devices used (MOSFETS?), how they are driven by the circuitry in the controller, the switching frequency and the output current. As a user, one would only have control over the output current.

I don't have either to use as a reference currently.
AndyMark is sold out of the Victor SP.
I can get it here:
http://www.robotmarketplace.com/prod...-VICTORSP.html

At some point I have to point out that the more parts I have to accumulate on short notice the higher the unplanned cost to me of this exercise. I don't really need these chassis until well after build season outside of this. However I will entertain this because I probably will buy at least 2 of the Victor SP sooner or later. I do have the older gray Jaguar, black Jaguar, Victor 888 , Victor 884 and Talon SR (not the SRX).

Here are the constraints of doing this with a proper Arduino and the hardware I have planned:

1. The DS18B20 has variable bit resolution measurement. The more resolution the longer the readings take. I intend to run it at the fastest of 9bit resolution at 0.5C resolution. This means I need to wait likely more than 75ms to get a temperature from it. After issuing the request it can be configured to be non-blocking so I can go off and do other things then check back for the reading.

2. I will likely use either the A/D of the Arduino which for the Mega2560 is 16 channel analog muxed 10bit or something like the MCP3008/MCP3208 like that found on the Propeller ASC+ from Parallax. With the current sense resistors as I plan them this should give me something around a 0.1A resolution for the current. I would figure these are not super high-end A/D so some error is to be expected but most of the error I hope will cancel by being consistent across all measurements. The current sense resistors are high enough wattage that a complete stall shouldn't cause them to fail but likely will rail the current reading. I am going to assume we won't be trying to run the motors consistently at 95A or more.

3. The AdaFruit Data Logging shield provides a DS1307 RTC and access to SD card storage. I can also go down the route of this: https://www.parallax.com/product/27937

Since the current PDP model can only report current as fast as 25ms over the CAN bus connection to the RoboRIO, the only part of this I think is a bit slow is the DS18B20. No matter how fast my CPU/MCU that 75ms is pretty slow but thermally the heatsink mass is not so small that I think we need to be all that fast reading temperature.

4. My initial thought is to store the 2 temperatures and the 2 currents packed.
9 bits (temp) + 9 bits (temp) + 10 bits (current) + 10 bits (current) = 38 bits
Stored as 4 bytes and some bytes for any time stamps.
A trivial amount of code can unpack that and dump it into Excel.

[wilsonmw04]

Let's say someone wanted to test these new controllers. I have access to something that will read the temp. My question is how do I get the current readings off the PDB through the CAN bus? is it as simple as accessing the web based monitor?

[techhelpbb]

Originally Posted by wilsonmw04

Let's say someone wanted to test these new controllers. I have access to something that will read the temp. My question is how do I get the current readings off the PDB through the CAN bus? is it as simple as accessing the web based monitor?

Can you read the heatsink temperature(s) with the RoboRIO with whatever you have (does it have an analog, I2C, SPI output)? If you can you should be able to get the current and the temperature together and log or display it with some coding.

If I had the RoboRIO laying around on a robot with the necessary accessory this would be a fine way to do it.

In Java:
http://wpilib.screenstepslive.com/s/...ribution-panel

In C++:
http://wpilib.screenstepslive.com/s/...ribution-panel

In LabView (see GetPDPCurrents):
http://www.fightingpi.org/Resources/.../LabVIEW.shtml

For the cRIO in general there's some information on National's site about using the DS18B20.
For I2C temperature measurement one might use this: https://www.sparkfun.com/products/11931
Never tested any of this temperature reading stuff on the RoboRIO.

This will help with writing the data you collect out:
http://www.chiefdelphi.com/forums/sh....php?p=1437880

If you do manage to test this please do post the results because the scope of work for me to do: it seems to be growing .

[philso]

Originally Posted by techhelpbb

I don't have either to use as a reference currently.
...

I do have the older gray Jaguar, black Jaguar, Victor 888 , Victor 884 and Talon SR (not the SRX).

A Talon SR would be a good reference too.

[techhelpbb]

Originally Posted by philso

A Talon SR would be a good reference too.

LOL if you had written that about an hour ago
2 Victor SP are on the way to me.

[philso]

Originally Posted by techhelpbb

LOL if you had written that about an hour ago
2 Victor SP are on the way to me.

With all the facilities and parts you have mentioned in your previous posts, I go a serious case of "shop envy". It is now a bit worse

[techhelpbb]

Originally Posted by philso

With all the facilities and parts you have mentioned in your previous posts, I go a serious case of "shop envy". It is now a bit worse

At the rate of accumulation I have 8 Lowes 12 gallon plastic totes filled to the very top in storage. It got to the point I couldn't remember my inventory so I have an inventory spreadsheet. It's not quite as expensive as one might imagine: as I have been accumulating parts for years and only accelerated in recent months. I cleaned out quite a few MicroCenters nationwide after giving everyone several months and a ChiefDelphi thread to beat me to it. MicroCenter discounted most of the AndyMark parts down to 75% off. I routinely hit AndyMark's Tuesday deals. I'm also often the reason a few of you aren't winning your eBay auctions the last few months and at least in a recent case that means I sponsored a team or so indirectly.

It's not just for me, at least I hope not, I am working towards setting up a MakerSpace with FRC resources available. Hence my growing portable MaxNC toolset with the T2 lathe and 10 mill. I am also doing modifications and repairs on them such that if someone breaks them I can fix them cheap and easy.

This is why I was going to build some robots anyway. I will be using smaller final robot dimensions when I get there. I want mine to fit in the largest TSA approved hardshell suit cases so I can take the robots and my portable CNC tools safely more places. This is more an educational exercise out of my pocket than a competitive exercise. It's just not practical for the most dedicated students to learn CNC and programming in 6-10 weeks and the high cost of CNC entry is daunting just to get to a point you realize you don't know G-Code from Rhino VBA . (For anyone that points out the MaxNC machines are glorified Sherline/Taig machines: cutting wax for someone that knows no better is just as good on 1/3HP as it is on 10HP. Sure the feeds change and that just goes to reinforce the critical nature of that change.)

If this doesn't work out I will have to open a new web based FRC retailer

[talon540]

If you are wondering how the SD540's heat up over time, mindsensors and Talon 540 performed a few tests on one of our old robots.

http://www.team540.com/sd540/