Motor Controllers

[JPBlacksmiths]

So this is a question that I have had for a few years now, and never really gotten a good answer to it:

Which motor controller is the best for which situation? Meaning is there specific applications were one controller is better then the other, or is there just one motor controller which is the best, period?

This question has resurfaced for me especially with the creation of the new motor controllers such as the spark.

Thanks,
JP
Co-Captain Team 806

[DaveL]

In 2013 we liked the Talon because chips and aluminum dust kept destroying our Jags. We also like the 888 because the fan is already installed.
Going forward we are trying out the new Talons with a CAN bus.

Would like to here from others on how they connect the Talon green and yellow CAN wires together. Vex sells a nice device but it's expensive and it takes up a lot of room.

Dave

[marshall]

Originally Posted by DaveL

Would like to here from others on how they connect the Talon green and yellow CAN wires together. Vex sells a nice device but it's expensive and it takes up a lot of room.

These JST-SM style connectors are a royal pain to crimp BUT are simply amazing for connecting the talons together:



They are locking. They are cheap. And they are small. Simply awesome.

Crimping guide here explains how to crimp them (and APPs as well): https://www.ebikes.ca/documents/GrinConnectorGuide.pdf

They are just small enough that they are a royal pain to crimp though.

EDIT: We got ours from here because I know someone will ask: http://www.aliexpress.com/item/Free-...352919222.html

[SoftwareBug2.0]

Let's look at this logically:
-There's no reason for a Jaguar to be anyone's favorite
-Some people have chosen the Jaguar as their favorite

Therefore, there is there must be some fraction of people who are answering randomly. We'll assume that the people who choose randomly choose each option with equal probability.

-At this time we see 4/22 people have chosen "Jaguar" as their favorite.
-There are 5 different choices for the poll

Therefore 4/22*5 should give us the fraction of people who are choosing randomly. This comes out to approximately 90%.

QED

[GeeTwo]

Originally Posted by SoftwareBug2.0

There's no reason for a Jaguar to be anyone's favorite

Jaguar is my least favorite, but I couldn't let that challenge pass. I came up with three reasons for Jag to be someone's favorite (I left out nostalgia and thinks like being the biggest, heaviest, and having the smallest continuous current capability, and having a nonstandard PWM response):

• Supply Voltage: works down to 5.5V and up to 30V, Tied for first best at both ends with SPARK.
• Aesthetics: The jaguar case is a work of art compared to the boxes with fans (Victor 884 and 888) and the boxes without fans (the others).
• You can control a Jaguar with RS-232. I can contrive of a few applications where this would be useful, like controlling from an old PC.

Edit:

Originally Posted by MrBasse

Don't forget the fact that the flames that poured out of Jags were very entertaining for the kids!

Now I feel cheated; I've smelled and seen plenty of blue smoke, but never seen flames .

[techhelpbb]

Originally Posted by GeeTwo

• You can control a Jaguar with RS-232. I can contrive of a few applications where this would be useful, like controlling from an old PC.

PWM from parallel port and they all can be controlled by an old PC

I am waiting for the single IC speed control module. It is coming. Just a chip with bolts on the top like an IGBT and an electrically isolated metal plate on the bottom.

[GeeTwo]

Originally Posted by techhelpbb

PWM from parallel port and they all can be controlled by an old PC

I'd never heard of this, and a bit of web searches about the old centronics port leads me to think that the PC-side hardware was not made to support PWM; whether it would be possible to hack it with a tight loop that shut down the PC for any other purposes is probably hardware dependent. Has someone actually done this (using passive components, which was my meaning)?

Originally Posted by techhelpbb

I am waiting for the single IC speed control module. It is coming. Just a chip with bolts on the top like an IGBT and an electrically isolated metal plate on the bottom.

Heat dissipation is a big issue here, unless you're talking about replacing the spike rather than a speed controller. The amount of electrical isolation demanded by FIRST is also a steep challenge. I expect brush-less motors and controllers to be FRC legal before single-chip brushed motor speed controllers. I'm not holding my breath on either one.

[techhelpbb]

Originally Posted by GeeTwo

I'd never heard of this, and a bit of web searches about the old centronics port leads me to think that the PC-side hardware was not made to support PWM; whether it would be possible to hack it with a tight loop that shut down the PC for any other purposes is probably hardware dependent. Has someone actually done this (using passive components, which was my meaning)?

Ether did PWM 'bit banging' of the handshake wires on a serial port:

http://www.chiefdelphi.com/forums/sh...52&postcount=1

I used to play .mod MIDI files on a parallel port justing just a resistor ladder and a capacitor to couple still have that stuff somewhere and that was on a Intel 80386 DX 16MHz. That's complex analog audio at up to 15kHz. So yes I am sure if I sat there with some C code I could control several FRC PWM speed control on FreeDOS. I would not attempt this in on any Windows NT kernel because you need a kernel mode driver. It is likely possible on BSD/Linux.

DOS runs in real mode. You will not block the timer interrupts or other interrupts doing this. I used to run this silly trick even with EMM386 running and Windows 3.11.

HighTreason take it away old school...
https://youtu.be/4KUdBgg8Oe4

Then again....I still maintain Commodore 64 code I wrote....so I am pretty dusty.

Originally Posted by GeeTwo

Heat dissipation is a big issue here, unless you're talking about replacing the spike rather than a speed controller. The amount of electrical isolation demanded by FIRST is also a steep challenge. I expect brush-less motors and controllers to be FRC legal before single-chip brushed motor speed controllers. I'm not holding my breath on either one.

The heat dissipation of any single part in an FRC robot is no where near the heat dissipation of the big IGBT we used to charge Navy submarine batteries with this big charger we built. The base of the integrated package is metal and you torque the package to the heatsink plate with either a coupling patch or compound. One of my cohorts left a databook on a board during a test...let's just say we will not read that databook again .

The issue is merely distributing the heat away from the parts that get hot. Either make them more efficient or make the removal of heat more efficient. Same reason we could fill power supplies up with canola oil....as long as you do not let the pressure build or reach the flash point it will not conduct but it will make the heat distribute around (do not try at home kids). That silly trick allowed almost double the wattage from a power supply. By the way - TDI in Hackettstown, NJ was selling a design like this actively before AstroDyne bought them.

There was a time when people argued no FRC speed control would last without a fan either. Power MOSFETs keep getting better and better. Lower the switching losses and on state resistance enough and the heat dissipation will follow. Just please do not do it with silver in the semiconductor die (let's just say it makes the power semiconductors go bad eventually and leave it there).

[GeeTwo]

Originally Posted by techhelpbb

Ether did PWM 'bit banging' of the handshake wires on a serial port.....

I'll accept your word and Ether's.

Originally Posted by techhelpbb

The heat dissipation of any single part in an FRC robot...

I think you made my point better than I did.

[techhelpbb]

Originally Posted by GeeTwo

I think you made my point better than I did.

The actual problem is not actually the heat:
It is the whether doing that tight integration is financially workable given the market.

A massive power transistor has a much wider market than FRC and a much higher price point.

However with all the interest in drones and places like SuperDroidRobotics selling kits that are FRC size like for plows and snowblowers...the market is growing.

I suspect back in the day when audio receivers were individual power transistors many people also thought they would not be surpassed by integrated modules. Odds are if you tear down a retail home reciever you find modules in plenty of them.

[MrBasse]

Originally Posted by GeeTwo

Jaguar is my least favorite, but I couldn't let that challenge pass. I came up with three reasons for Jag to be someone's favorite (I left out nostalgia and thinks like being the biggest, heaviest, and having the smallest continuous current capability, and having a nonstandard PWM response):

• Supply Voltage: works down to 5.5V and up to 30V, Tied for first best at both ends with SPARK.
• Aesthetics: The jaguar case is a work of art compared to the boxes with fans (Victor 884 and 888) and the boxes without fans (the others).
• You can control a Jaguar with RS-232. I can contrive of a few applications where this would be useful, like controlling from an old PC.

Don't forget the fact that the flames that poured out of Jags were very entertaining for the kids!

[Alan Anderson]

Originally Posted by marshall

Crimping guide here explains how to crimp them (and APPs as well): https://www.ebikes.ca/documents/GrinConnectorGuide.pdf

One quick trick with Anderson connectors: it is
possible to remove the pin from the housing and
also to re-insert the same pin back into the
housing.
Simply take a small flathead screwdriver and use
it to lift the hook of the Anderson pin up and away
from the ledge inside the housing.
You can then pull on the wire and remove the pin
from the housing.
Because of this process you may actually end up
bending the hook upwards and it will sometimes
stay that way. In order to then reuse the pin in a
housing you will need to gently bend the hook
down until it is inline with the barrel of the
housing.

Even before I saw the last paragraph about bending the hook, I knew the instructions for removing the pin were wrong. You shouldn't pry the pin up. You just need to push down the spring (referred to in the document as the "ledge") in order to release the pin and let it be pulled out. This is true for the small Anderson connectors and for the large SB50 battery connectors.

[marshall]

Originally Posted by Alan Anderson

Even before I saw the last paragraph about bending the hook, I knew the instructions for removing the pin were wrong. You shouldn't pry the pin up. You just need to push down the spring (referred to in the document as the "ledge") in order to release the pin and let it be pulled out. This is true for the small Anderson connectors and for the large SB50 battery connectors.

Would agree with that but not my guide... I do think someone needs to create a similar guide for FRC's common connectors though.

[evanperryg]

Originally Posted by DaveL

Would like to here from others on how they connect the Talon green and yellow CAN wires together. Vex sells a nice device but it's expensive and it takes up a lot of room.

Check these out.
We used these last season. They're toolless, and we've never had a problem with them falling off or breaking. They're designed for larger wires than the CAN wires, but they still work fine. They're a little bulky, but not big enough to cause problems.

[Ari423]

My personal favorite is the Victor 888, but I chose the Spark because it does basically the same thing, costs about half, and it's still available. I would say the only case where I wouldn't use the Spark or Victor is if I wanted to do built-in PID control, where I would use the Talon SRX.

I've used Jaguars a number of times (against my will) and all I can say is NEVER AGAIN. They take up a ton of room, are prone to breaking (I had one that screeched at me), using CAN is practically impossible, and therefore it doesn't do much more than the Victor 888 or Spark.

Originally Posted by DaveL

Would like to here from others on how they connect the Talon green and yellow CAN wires together. Vex sells a nice device but it's expensive and it takes up a lot of room.

Can you not just crimp or solder them (cue debate on crimping vs soldering)?