Building a second robot - electronics?

[BrendanB]

Originally Posted by Type

Sorry to change the topics but has anyone not used the D Link or Openmesh routers for their practice robots?

As long as I can remember the second robots we've had on my current and previous teams have used DLink/competition routers. We always take it with us to events so we have a spare just in case.

[Ben Martin]

It's worth it to have separate electronics for both machines, even with the expense. With FIRST Choice, it's easier to get a second copy of most components, and you can use PWM-based speed controllers across both robots to keep the costs down. If you switch anything between robots, maybe just switch the roboRIO if you can't round up the funds for a second copy.

It's far too valuable for most teams to withhold 30 lbs of whatever contacts the game piece -- this is an easy way to make sure both robots behave as close as possible and allows easier updates between competitions. We've taken this approach for the last 2 years.

[bobbysq]

Originally Posted by bdaroz

We're looking to go 2 bots this year, and we're on the fence about ordering a radio... I know FRC announced the 2016 radio would be "legal" but IIRC they didn't clarify if the 2017 Radio would be in the KoP. Would be nice to know.

Historically, all teams have recieved a router every year. I'd also check to see if you can borrow a D-Link from another nearby team if you don't get one in the KOP.

[GreyingJay]

For the purposes of driving a second robot in your home lab, it does not have to be any particular D-Link or OpenMesh router - any WiFi router that you can power from on-board the robot and that can provide IP addresses for your RoboRio and your driver station laptop will work.

Keeping with the thread topic, 2706 made it a priority early on that we were going to build two copies of our robot for drive practice (and also wiring practice, fab practice, etc.). We received one complete RoboRio control set in the rookie kit last year and one of our mentors was generous enough to buy a second whole control system to donate to the team.

Our two robots were virtually identical except one used Victor SP's and the other used Victor 888's - most sourced from vouchers and/or FIRST Choice.

Edit: here's a better photo of the twins

[Ari423]

Originally Posted by GreyingJay

Our two robots were virtually identical except one used Victor SP's and the other used Victor 888's - most sourced from vouchers and/or FIRST Choice.

Certainly infinitely better than not having two fully-functioning independent robots, but I have it on good faith that there is a noticeable difference in the response curves of the Victor 888 and Victor SP. Looking at data helpfully provided by 1718 here, the 888 does not have a linear response curve (look at Victor 888 cool, not Victor 888). I don't have good data for the Victor SP, but I would assume it has a linear response curve like the rest of the more recent motor controllers. This could likely make a difference in driver practice and autonomous programming for small movements at low voltages.

[GreyingJay]

Originally Posted by Ari423

Certainly infinitely better than not having two fully-functioning independent robots, but I have it on good faith that there is a noticeable difference in the response curves of the Victor 888 and Victor SP. Looking at data helpfully provided by 1718 here, the 888 does not have a linear response curve (look at Victor 888 cool, not Victor 888). I don't have good data for the Victor SP, but I would assume it has a linear response curve like the rest of the more recent motor controllers. This could likely make a difference in driver practice and autonomous programming for small movements at low voltages.

Yup - we noticed

In the grand scheme of things it didn't make a big difference but yes, the two robots behaved slightly differently. In this game it was largely about pedal-to-the-metal driving whether it was to fly over a defense or get to a boulder, so it didn't have a big impact on our driver training. We thought about making adjustments (squaring the inputs, etc.) but decided it didn't really matter.

[rpaulsen]

Originally Posted by trycatch

When trying to do the two robot thing, do you HAVE to have two sets of electronics? Can you use that as your weight allowance and transfer that off your second robot back to your bagged robot at competition? We have a decent influx of funding this year, and I'm stewing on trying to do the second robot thing, but it would eat up a ton of it to get two sets of just the base electronics... the roboRIO, PDP, router, breaker, VRM, etc., etc. Does anyone else swap before bag?

We tried to do the second robot thing last year, and found that using parts from the main robot and transferring them back and forth had a very steep curve of diminishing returns, and was often more trouble than it is worth. If you can afford having at least a second full control system, buy it. You always want a back up available anyway. Control system, drive train, and chassis are probably the parts you will want to just have two of if you are going to go for the 2 robot route. You will spend too much time on assembly and reassembly of these basic components that you will barely get any time to work on improving your mechanisms.

[ElectricTobi]

Hi, I am one of the Electrical lead from team 4085. I was wondering if any of you knew if there was a replacement for the talons srx's. We want to find a cheaper and/or more realiable option. I have searched the internet but could't find anything better. If you have anything, please let me know. Thanks

[bobbysq]

Originally Posted by ElectricTobi

Hi, I am one of the Electrical lead from team 4085. I was wondering if any of you knew if there was a replacement for the talons srx's. We want to find a cheaper and/or more realiable option. I have searched the internet but could't find anything better. If you have anything, please let me know. Thanks

If you want something cheaper and don't use the PID options, go for the SPARK from REV. It's only $45 and doesn't have hardwired connectors, so you don't need to worry about cutting too much of the wire down.

[Nemo]

Originally Posted by ElectricTobi

Hi, I am one of the Electrical lead from team 4085. I was wondering if any of you knew if there was a replacement for the talons srx's. We want to find a cheaper and/or more realiable option. I have searched the internet but could't find anything better. If you have anything, please let me know. Thanks

Last year's game manual includes the following in R52. Those are the only options that were available last year, and I haven't seen any news of additional controllers that will be available this year.

R52 With the exception of servos, fans, or hard drive motors permitted in R29, each actuator must be
controlled by a power regulating device. The only power regulating devices for actuators permitted
on the ROBOT include:
A. Motor Controllers
i. Jaguar Motor Controller (P/N: MDL-BDC, MDL-BDC24, and 217-3367)
ii. SD540 Motor Controller (P/N: SD540x1, SD540x2, SD540x4, SD540Bx1, SD540Bx2,
SD540Bx4)
iii. Spark Motor Controller (P/N: REV-11-1200)
iv. Talon Motor Controller (P/N: CTRE_Talon, CTRE_Talon_SR, and am-2195)
v. Talon SRX Motor Controller (P/N: 217-8080, am-2854, 14-838288), equipped with
firmware version 0.28 or newer if using via PWM. See R70 if using via CAN.
vi. Victor 884 Motor Controller (P/N: VICTOR-884-12/12)
vii. Victor 888 Motor Controller (P/N: 217-2769)
viii. Victor SP Motor Controller (P/N: 217-9090, am-2855, 14-868380)

[Type]

Originally Posted by ElectricTobi

Hi, I am one of the Electrical lead from team 4085. I was wondering if any of you knew if there was a replacement for the talons srx's. We want to find a cheaper and/or more realiable option. I have searched the internet but could't find anything better. If you have anything, please let me know. Thanks

I may be wrong but if you want a replacement meaning that it uses CAN bus, that may be the only motor controller currently that uses CAN. If you just want something cheaper, I have heard the Spark motor controllers are good, my team hasn't had the best experience with them but I know the Average Joes built an entire robot using them. They also used Talon SRs on their practice robot, which is another PWM controlled motor controller. You may want to talk to Richard Wallace to see their experience with the Sparks and Talon SRs, but there is no other CAN bus based motor controller that I know of.

EDIT: Thank you Bobby! I didn't know that, my team has always used Jaguars with PWM before we switched to Talon SRXs.

[bobbysq]

Originally Posted by Type

I may be wrong but if you want a replacement meaning that it uses CAN bus, that may be the only motor controller currently that uses CAN. If you just want something cheaper, I have heard the Spark motor controllers are good, my team hasn't had the best experience with them but I know the Average Joes built an entire robot using them. They also used Talon SRs on their practice robot, which is another PWM controlled motor controller. You may want to talk to Richard Wallace to see their experience with the Sparks and Talon SRs, but there is no other CAN bus based motor controller that I know of.

Jaguars use CAN. However, they are discontinued and to use them over CAN requires creating a special CAN cable that terminates in a phone jack.

[GeeTwo]

Originally Posted by ElectricTobi

..a replacement for the talons srx's. We want to find a .. more realiable option.

Just curious, what reliability issues have you had with the SRXs?

[Richard Wallace]

SPARK motor controllers are a very good option. Their performance and size is similar to the older Talon SR, which has proven reliability over many years of service.

The SPARK was unproven at the beginning of 2016, but our experience with it during the past 12 months of intense practice has convinced us that it can be trusted. We have bought several more since building Sparky. We used them on demonstration robots all year, and plan to use them again in 2017.

[dardeshna]

https://www.chiefdelphi.com/forums/s...hreadid=152711

Looks like they've released a new CAN controller - SD540C. Good pricing too and integrable with a network of SRXs.