VEXpro 2016

[JesseK]

Is the VersaPlanetary Integrated Encoder Thru Coupling the same material as the typical Versaplanetary gearset? Is there a maximum torque/power for the coupling, or is it more likely that other things will break first? This is a 'best practice' question for something like an arm or something like a 2015 tote elevator winch. Phrased via example, would the encoder be safe enough on the last stage in (e.g.) the faster stackers of 2015 or would we want to consider moving it a stage up to reduce its transmitted torque?

[Aren_Hill]

Originally Posted by JesseK

Is the VersaPlanetary Integrated Encoder Thru Coupling the same material as the typical Versaplanetary gearset? Is there a maximum torque/power for the coupling, or is it more likely that other things will break first? This is a 'best practice' question for something like an arm or something like a 2015 tote elevator winch. Phrased via example, would the encoder be safe enough on the last stage in (e.g.) the faster stackers of 2015 or would we want to consider moving it a stage up to reduce its transmitted torque?

This torque spec will be updated on the product page in the coming weeks.

-Aren

[Anthony Galea]

Does the VersaDrop only work with two 4" wheels? Or can you use a 4" wheel and a 6"?

[Richard Wallace]

Originally Posted by Grant Cox

But wait, there's more..! In addition to these new products, we are also launching some exciting new sections to our website.

Motors.VEX.com - VEX Robotics DC Motor Testing

DC motor selection is an essential part of robot and mechanism design, but the sea of specifications and options available can sometimes be confusing. To help aid budding robot designers in understanding this relationship, VEX has developed an educational guide that explains the four key characteristics of DC motors and how they can be used to select the ideal motor for your application.

Furthermore, to ensure that users have the data needed to make such an educated selection, VEX has tested seven popular motors (including the new 775pro) using industry-standard methods and published motor curves, peak power tests, and locked rotor stall tests for all to see and analyze. Head to http://motors.vex.com/ and pick your favorite motor to get started!

Best gift to the FRC community since the 2005 KoP gearbox.

100% Richard approved.

[nuclearnerd]

Originally Posted by 3175student17

Does the VersaDrop only work with two 4" wheels? Or can you use a 4" wheel and a 6"?

The total drop is only ~0.6" (only 0.2" of which is "below zero"), so I'm guessing not as designed. Instead, I'm trying to find out if the gear ratio between the two wheels can be modified significantly.

[cbale2000]

Originally Posted by Grant Cox

775pro - West Coast Products changes the rules of the game. CIM power in a 775 form-factor. You're welcome.

If I'm reading the benchmarks right and doing my math correctly... if you geared down this motor to the same RPM as a CIM, isn't it actually slightly more powerful than said CIM?

[ahartnet]

It's hard to pick a thing to be most excited about.

I'm very thankful for all the effort put into the data gathering on motors. I agree with Richard above that that might be the best gift to FRC in quite some time.

Tied with the 775Pro.

Tied with the the integrated VP encoder that can do both relative and absolute. (EDIT: See note from nuclearnerd ozrien below)

[safiq10]

This so perfect! Thank you to everyone a part of the Vex team, but one question: Will we ever get a #ballshiftsohard hoodie?

[nuclearnerd]

There's a big asterisk on the "absolute encoder" thing. It's still a relative encoder, but it includes it's own counter. It's nice not to have to implement a counter on the rio, but you would still have the problem of the zero changing every time you start up the robot. An actual absolute encoder would give the proper reading no matter how often the sensor had been turned off and moved. (see page 22 of the encoder user guide here: http://content.vexrobotics.com/vexpr...User-Guide.pdf)

I'm wondering - do the rules allow us to power the encoder from a separate 5V battery that we could leave on all the time (even when the main battery is removed)?

[Ginger Power]

It truly is a Merry Vexmas!

[ahartnet]

Originally Posted by nuclearnerd

There's a big asterisk on the "absolute encoder" thing. It's still a relative encoder, but it includes it's own counter. It's nice not to have to implement a counter on the rio, but you would still have the problem of the zero changing every time you start up the robot.

Thanks for the catch. Definitely a big asterisk that I'm glad you pointed out. Got wrapped up in too much excitement!

[nuclearnerd]

On the subject of the encoder - it looks like it needs a "diametrically polarized" magnet to spin in front of it to work. The user guide I linked has lots of tips for embedding the magnet in existing gearboxes, with the glaring exception of VEX ballshifters (which currently need encoders to have a 1/4" bushing-supported shaft).

I wonder if VEX has a solution already cooked up for ballshifters and these new encoders. If not, I wonder if it would be possible to make a replacement for the plastic encoder gear that has pockets for multiple magnets around the perimeter (or something).

[ozrien]

Originally Posted by nuclearnerd

There's a big asterisk on the "absolute encoder" thing. It's still a relative encoder, but it includes it's own counter. It's nice not to have to implement a counter on the rio, but you would still have the problem of the zero changing every time you start up the robot. An actual absolute encoder would give the proper reading no matter how often the sensor had been turned off and moved. (see page 22 of the encoder user guide here: http://content.vexrobotics.com/vexpr...User-Guide.pdf)

The sensor provides both an absolute and a relative position. The "absolute position" is an absolute 12bit encoded value that wraps every rotation. This works similarly to the MA3 absolute analog encoder which gives you an absolute voltage (0 to 3.3V) for one full rotation.

You can think of it like having an MA3 analog encoder and a relative quadrature encoder both kitted in one, which solves several challenges in closed-looping.

If you don't move the mechanism and you power cycle the sensor, the bottom 12bits of the analog position remains unchanged.

Yes both the absolute and relative positions count the wrap arounds. But this doesn't mean you lose the benefit of absolute position. If you're application does not need wrap-around counting (like a continuous swerve) its pretty easy to add in the number of whole rotations to your 12 bit target position to achieve what you want. In fact this gives you the benefit of absolute position, plus you get to decide which direction you want to servo (always clockwise, always counterclockwise, or choose the path with smallest distance.)

[Munchskull]

Originally Posted by nuclearnerd

On the subject of the encoder - it looks like it needs a "diametrically polarized" magnet to spin in front of it to work. The user guide I linked has lots of tips for embedding the magnet in existing gearboxes, with the glaring exception of VEX ballshifters (which currently need encoders to have a 1/4" bushing-supported shaft).

I wonder if VEX has a solution already cooked up for ballshifters and these new encoders. If not, I wonder if it would be possible to make a replacement for the plastic encoder gear that has pockets for multiple magnets around the perimeter (or something).

It has one.

Edit: Ops thought you were talking about the VP encoder stage.

[nuclearnerd]

Originally Posted by Munchskull

Edit: Ops thought you were talking about the VP encoder stage.

Nope, the ball shifters. Although with a little creativity, maybe the versa planetary stage could be hacked onto the ball shifter...