![]() |
Recommended gyros that can keep up with fast rotation?
We have one of the ADXRS450 from FIRST Choice, and it works pretty well overall. Works out of the box, drifts a little but not terribly. The issue is we'd like to code a few "automagic" buttons to go to specific angles to face certain field elements (we already have the math worked out, and rotating the robot very slowly works), but the ADXRS450 is limited to 300 degrees/second before it can't keep up with how fast you're turning. What gyros does your team have / recommend? Is this a pipe dream? We could turn slower of course, but could still get hit while turning and end up losing the gyro again... thoughts, CD?
|
Re: Recommended gyros that can keep up with fast rotation?
https://www.sparkfun.com/products/10612 is one we've used in the past with some success. We did have occasional issues with it dropping out, and i'm not sure if it was the gyro itself, or the I2C libraries/hardware on the RIO.... But, for a fast robot, this might work decently for you!
|
Re: Recommended gyros that can keep up with fast rotation?
Pigeon IMU from CTRE. 2000 degrees/s and it has integration of an accelerometer and gyro so you get a drift similar to what you'd find on other top-of-the-line IMU's like the Nav-X. Even better is that you can connect it over the can bus with 2 wires rather than mucking about with I2C or any other wiring scheme. You can also wire it in through a ribbon cable to one of your motor controllers if you are using Talon SRX's.
http://www.vexrobotics.com/pigeon-imu.html http://www.ctr-electronics.com/gadge...le-pigeon.html We used the analog kit-op-parts gyros up through 2014. In 2015 we went to the same one that 971 uses. Did it again in 2016. The Pigeon took a lot of the headache out though. |
Re: Recommended gyros that can keep up with fast rotation?
How fast does your robot rotate?
|
Re: Recommended gyros that can keep up with fast rotation?
Quote:
Really though, even if we slow it down to cap at 300 degrees / second, there's the possibility of getting pushed around a bit by someone playing defense or something and losing track of where you're facing that way. I'd like the drivers to be able to turn quickly in teleop, but still have quick and easy "go to this angle" buttons for quick alignment. |
Re: Recommended gyros that can keep up with fast rotation?
Your robot does probably turn pretty fast at full power, but you never need to turn more than 180degrees to snap to a location - can your robot really accelerate to 300 deg/s AND decellerate back to zero in 180degrees of motion?
I don't think I've ever seen a FRC robot that can do that. Do you have data that shows that you are hitting that limit? |
Re: Recommended gyros that can keep up with fast rotation?
Quote:
An IMU will help with this issue, it will take inputs from other sensors (accelerometers, other gyros, magnetometer) on the same chip, and use them to filter the gyro signal to help minimize the drift. The NAV-X, Pigeon IMU, and ADIS16448 are all used by FRC teams successfully, and are pretty well documented. I think you will have a lot more luck with one of these IMUs than you would trying to find a better quality gyro. Even with an IMU there will be some drift over the course of a match. Inertial sensors in general do much better at tracking short term relative movements than they do at tracking position or orientation over a period of time. |
Re: Recommended gyros that can keep up with fast rotation?
Quote:
That's likely enough to snap to a rough position - and if you want to use that for shooting, you'll need either vision or manual alignment anyways, so not being exactly exact isn't a problem. |
Re: Recommended gyros that can keep up with fast rotation?
Quote:
|
Re: Recommended gyros that can keep up with fast rotation?
Quote:
|
Re: Recommended gyros that can keep up with fast rotation?
Quote:
It's rare that the actual rotation rate of the robot by itself will saturate the gyro. What's more likely is that collisions will. A short period of saturation can throw a gyro off by a substantial amount. That can usually be solved by giving the drivers the ability to rezero, or by making your calculations relative to something else, like a camera angle. |
Re: Recommended gyros that can keep up with fast rotation?
Quote:
|
Re: Recommended gyros that can keep up with fast rotation?
We use a navX-MXP from Kauai Labs. It works pretty well I think, though we didn't use it last year so it hasn't gotten a whole lot of competition use.
|
Re: Recommended gyros that can keep up with fast rotation?
Quote:
It's increadibly easy to set up, small, and has accuracy beyond belief. Gyros we have used in previous years all had some slight drift and we're some what complicated to use. First use out of the box we were able to drive around blind for a little and go back to where the gyro thought was 0 to within an inch or 2. Would highly recommend the navX, only slight con is that it takes up a USB port. |
Re: Recommended gyros that can keep up with fast rotation?
Quote:
I am in no way disparaging the NavX. We've played with it and it works very well. However, I'm an engineer and I try not to make statements that product A is better than product B unless I have seen a marked difference in some measurable. |
| All times are GMT -5. The time now is 19:36. |
Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi