Originally Posted by otherguy (Post 1310603)

I think $70 shipped is a fair price. We would be in for one at that cost.
That said, unless we NEED an IMU to play this years game (unlikely), it's unlikely this board would be put to use on the 2014 robot. It will likely be put off until the off-season for further investigation.



I realize the surface mount components won't make sense for a lot of teams. My main reason for asking was simply to bring the price down a bit. I believe our team could populate this board in house. I've worked surface mount components by hand numerous times, but would likely temporarily set up a reflow oven/hot plate for this one to make things a little easier on us. I wouldn't recommend redesigning the board this close to the season starting, especially if you plan on trying to sell these in support of the 2014 season.

Originally Posted by slibert (Post 1310106)

Team 2465 (Kauaibots) has completed initial development of the Nav6 Open source IMU. This project includes:

- Open source hardware (Eagle PCB file, Bill of Materials)
- Open source hardware (Arduino-compatible source code)
- Software to integrate the IMU into a C++-based CRio robot project

The "nav6" inertial measurement unit (IMU) was developed to provide sophisticated inertial navigation capabilities easily available to student robotics teams, including the FIRST Robotics Challenge (FRC). This low-cost circuit board enables a 4-wheel omni-directional drive robot to be driven in "field-oriented" drive mode by accurately measuring the robots "pose" - the amount of tip, tilt and rotation - relative to the field. Additionally, the nav6 can be used to implement robot balancing algorithms.

The nav6 features the powerful Invensense MPU-6050 IC which includes a 3-axis accelerometer, a 3-axis gyroscope and an on-chip digital motion processor. The nav6 employs sophisticated motion processing algorithms provided by the "Digital Motion Processor" (DMP) included with the MPU-6050. The result: highly accurate tip/tilt, and accurate yaw that exhibits minimal drift of approximately 1 degree per minute. The sensor provides a 200Hz update rate, excellent for use in robotic systems.

The nav6 also includes a Honeywell HMC5883L 3-axis magnetometer. Although the magnetometer compass readings are unreliable when robot motors are energized, it is useful for establishing absolute orientation at the beginning of a competition. Combined with the nav6 "pose" and this initial orientation, a robot's absolute orientation throughout a competition match can be maintained.

The nav6 has been designed specifically to enable easy integration into a FRC robotics control system: it's power connection connects directly to an unregulated 12V output on the Power Distribution Board and it's data connection connects directly to the cRio serial port. Additionally, source code for easy integration into the FRC cRio controller is also provided.

As an added bonus, the nav6 is Arduino-compatible, and can be re-programmed by anyone via the free Arduino Integrated Development Environment (IDE).

Links to the open source hardware/software project, and the CRio software to interface with this IMU, are at: https://code.google.com/p/nav6/

Advanced soldering skills are required if you want to build it, but I'd be happy to indicate where you can get the board fabricated and provide some guidance on how assemble it with a minimum of tools. I'm also open to having some assembled for a low cost if there's enough interest.

As an alternative, it should also be possible to adapt the firmware to run on open-source boards w/the MPU-6050 and the HMC5883L, these can be found at Sparkfun. The ArduIMU +V3 (https://www.sparkfun.com/products/11055) is $79.95 and features almost identical ICs, however it doesn't have the on-board RS-232 IC/connector so you'd need to take care of that detail.

If you have any questions, please let me know.

Cheers,

- scott

Scott Libert
Control System Mentor
Team 2464 (Kauaibots)

Originally Posted by billbo911 (Post 1325906)

An alternative to the Nav6 board is this "Flight controller" for $35.

I believe your code would be a straight drop in, although a minor tweak may be needed.
It has a slightly better controller (AtMega2560), same IMU6050 and HMC5883L integrated on the board already.

Thoughts?

Originally Posted by James Lightfoot (Post 1325884)

We too are strongly considering a gyroscope "package" addition to our robot for the same reason as noted in later post: "Absolute" / persistent directionality. In that vein:
1) Have you put together that package you noted above?
2) If so, do you have a link to "high level" specifics?
3) What was the final price?
4) How do we place the order (direct or via the AndyMark website)?
5) How long after the order is placed will it be before we receive the kit?

Thanks

Originally Posted by slibert (Post 1325407)

We're working on locating a partner willing to develop a LabView VI for the nav6. When that happens, I'll be sure to let you know.

We will provide a free nav6 IMU and cables ($95 value) to whomever is first to step up and agree to develop and test a LabView VI for it - as long as they're willing to allow us to make that LabView VI available to others, and to allow us to modify it to include the nav6 'advanced' modes of operation. If you know of anyone interested, please have them contact me (scott@kauailabs.com).

Originally Posted by slibert (Post 1326028)

Thanks to all who have volunteered for this; I'm happy to report that a volunteer LabView library development effort is beginning, and we're expecting a beta to be available in approximately 4-5 weeks. I'll send out updates as things progress.

Originally Posted by Gdeaver (Post 1368538)

We did not use an IMU in competition yet but the testing we did do last summer indicated that with a game like this years game with the heavy defense and high G impacts would have yielded less than acceptable field centric control. IMU's that are perfect for our needs are out of our price range.