VEX Gyroscope and Accelerometer Information

[Quazar]

Originally Posted by Edmund Harfmann

For the accelerometer, will it use one big connector (for 3 sequental port) or will it use 3 connectors so that you could plug it into ports 1, 3 and 8?

I predict they will be separate for two reasons:

1. IFI already has the single-port connectors in production and there isn't much advantage in a new part if it isn't needed
2. Having them separate allows you to use the minimum number of ports if you don't need all three axes for a given design.

Cheers,
- Dean

[MarkO]

Originally Posted by Quazar

I predict they will be separate for two reasons:

1. IFI already has the single-port connectors in production and there isn't much advantage in a new part if it isn't needed
2. Having them separate allows you to use the minimum number of ports if you don't need all three axes for a given design.

Cheers,
- Dean

Good Call on both points.

I guess that there are times when only One or Two Axis would be needed.

[vexbot]

Originally Posted by Quazar
I predict they will be separate for two reasons:

1. IFI already has the single-port connectors in production and there isn't
much advantage in a new part if it isn't needed
2. Having them separate allows you to use the minimum number of ports if
you don't need all three axes for a given design.

Cheers,
- Dean

That's what I would have said too.

Depending on what you are using the Accelerometer for you might only need to use 1 axis. Using separate cables for each axis allows more flexibility for us users to chose which axis we want to use and which analog port we want to put it on. Plus, you wouldn't need a special cable.

[Edmund Harfmann]

That makes way too much sense. I'm playing around with updating the MSRS services to include some of the new 'toys' and trying to figure out how it should be implemented. Sadly, that complicates the interface somewhat.

Oh well. Just have to think about it some more.

Thanks (I think :>) for giving me a different viewpoint.

Ed

[Quazar]

Originally Posted by Edmund Harfmann

That makes way too much sense. I'm playing around with updating the MSRS services to include some of the new 'toys' and trying to figure out how it should be implemented. Sadly, that complicates the interface somewhat.

Well, if it is three connectors, then I'd just model it as instances of single-axis accelerometers. The fact that the three wires all go to the same sensor unit is not really important - from a software perspective, they could just as easily go to three separate single-axis units.

Cheers,
- Dean

[Edmund Harfmann]

Sounds like a good approach. Originally I was thinking of how to match each axis but as you say it doesn't matter at my level. That is for a higher level of abstraction. It will mean that each accelerometer could be 'miss programmed' with the gain different, but I'll leave that as an exercise for the user to realize....

[vamfun]

Originally Posted by Bob Mimlitch

Then we added three rail-to-rail op-amps on the output to bring the voltage back to 0.05V - 4.95V.

So do we use the 0 to 5v or .05 to 4.95v for scaling?

Unless told otherwise, I'll assume its 0 to 5v.

So the new Vex output scaling for the 1.5g range will be :

800*5/3.3= 1212 mv/g

The zero g bias 1.65v*5/3.3 = 2.5v

I guess the next question is how have you affected the bias, scale and noise errors with your amplifiers?

What is the signal conditioning of your board? Do you have an added 1 pole filter or are you just using the 1k,.1uf filters on the freescale chip. It would help if you posted a schemetic so we can know how to change the pole cutoff with additional capacitors.

Perhaps you can add some of this info to your product website since the freescale stuff no longer applies directly.

[MarkO]

Originally Posted by Brandon Martus

VEX Analog Yaw Rate Gyroscope V1.0

The VEX Gyro measures turn rate, so it can be used to calculate how much a robot has turned. This allows for very precise turning (example - you can program the robot to turn exactly 90 degrees to the left). Using the VEX Gyro a programmer can also adjust for any drivetrain drift; this turning correction can be used to ensure a robot drives straight. The Gyro could also be used to create a self-balancing robot and to measure robot tilt (such as detecting if the robot is on the ramp or tipped over).

• ±300 degrees per second full scale
• 0-5V analog output
• Uses the LISY300AL chip
• LED indicated power and proper connection
• Mounts directly to VEX
• Price: $49. Availability: November 2008

LISY300AL Chip Information:
The LISY300AL is a low-power single-axis yaw rate sensor. It includes a sensing element and an IC interface able to provide the measured angular rate to the external world through an analog output voltage. The sensing element, capable of detecting the yaw rate, is manufactured using a dedicated micromachining process developed by ST to produce inertial sensors and actuators on silicon wafers. The IC interface is manufactured using a CMOS process that allows a high level of integration to design a dedicated circuit which is trimmed to better match the sensing element characteristics. The LISY300AL has a full scale of ±300 °/s and is capable of measuring rates with a -3 dB bandwidth up to 88 Hz.

<<< SNIP >>>

Is there any Status on this Product???

[Rick TYler]

Originally Posted by MarkO

Is there any Status on this Product???

Mark, it's been for sale for quite a while (we have one): http://www.vexrobotics.com/vex-robot...erometer.shtml

[MarkO]

Originally Posted by Rick TYler

Mark, it's been for sale for quite a while (we have one): http://www.vexrobotics.com/vex-robot...erometer.shtml

The accelerometer, yes, I have now too.. I was inquiring about the Gyroscope V1.0. They are different things... MORE TOYS!!! I mean tools...