There’s the accelerometer, and the Hall Effect Sensor (2).
Are these two sufficient for sensors on the robot, and if not, what else would be useful?
Edit: My teammates seem to recall from the kick off video that the sensors provided in the kit would be sufficient, this is why i’m asking.
Thanks for replies
It is evident (by inspection of the code and inspection of the kickoff video) that the kickoff robot had gyro sensors and encoders installed. Neither of these sensors were included in the kit.
JMHO.
Something that helps software out is knowing where certain parts of your robot are. Pots (variale resistors) connected to moving arms, steering mechanisms, etc. can report back to software and help modify robot reactions and assist in auto modes.
Microswitches can be used to limit travel or sense when a moving part has just about reached it’s mechanical limit.
Wheel encoders/shaft encoders can be used to tell how far you have driven.
It depends on what you wanna do.
For the demonstration in the kick off I think the kit can be enough, depending on the programming and way of use.
Obviously, you’ll need more sensors for monitoring an arm, for example, or other specific function.
There is no gyro in the kit?
Leandro,
I believe that the demonstration robot used a gyro and encoders. Neither were in the kit. If you want to use them, you have to buy them.
No.
I know that a gyro can be used, actually I already used in an old project. I haven’t read all about the sensor of this year’s kit (which is not here yet), but I suspect that you can use for that function.
While a gyro sensor is not given in the kit and neither are sensors labeled “encoders,” FIRST does provide an accelerometer and 2 hall effect sensors. The accelerometer, with the right fine tuning, can give feedback similar to that of a gyro. Additionally, the hall effect sensors basically are wheel encoders.
I’d rather have the Silicon Sensing Systems GYRO-CRS03 gyro and Grayhill 61K128 encoders the kickoff robot used.
In the kick-off they said we have all the sensors we need inside the kit. they said we\d be getting a PID controller. does anybody know where that is? I can’t seem to find it in the code.
How can the Acceleration meter be used as a gyro?
are we allowed to purchase our own gyro sensors … from what i understnad is that the gyros were not allowed
Yes, you are allowed to purchase gyros just like last year as long as they meet the vendor and cost rules.
The PID system is available along with the scripting at www.kevin.org/frc. In my humble opinion, an accelerometer is a very poor substitute for a gyro. Last year we ended up disconnecting our accelerometer because all it did was eat up processing power. Remember the cool thing where Lavery jarred the robot, and then it righted itself? In my experience, accelerometors tend not to register sharp hits accuratly, they either over-, or underestimat the severity of the movement.
I’m not clear myself what a gyro sensor is, from what I’ve read and looked through, its some rotation sensor of some sort?
Anyone want to help clarify this for me?
In robotics, it is properly called a yaw rate sensor. It’s output is proportional to the velocity if angular rotation rather than the acceleration of other G sensors. This means that there is one less integration required to determine angle versus the double integration of an accelerometer required to give Cartesian coordinate position.
The reason that a YRS give velocity rather than acceleration is that is uses the Coriolis effect in its design.
Having said all this, you have enough info to Google away. If you have more questions after some investigation, fire away…
Usually their called “angular rate sensors”. We got one last year from Digi-Key, I think it was the Analog Devices ADXRS150, get the version that has the Evaluation Board with it. It basically registers a voltage change when it undergoes an angular acceleration. If you integrate angular acceleration, you can determine the amount of angle it has turned. This is more useful than dead reckoning or counting wheel / tooth rotations since it depends only on what is happening physically to the robot. Dead reckoning and wheel encoding depends on the wheels not slipping and not hitting anything in its way.
Now has anyone checked to see if the linear accelerometer that is included in the kit have a high enough resolution to be useful? The spec sheet didn’t seem to convince me.