What sensors do your teams use
 

So our team is looking at investing in more sensors and we were just wondering what other teams out there use.
Edit: We mostly use encoders, Gyros, Limit switch and distance sensors. but we are more wondering where other are getting senors for the past couple years we have been using Vex sensors because thats all we had.

Thank you for your time

Re: What sensors do your teams use
 

Can you give a little more detail as to what type of sensors/what purpose you would want them for?
EDIT: (I probably can't help you, but rather I myself want to learn the different uses of common FRC sensors)

Re: What sensors do your teams use
 

We use/have used:
- encoders
- gyro
- break beam sensors
- limit switches
- Vision camera
- distance sensors

Re: What sensors do your teams use
 

we are mostly interested in what ASD20 stated. Well we want to use Encoders and Gyros for our Autonomous so we can drive in a strait line and have better control on how we can code our Autonomous. The Distance Sensors and Limit Switches are mostly was stopping something, for example this year we did have a distance sensor to stop our in-take motor that would collect the bolder so it wouldn't burn the motor out.

i hope that helped

Re: What sensors do your teams use
 

What type of distance sensor?

Re: What sensors do your teams use
 

I dont know the type off the top of my head right now but ill see in any of my team members know. i do know it came from FTC

Re: What sensors do your teams use
 

Ultrasonic/Sonar? LIDAR/Laser/IR?

Re: What sensors do your teams use
 

Teams use more sensors not just because sensors are awesome, but because there is useful info to gather. This info can be used to make a more effective and robust robot.

If I were caught on a desert island and could only bring a few types of sensors with me, here's a few things I'd consider:

#1 - Encoders. Accurate measurement of wheel velocity and distance traveled on a drivetrain is crucial for a consistent autonomous routine. Also for consistency in wheeled shooters... Anywhere you would like something to be going a certain speed or distance, encoders are a better solution than hardcoding a motor control value.
One option: http://www.andymark.com/product-p/am-2899.htm

#2 - Gyroscope. Generally, the more expensive the better. Gyro gives you rotational velocity of your robot. By integrating (accumulating) it over time, you can deduce the angle of your robot relative to the angle you started the match at. This is very useful for autonomous navigation.
http://www.analog.com/en/products/me...-evaluationkit

#3 - Lidar Lite. This nice little sensor measures distance with a laser. By pointing it out the front of a bot, you can figure out how far you are from a wall, tote, or anything else solid. Useful for autonomous, or for helping the drivers position the robot.
http://www.robotshop.com/en/lidar-li...FQgzaQodcHAIUQ

#4 - Pneumatic pressure analog sensor. Allows the drivers to see how much air they have in reserve. Not used all the time during competition, but helpful for diagnosing issues when you can't walk out to the robot to check on it.
http://www.andymark.com/product-p/am-3219.htm

Re: What sensors do your teams use
 

We used this SPI port gyro that was designed to plug directly into the roboRio. Worked great. It's based on the Analog Devices ADXRS450 digital gyroscope chip. You can buy that chip in different board configurations. I'm not sure where to buy this specific packaging.

http://firstchoicebyandymark.com/fc16-000

I've heard good reviews from the NAV-X gryo / accelerometer board although we've haven't used it yet. It's definitely available for purchase.

http://www.andymark.com/product-p/am-3060a.htm

We use a Grayhill 63R optical encoder for measuring drive train distance traveled by coupling the encoder to a live axle on a wheel or the main gearbox. This technique works good for autonomous if you limit acceleration to prevent wheel slip.

http://www.digikey.com/catalog/en/partgroup/63r/11554

Good luck with your research and testing.

David

Re: What sensors do your teams use
 

We use a navx and I think it works well, even though I'm pretty sure our programmers have broken like 3. But then again, programmers break everything.

Re: What sensors do your teams use
 

1678 likes to use Banner laser photo eye sensors for detecting balls, other objects, and sometimes field elements.

Re: What sensors do your teams use
 

Thank you everyone thing is really helpful for us.

Re: What sensors do your teams use
 

We used the CTRE magnetic encoders on our shooter to measure velocity, andymark's string potentiometer to measure position on our arms, these grayhill encoders on our drivetrain to measure velocity for (theoretical) automatic shifting, and a navx on our drivetrain for straight driving. I'm sure there are one or two sensors I am forgetting, but all of these are in closed loop P, PD, or PID control schemes. If you have any questions about how any of this works, let me know. :)

Re: What sensors do your teams use
 

I gotta give a shout out to the humble potentiometer. We picked up a handful last year, and they proved super usefull this year too. They wire directly to an analog in Port, and can essentially give you abaolute position of a mechanism. Getting some with more than 300deg of rotation help protect it in case of over rotation.

Here's two versions I recommend keeping around:
Continuous rotation: http://www.digikey.com/product-detai...-103-ND/274005
10turn: http://www.digikey.com/product-detai...03L-ND/2058386

Re: What sensors do your teams use
 

One other question for you guys/gals as you discuss your sensor needs:

Are there any broad areas of sensing technology, how to do sensor integration (mechanical, electrical, programming), etc that you feel your teams could use help with?

AKA, in addition to WHAT to use, do you feel there are adequate resources on HOW/WHY to use sensors, that could be addressed by linking existing content or creating new content specific to FRC?

Re: What sensors do your teams use
 

I too would like to help my team improve their use of encoders.

I'm most interested in encoders that could be used for flywheel shooters that don't require any machining to install. In 2012, I remember teams used light emitting sensors to count light and dark marks on a spinning disk.

Are these still viable?
If so, which ones work well (high reliability, easy installation, non-contacting) and are reasonably priced?

Dave
Build Mentor 2976

Re: What sensors do your teams use
 

Dave,
What you're referring to is a simple IR beam break sensor (example: https://www.adafruit.com/product/2168). One of the modules is just an IR LED, and the other is a receiver that tells you if it sees the LED or not. I don't see any problem with the electronics not being reliable, but you would have to manufacture you're own spinning disk to serve as an interrupter. Those adafruit ones seem pretty straightforward to mount, but I'm sure there are some better ones out there that come in a single module.

While I think mechanically attaching a proper high speed encoder would be the right solution for a flywheel shooter, these are still pretty useful. You can use them as limit switches and even "linear encoders" with the right interrupter.

Re: What sensors do your teams use
 

If you are spinning it fast enough (quite likely), you can put the light/dark pattern directly onto the disk, and use a reflective optical sensor. If you do this, use a relatively inexpensive sensor and be ready to replace it, because it'll be located right next to that spinning wheel, and FRC robots have been known to collide with one another or the field elements. On occasion.

Re: What sensors do your teams use
 

You can also use a $10 hall effect sensor to do the same thing with a magnet. We found this pretty effective this year.

Re: What sensors do your teams use
 

If you want easy to install, I would recommend encoders that are designed to fit directly on a motor or gearbox. Vex sells a VersaPlanetary encoder, which is easy to assemble and fits right into a VersaPlanetary gearbox just like any other stage. This is what I would recommend for a shooter encoder. Andymark also now sells there PG gearmotors with encoders built in. The only assembly required is plugging in a wire. They also sell a CIMcoder now, which is designed to fit right on the shaft of a CIM. I have not used this before, so I can not speak to how well it works or how easy it is to install, but I imagine it is pretty straightforward. Andymark also sells an encoder that fits directly onto most of their gearboxes. It is kind of a pain to install and my team has broken way too many of them, but it is probably the easiest way to get an encoder on your drive train.

All of these require no machining and interface nicely with other COTS components.

Re: What sensors do your teams use
 

Do you have a source for these? 469 used a ton of them as well when I was on the team, but I've found it hard to source them at a reasonable price.

Re: What sensors do your teams use
 

For wheeled shooter speed measurement we've had good luck with this gear tooth sensor from Allegro Microsystems:

http://www.allegromicro.com/en/Produ...Cs/ATS667.aspx

As long as you can get the face of the sensor close enough to the teeth of a ferrous metal gear, you'll see one pulse per tooth that passes. They're around $7 each.

Re: What sensors do your teams use
 

While we haven't done any laser products, we've bought plenty of relatively inexpensive sensors including IR, optical, and ultrasonic rangefinders and interruption/reflection sensors at robot shop, Lynxmotion, Jameco, DigiKey, and others.

Re: What sensors do your teams use
 

I've grabbed a few off ebay a few times. Just make sure to look the exact model number and make sure it meets your specs.

Re: What sensors do your teams use
 

We use the Grayhill 63R on the drivetrain. Last year, we used the gyro on the Spartan Board--it worked great, and we likely will use it again.

Like others, we have used banner sensors/photo eyes for no-contact object tracking in the past.

We used 4 VersaPlanetary integrated encoders on our shooter wheels, scaler, and portcullis device this year. Provided you manage your ribbon cables properly and know how to match the direction of the encoder with the direction given by the SRX, I would highly recommend them.

Re: What sensors do your teams use
 

gyro&accelometer - for PID and stuff i think...
microswitch - to know if the ball is secured inside the robot
magnetic door sensor - to know if the scaling arm lifts the robots high enough for the scale to count

Re: What sensors do your teams use
 

We used the built in accelerometer of the roborio as a tilt sensor.

This year, in autonomous, we had a problem. Our robot was top heavy. If we tried to get over obstacles in autonomous, if we went too fast, we tipped. If we went too slow, we got stuck. The tilt sensor was our salvation. You can see it in action in this youtube video.



https://www.youtube.com/watch?v=roVc581joiA

As 247 goes over the moat, the announcer indicates that we look stuck. What you see on the film is that we drift back to the back side of the moat, and then suddenly charge forward.

Well, the drift isn't a drift. We programmed it to wait two seconds and check the tilt. If we weren't on flat ground, we would go slowly back, and then gun it full speed to finish the job.

It worked quite nicely. We also used it as an anti-tip sensor. If the tilt got too high, we cut wheel speed or moved in reverse to prevent tipping. That one didn't always work, as seen in the same video at about 1:10.

Hey I was thinking the same thing by using the gyro as an anti-tilt. Can I ask how effective that was at saving the bot from tipping? I might try it out my self next time we have a tall bot challenge.

Sent from my SAMSUNG-SM-G900A using Tapatalk

Re: What sensors do your teams use
 

I've seen a number of resources online of various qualities, but it would be nice to see a single published whitepaper that describes how to design a robot sensing system from top to bottom.

Challenges with such a document:

• Keeping it up to date with changing technologies and parts availability.
• Satisfying a large range of audiences.

I'd expect some mentors or students don't want to think about sensing system design much, and just need a quick answer as to "what should I use for situation XYZ". Others will have this design experience, and just aren't familiar with what's commonly used for FRC...

Perhaps a community-maintained wiki for this (and other topics) is an option? I haven't seen one yet, although I haven't looked very hard either...

EDIT: After a brief amount of searching, I came across https://firstwiki.github.io/wiki/tech , but it looks like there is plenty of work to be done still.

Re: What sensors do your teams use
 

We use students as limit switches... the robot runs into them and they let us know about it. Decent feedback but a little slow and if they get hit too hard then they stop working sometimes. The good thing is we seem to have a never ending supply of them for replacements.

Re: What sensors do your teams use
 

I cannot even think of recommending the CIMCoder. We had four of our drivetrain and by the time we reached competition, only two were reporting any information. I've also heard some horror stories of the shell cracking on high vibration applications like a shooter.

YMMV

Re: What sensors do your teams use
 

Agreed. They need to be solidly filled and not a shell. Additionally, it would be nice if the little black square was actually a square and not a rectangle. Cranking down on it with the wrong orientation will crack the housing. It has a lot of potential but it needs some revisions.

Re: What sensors do your teams use
 

Same here! We have some good video demos of using our student limit switches in autonomous mode:
https://www.youtube.com/watch?v=WumkMeRE6Iw

Seriously though, this year Team 4276 used the following sensors:

Optical encoders (drive)
LIDAR (drive, tower distance)
Gyro/Accelerometer (rotation and inertial distance measurement)
Hall Effect Switch (arm position reset)
Hall Effect Counter (gear tooth sensor -- shooter wheel sped control)
Rotary Encoder (Arm position)
USB Camera (Telemetry/Drive Vision)
2nd USB Camera (Autonomous target detection)
Vex Pushbutton Switch (intake ball detection)

Re: What sensors do your teams use
 

As I remember our programming team also used the lab wall as a limit switch. Good thing our school's facilities guys are good with sheetrock.

Our actual list from this year :

line break sensors
lots of encoders (wheels and turret)
Stereolabs ZED depth camera

Probably missing something, but those are the major ones.

Re: What sensors do your teams use
 

We try not to use students or our build space as a limit switch; wouldn't want to damage the robot.

Re: What sensors do your teams use
 

Our robot this year had the following sensors:

• 2 Optical Encoders for our Drivetrain*
• 2 Magnetic Encoders for our flywheel shooter
• Potentiometer for our actuating wedges
• Gyro
• 2 Cameras**

*In the offseason, we switched those out for magnetic encoders because one optical encoder never seemed to work (despite switching everything out from shaft to port.

**We got vision working in the offseason

Re: What sensors do your teams use
 

Then how do you train your pit crew? :ahh:

Re: What sensors do your teams use
 

I said try not to, not don't. Don't worry, pit crew gets plenty of training :)