Hi, I’m a first year programmer and was wondering what sensors you are/want to use in your robots. I currently have an inertial sensor and some bumper switches in our robot that do pretty basic functions and was thinking of adding a vision sensor to track the field elements (although I’m debating on whether the time loss would bring any real improvement than not using it at all). I’m just curious as to see what the other teams are doing and am sorry if this is too intrusive. Thank you.
If you have the funds, gps sensor is a fun piece of tech
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I saw that you need field code strips so the GPS sensor can work in conjuction with it. I mainly play in rec tournaments and I don’t think I’ve ever seen them before. Are they at every tournament or will I need to supply my own?
GPS Field Strips will be required for all skills fields starting October 1st, however it will be optional to have for tournament matches, so I wouldn’t rely on that sensor for any non-skills matches
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Oh wow yeah, I will definitely look into that cuz it sounds like it would be faster than using a vision sensor. Do you have any other recommendations for the 15 second autonomous in an actual match? I was thinking of maybe using a line sensor to detect lines as a constant to be more accurate but am unsure of its usefulness. Thanks for all the help.
Some good thoughts are:
- Either V5 Rotation Sensor or Encoders for tracking wheels
- V2 Potentiometers for your arm (The V1 red potentiometers are kinda finicky, so I hope the V2 is better)
- Inertial Sensor (Its a relatively precise gyroscope and accelerometer)
- Color sensor to detect when an object goes through a system, or using a line follower sensor
- Limit switches are really good for programmed hardstops
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the vision sensor is a fun thing to play with in a controlled setting, but in real world conditions I’m of the opinion that it has little practical application. It’s just too sensitive to lighting conditions, and is relatively poor at differentiating objects unless there is a ton of contrast and light in the environment.
I also wouldn’t get a gps sensor, at least not yet. It’s fairly expensive, and we’ve yet to see how it compares to a more traditional position tracking method using wheels and/or an inertial sensor.
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Ah ok, I will definitely research more into whether the vision or gps sensor is actually any good to use for my needs. Thanks for your help
I know the motors already have a encoder built into them. Are they good enough or should i get the actual sensor? I did program a pid using the default motor encoders, would the encoder/rotational sensor be able to produce a noticeable difference in accuracy?
What would the potentiometers be used for? I’m having some trouble thinking of a use case for them.
the motor encoders are accurate, but there are a few reasons why using external sensors might be better.
For something like a tracking wheel, there is no motor to read an encoder from. so you need an external sensor. And for something like a lift or a pivoting joint, a potentiometer will give you the absolute position of this pivot, rather than the relative position the motor will give you. this means the sensor value will be unaffected by the starting position of the motor, or any slop between the mechanism and the motor, which can make it more reliable
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Oh ok I see why the potentiometer might be useful, but our robot does not have a tracking wheel. However, I have searched the forums a bit and found that the IMEs have more issues in a gear drivetrain. Idk if this is true or not, but would that be a reason to use external encoders?
eh, I’ve never had an issue with a drive gearing causing too much slop for the motor encoders to be accurate. The main source of inaccuracy is if the wheels skid, because then the encoders think the robot has moved when in reality it’s just skidded in place for a bit. That’s the purpose of a tracking wheel.
but you can mitigate slippage by accelerating slowly and still have a reliable auton without tracking wheels, they just make higher level programming more accurate.
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Ah ok, since I’m still not too sure about my programming skill, I’m going to probably put these at a lower priority because I don’t think my programs going to be that high level. But if I somehow become a programming god, I’ll definitely use external encoders. Thx so much for the help.
This is true and important. Keep in mind, however, that according to Q&A 814, teams are permitted to use the GPS sensor on all fields in which the fields strips are present. I don’t know how effective the GPS sensor will be as our field code strips are back-ordered but I hope that it will be accurate enough to use for reliable programming skills.
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