Sensors

[Pierluigi Collina]

Subject: USB Mouse as Sensor

Question:

We have been planning on using an USB mouse as a sensor for odometry, and would like to clarify if it is legal or not.

Currently, it is an optical mouse with a visible red LED (https://www.hp.com/us-en/shop/pdp/hp...ky619aa-aba--1), plugged into a USB hub/splitter that connects to the Robot Controller phone (this splitter also connects the REV Expansion Hub to the phone). Software-wise, no modifications are made to the internals of the Robot Controller app; the mouse and its data are accessed through the Android USB Service (https://developer.android.com/guide/...ivity/usb/host).

The question is, is this kind of mouse, or any mouse in general used in this fashion, a legal part?

Does it immediately qualify as an "additional electronic" and thus is not allowed per <RE18>, regardless of the type of mouse? If this is the case, if we were instead to find a way to connect it through a REV Expansion Hub, would it then be allowed as a valid "compatible sensor" (<RE12>)?

Alternatively, would it be considered a video camera and permitted? If the issue is the red LED (<RE13>), if we switched to a mouse that used an infrared laser/LED, would that be allowed? If the issue is that it is not UVC-compatible (<RE14>), then if instead of an optical/laser mouse, we used a tracking ball mouse, would it then be allowed?

We can provide more details on software interfacing if needed, or on anything else for clarification.

Answer: The short answer - No. Your initial guess is correct - a USB mouse is not an allowed device by any other rule, so it falls under RE18 and is disallowed.

Sensors allowed under RE12 all connect to one of several I/O ports on the REV Control or Expansion Hubs; Analog, Digital, or I2C and are all accessed using standard HardwareDevice API's.

[Pierluigi Collina]

Subject: Alternative Rangefinder Sensor
Question: Our team wants to use Rev distance sensor but it is not available. Can we use following sensor which is not programmable and also uses same sensor as Rev distance sensor. Here is link -
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Answer: No. The only focused light source/laser sensor currently allowed is the REV 2m Distance Sensor.

[Pierluigi Collina]

Subject: COTS Potentiometer as Sensor

Question: This question has to do with the interpretation of rules <RE12>a ("Compatible sensors from any manufacturer may be connected to the REV Expansion Hub or REV Control Hub.") and <RE18> ("Electronic devices that are not specifically addressed in the preceding rules are not allowed.").

Rev Robotics markets a potentiometer for use as a sensor (by connecting to an analog port on the Expansion Hub).

Would other COTS potentiometers (of appropriate total resistance and connected to the Expansion Hub in the appropriate manner) be considered legal for use as sensors?

Thank you.

Answer: Yes.

[Pierluigi Collina]

Subject: I2C Encoder Interface Device

Question: As a follow-up item to the question about counting encoder pulses (quoted below), if one were to find a supplier of a legal pulse counter off-the-shelf, is it acceptable to use such a device with an encoder? The reason for asking is that there are only 8 encoder ports and i2c doesn't handle the pulse rate of typical encoders.

Answer: Under current rules, this would be considered in the bucket "Additional Electronics" and is not allowed.

[Pierluigi Collina]

Subject: Interfacing 5V Analog Sensors with a Rev Hub

Question: In past seasons 5V analog sensors have been legal when connected to a Modern Robotics Core Device Interface Module (which is no longer legal this season). We'd like to continue using such sensors this season, so are wondering:

1. Can 5V analog sensors legally be connected to a 5V power port on the REV hub? (This appears to be acceptable under <RE12(a)>)
2. Does a voltage divider, consisting of two resistors to lower the sensor output signal from 5V to 3.3V, fall under passive electronics in <RE12(c)>?
3. If (1) or (2) are prohibited, can you suggest a legal way to use a 5V analog sensor that doesn't work with a 3.3V signal?

Answer 1: Yes
Answer 2: Yes. Make sure to select resistor values appropriately! And remember to have a simple schematic ready in case your robot inspector has questions!
Answer 3: n/a

[Pierluigi Collina]

Subject: Microcontroller as Sensor

Question: An ATTiny85 works great as a hardware pulse counter. This can chip can be made non-programmable. We want to use the ATTiny85 as a voltage sensor for the signal coming from an encoder. In this way, we will have a sensor (encoder) connected to a sensor (voltage sensor). The ATTiny will be set as non-programmable. Is this allowed on a robot?

Answer: No. The ATtiny85 is inherently a programmable system and must be programmed at least once before it can be used. The limit on programmability is not a question of can it still be programmed, but rather of was it ever capable of being user programmed.

[Pierluigi Collina]

Subject: Intel T265 RealSense Camera w/ 3rd Party VSLAM Library

Question: According to a reply by the GDC last season, the T265 was ruled legal as it is and can function solely as a UVC camera. https://ftcforum.firstinspires.org//...5207#post75207
Just as a quick summary, the Intel Realsense T265 camera performs VSLAM (Visual Simultaneous Localization and Mapping) allowing one to localize and get relative pose. It is not directly programmable and all the processing is done onboard.

Since then, a member of the FRC community has ported his T265 wrapper from FRC for FTC use (https://github.com/pietroglyph/ftc265). The camera transmits the pose data through UVC. The T265 still functions like a webcam. So no external USB/other connection is made. It just uses the same USB connection as any other webcam and transmits the same UVC data. It should be legal by all FTC standards.

Just wanted to re-establish legality on the Intel RealSense T265 for this season and clarify if extracting pose data from the UVC stream is legal. Essentially, are we allowed to use the T265 and that library specifically in competition for localization?

Answer: Yes. Make sure to pay attention to power needs ... the T265 likely needs to be plugged into a powered USB hub.

Note that in general, ruling from prior years do not automatically apply to the current season. It is always a good idea to ask via the Forum if/when there are questions about component legality.

[Billie Jean]

Answers to questions about Sensors.