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  • Sensors

    Answers to questions about sensors.

  • #2
    Originally posted by FTC0365
    Subject: Intel RealSense Tracking Camera T265

    Question: Hi,

    Our team is looking at the Intel RealSense Tracking Camera T265 model, a camera that can perform Simultaneous Localization and Mapping (SLAM) functions. It makes no use of lasers, only two fisheye lenses and embedded electronics that take care of the SLAM computation. The device has a USB cable (UVC compatible) in which position data is received and has no features that would interfere with other robots' Autonomous or TeleOp routines.

    Since the device is only a camera with inbuilt processing (similar to the already allowed Pixy Camera in a previous season post), is this allowed for competition use? In addition, it is not a directly programmable camera and passive only. There is an Android SDK available to support development.

    T265 Camera:

    Specs sheet:


    MOE 365

    Answer: Yes.


    • #3
      Originally posted by FTC7171
      Subject: USB Web Cameras

      Question: What type of webcams are allowed for sky stone detection?

      Answer: There is no list of allowed cameras. Any USB camera that is UVC compatible is allowed - see Game Manual Part 1 <RE13>


      • #4
        Originally posted by FTC11081
        Subject: I2C Interfaces for Non-I2C sensors

        Question: Especially with the dropping of Modern Robotics Motor Controllers in the 2020 season, the choices for quadrature encoders are limited. We were wondering if a sensor to convert quadrature output to an i2c input such as
        would be legal. It seems to satisfy all applicable rules, as it is not programmable, and can be connected to the Rev Expansion Hub.

        Answer: Under current rules, this type of interface board would fall into the "<RE17> Additional Electronics" portion of the rules and not be legal/allowed


        • #5
          Originally posted by FTC13296
          Subject: Seeking Approval for Custom Sensor Module

          Question: Our team has been developing an optical XY odometry module. We would like to submit the module for approval and share the module design for use by other teams. We have not come across anything in the FTC resources that provides a procedure for this. Is there an official procedure?

          To begin the dialog, let us provide a brief overview of our module.

          Our module implements an XY optical odometer with a resolution of 100 counts per inch in either axis. The module connects to two Rev encoder ports on the Control or Expansion hub. The module draws minimal power from the 3.3v lines of the encoder ports. The module produces two wire quadrature signals just like any ordinary optical encoder.

          The module uses a commercially available optical sensor (used for open source gaming mice). The sensor has a SPI interface. To translate from the SPI interface to the quadrature encoder signals, an arduino "teensy" is used. We understand that RE17 disallows the use of programmable boards. However, our module does not allow access to the programming capability. We view the function of the teensy more like an interconnect or bridge.

          While reviewing the FTC resources and forums, we came across the forum thread ( The thread included a comment in a ruling: "If it is used in a module that does not include the user programming, it would be allowed."

          We view the module similar to a Rev 2m sensor, the PixyCam or even the recently approved Intel RealSense T265 tracking camera. These are purpose specific modules that include a processor but does not expose it for use. In our specific case, there is no access to the processing capability other than the quadrature outputs.

          We realize you will need more than this brief overview for a ruling, but we first wanted to see if there was a precedent. We can provide pictures, links to part datasheets, schematics, power draw, cad files, assembly details and the code running on the teensy as needed.

          Team 13296 TiGears

          Answer: The module as described violates RE17. It is a custom circuit and contains an arduino that is programmed by the user. There is no process for getting it approved. The other sensor modules you mentioned are all commercial products, not team built modules. The post you referenced is a couple of years old. The allowance for SPI-I2C bridges to control LEDs was rolled into a generic interface module description in RE12.c - explicitly only for control of light sources.


          • #6
            Originally posted by FTC14353
            Subject: Flow Sensor Legality

            It plugs into the hub's DIO ports and can be read as a normal quadrature encoder.

            Answer: No. The sensor uses an embedded IR laser and violates RE12.a as a result


            • #7
              Originally posted by FTC7854
              Subject: Modified Vex Sensors
              Question: We would like to take either the Vex bumper switch or the bumper switch v2, take the casing off, and 3d print the electrical parts into our claw. In essence, make a 3d printed touch sensor. If we print it so the sensor can be assembled so the electrical components are configured in the same manner as the original bumper switch, would it be legal? It would use COTS electrical components, but with a custom 3d printed case instead of the red and gray plastic it comes with.

              Answer: No. This is not a modification, but rather a disassembly and reconstruction using parts of the original sensor.The modifications described appear fall under the "modified internally" portion of RE15 ... i.e. the entire internals are removed and built into a completely separate device.


              • #8
                Originally posted by FTC11104

                Subject: Breakout Board for Analog Sensor Chip

                Question: Hello,

                We would like to know if the following contraption is legal.

                An analog voltage sensor is mounted to a team-designed PCB that contains only the sensor and passive components as recommended by the sensor manufacturer.

                The way we read the rules, this is legal. Rule <RE11> d. states that “Voltage sensors are allowed; except on an output port of a motor or servo controller.” Our voltage sensor should be legal, since it isn’t being used in either of the exempted scenarios.

                Additionally, a forum by the title “Custom Sensor PCB” asked by FTC 6081 on 11/22/2016 asks the question “Is it legal for a team to use a sensor if it is a manufactured sensor mounted on a custom printed circuit board containing only passive components as recommended by the sensor manufacturer?” The GDC answered, “Yes. Be prepared to show a schematic of the circuit to the inspectors and discuss/describe the design as part of the robot inspection process.”

                See the attached diagram for more context.

                Is our described part legal?


                Link to referenced forum post (#9 on the page):

                Answer: <- deleted original "yes" answer ->

                Update: It has come to our attention that the actual usage of the breakout board was NOT to use it as a simple sensor, but as a multiplexer to allow access to several sensors. The ruling is amended to a NO, as a sensor multiplexer clearly violates the "additional electronics" portion of the robot rules.
                Last edited by Pierluigi Collina; 03-12-2020, 12:20 PM.