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Robot Electronics and Power - Answer Thread

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  • #16
    Compatible Sensors?

    Originally posted by FTC6081
    Under Rule 08 section n. number IV, are the following sensors compatible?
    We will be connecting them to the prototype board.


    A: It is impossible for the GDC to rule on the acceptability of all the various sensors that might be used by teams.

    Sensors should not pose any risk of interference with other robots, field elements, or field control. Examples of sensors that would violate this would be IR emitters, laser systems, RF systems.

    In looking at the three sensors you specifically asked about, the 3rd one would not be legal as it utilizes a laser for imaging the detected surfaces.
    The 1st also would not be legal as the wavelength it uses for sensing is in the Infrared range (870nm)


    • #17
      Multiple drive for motor?

      Originally posted by FTC0358

      Is it legal to connect two motor ports via combination of motor wires to power one motor?

      A: NO. Wiring a motor as suggested would risk damage to the motor and/or the motor controller, as well as create a risk of fire. As such this would be a violation of <S1> and is not allowed. A motor may be driven by no more than 1 motor port from a single motor controller.


      • #18
        Allowed Servos

        Originally posted by FTC6734
        Are all HiTec Servos permitted (continuous rotation, etc.) or can we only use the 180 degree servos that came in the kit?

        A: You may use any servo that falls within the constraints in <R05>.h


        • #19
          Switch connected to prototype sensor board

          Originally posted by FTC5290
          Would it be within the rules to use a V7-2B17D8-048 limit switch, connected to a protoboard, as a touch sensor.

          A: Yes. Make sure to be careful with insulating the connections.


          • #20
            LED Usage Clarifications

            Originally posted by FTC3785
            I know this was asked last year, but some of the applicable rules have changed:

            1. According to <R08>.s, "Visible light LEDs with their connected electronic circuits are allowed" Would an Arduino be acceptable as a "connected electronic circuit" if its sole function was to drive LEDs.

            2. According to <R08.>.s "LEDs used as visual cues must be controlled via connections to a HiTechnic SuperPro Prototype Board or the NXT Prototype Board." Must these LEDs be powered by the protoboard as well, or can they be powered separately but controlled by the board.

            A1: No. The intent of "connected electronic circuits" was to allow circuitry that was a part of the LED system in use.

            A2: <R05>.s allows the LED's to be powered in either of 2 manners; either from the robot battery or via a single battery of no more than 9v. The part of <R05>.s the requires control via the protoboard relates to the switching on/off of LED's as a visible signal to the team.


            • #21
              Legal Servo?

              Originally posted by FTC6934
              I have a few HiTec HS-322HD Servos from older FRC KOPs. I have found older FTC forum posts that said these are ok on FTC robot. I am assuming that they are. Just asking to be sure.

              A: Yes, as long as the mentioned servo is not modified from it's original manufactured state, it would be an example of a legal
              standard sized hobby servo.


              • #22
                Continuous Rotation Servo Legal?

                Originally posted by FTC6734
                Can we use the continuous rotation version of this servo


                or do we have to use the HS-485HB?
                A: No, the servo listed is modified by Servo City from it's original manufactured state and as such is not
                legal for FTC. Legal continuous rotation servos are produced as continuous rotation servos, without


                • #23
                  Legal Continuous Rotation Servos

                  Originally posted by FTC7197
                  Can we use any brand of continuous rotation servo or do we need to purchase the modified HiTec HB-485 servos from a vendor like ServoCity?

                  A: There is no requirement to use a particular brand of continuous rotation servos. All legal continuous rotation servos are manufactured as such by the original manufacturer. Servos modified from original state by anyone (retailers or teams) are not legal.


                  • #24
                    Specific Sensors on Prototype Board

                    Originally posted by FTC5290
                    Could either of these sensors be used as long as they are connected to a protoboard?
                    a) A LV-MaxSonar-EZ0 sensor for distance detection.
                    b) V7-2B17D8-048 Switches for touch detection.

                    A: This type of question has been previously answered. Please see Post #16 in the Robot Electronics and Power portion of the Forum


                    • #25
                      Replacing Battery Connectors

                      Originally posted by FTC0395
                      Q: In last year's competition, we had some issues with our power connections, and have considered the possibly of the battery to power switch connection as a possible cause. We use a lot of Anderson power poles, and were wondering if we can replace the connections on the batter with power poles, i.e. cut off the old connection (keeping the fuse) and using crimp on power poles. Thanks.

                      A: Yes. This is explicitly allowed by <R08>.x


                      • #26
                        2 Motors/Single Motor Controller Port

                        Originally posted by FTC7286
                        Is it possible to have two DC motors connected into the same ports? The rules say:

                        "f. A robot is constructed with either TETRIX or MATRIX motor and servo controllers, not both. Any quantity of
                        TETRIX (HiTechnic) or MATRIX Motor and Servo Controllers are permitted provided that the quantity doesn’t
                        exceed the technical specifications for these devices, the NXT, and the software. Motor controller outputs may
                        only be used to directly control DC motors. Servo controller outputs may only be used to directly control servos.

                        g. A maximum total of eight (8) TETRIX or eight (8) MATRIX DC motors are allowed and must be controlled by a
                        compatible TETRIX or MATRIX controller. A robot is constructed with either TETRIX or MATRIX DC motors, not

                        Any number of controllers is allowed. Does that make using a single port for two DC motors illegal?

                        A: It is legal to connect up to 2 motors to a single motor controller output port. Attempting to connect more than 2 risks damaging the motor controller and creating a risk to field and field personnel and is not allowed. Note that due to the way the motors connect to the Matrix Controller, it is not possible to connect more than 1 motor per port
                        Last edited by Buckaroo Banzai; 10-23-2013, 06:12 PM. Reason: clarification


                        • #27
                          Motor Controller

                          Originally posted by FTC0409
                          We have a problem with our motor controllers where the screw holes will break off, therefore making us unable to screw them to our robot. To fix this problem, we 3-D printed our own motor controller cases which we reinforced. However, we are unsure of whether this is considered modifying the electronics, since we only modified the casing and not the actual circuitboard.
                          A: Opening the motor controller case and replacing it with a custom printed case would constitute modifying electronics ans is not allowed.


                          • #28
                            LED's controlled via microcontroller

                            Originally posted by FTC0025
                            Can you interface an Atmel mC similar to the ATmega168 on a breadboard and use that to control an RGB led strip in a game-functional manner?

                            I'd like to consider adding RGB led light strips to both sides of the robot's undercarriage.

                            The light strips would be functional in the following manner.

                            - Prior to starting of the match, they would pulse a light teal color.

                            - When the match started the front half would display green, the back half red, indicating which direction is the front of the robot as relates to the controller. If the driver reverses the front then the leds also reverse. e.g. Either end of the robot can be driven "forward", the leds tell the driver which way is forward at any given point in time.

                            - During the 30 second endgame, the leds pulse purple, so our driver immediately knows it's the end game.

                            - I noticed that it's possible that the rack and pinion positions may get slightly out of whack and if that happens it's really bad as the whole robot gets torqued. Having a control mode where the motors on either side may be operated independently could be useful to correct this during a match. This is dangerous though and the leds would flash red if the controller was in this mode.

                            - When the match is over, revert to pulsing teal, but slightly faster than at the beginning to indicate the robot is tired.

                            A: The controller would be legal to add to the robot, if and only if it is controlled and powered by connections to a sensor prototyping board. Additionally, the robot may not perform any functional actions prior to match start or after match end. The pulsing lights as described pre/post match would be a violation of pre/post match functioning.


                            • #29
                              Chain Cable Carrier

                              Originally posted by FTC3785
                              IS this a legal part to use for holding our wires?
                              Igus E045-16-028-0 Energy Chain Cable Carrier, Polymer, EZ-Split Crossbar

                              Product Features
                              Very easy cable/hose installation
                              small pitch for low noise and smooth operation
                              Links can be easily added or removed to adjust length

                              A: Yes, this product is a legal COTS per rule <R08.t>


                              • #30
                                Extending NXT Cabling

                                Originally posted by FTC6035
                                I know that NHT (6-pin cable) extension are not permitted by rule and that HiTechnic is an approved source for those cables. Those cables come in a maximum length of 90 cm (~36 inches). The cable run our team needs exceeds that length. How do I work around this? May I use an extension jack ( sells 'extenders' which allow (1) approved cable to join with another approved cable)? HiTechnic indicated to me that this approach would serve my needs. Please advise.

                                A: There is no legal way to extend an NXT cable. The mindsensors extension jack is not a legal part. The 90cm maximum length is based on electrical limits within the NXT system.