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Robot Inspection and Build Rules - Electrical - Answer Thread

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  • Han Solo
    replied
    Can Teams Repair Damaged Modules

    Originally posted by FTC5414
    Modern robotics is offering a service to fix PDMs that have damaged regulators and USB ports. If a team has the ability to make the same repair for a fraction of the cost. Is this allowed?

    We are specifically interested in replacing a broken USB port on our otherwise perfect PDM. We would be replacing it with an equivalent USB port and it would be done by a professional with plenty of experience in electronics repair. We can get the part to fox this for less than $1, where it would cost $30+ to ship it to Modern Robotics to be fixed.

    Thanks,
    Team 5414


    A: No. Modern Robotics repair service is the only allowed option for fixing damaged modules.

    Leave a comment:


  • Han Solo
    replied
    LED Powered from Core Device Interface

    Originally posted by FTC8686
    We were wondering if it is allowed to power a LED as a status indicator off of the PWM ports on the core device interface module. We have two LED's that flash alternatively and they will stop flashing if the program stops(if we disconnect, program crashes, etc). We assume that these are allowed as the interface module takes power from the core power device module, so its coming from the same source.
    Thanks! - FTC8686


    A: No. <RE03>.g specifies the allowed power sources for approved light sources. The Core Device Interface is not one of those power sources.

    Leave a comment:


  • Han Solo
    replied
    Voltage Regulators and Converters

    Originally posted by FTC6559
    Although rule <RE03 - h> forbids the use of voltage converters (and rules on forum questions state we shouldn't ask since it is already a rule), we would like to ask if a 12 volt voltage regulator may be used to stabilize the power output from the batteries to the PDM to a fixed 12 volts. FTC is currently aware of USB connection issues in relation to the batteries. ( http://ftcforum.usfirst.org/showthre...during-scan%29 ) When the batteries are low they give off ~9.5 volts rather than 12. This low voltage is then further stepped down in the PDM to power the USBs, but if the input power is too low, the USBs fail. We feel that a voltage regulator between the battery and the PDM would alleviate the issue, allow teams to fully utilize their battery power, and correct any other issues that may be caused by voltage. Allowed 12 volt Batteries that have full charge have a voltage of ~14 volts, which widens the range of voltage, and could also potentially lead to issues, though it is unlikely. A fixed 12 volt regulator can be bought for as cheap as $1.50, making this easily accessible to almost all teams.

    Q: Since voltage regulators are currently disallowed, would it be okay in this instance to use one, or that one is allowed in the rules for this specific purpose, even if it is strictly outlined to one brand, one model, and one use?

    ~Thank you for your time
    Team 6559 Geared Reaction


    A: No. There are no allowed voltage regulators or converters. <RE03>.g explicitly disallowed power adapters or voltage converters. <RE06>.d disallows "Other electronics" (i.e. voltage regulators)

    Leave a comment:


  • Han Solo
    replied
    12v MATRIX Motor/Servo Controller

    Originally posted by FTC10877
    We have asked Modern Robotics Inc. for more MATRIX 9.6V motors (14-001 and the like), as our robot is built on it and we have invested in the system significantly. However, MR has told us that they don't have any more of the motors, which is quite frustrating. The RES-Q game manual suggests that we are allowed to use motors like the AndyMark AM-3102, can you confirm that this is accurate? If we are unable to source compatible, permitted motors then we will not be able to compete effectively with other teams, and will have to purchase even more motor controllers, motors, and batteries. If there are any other motors that we can use with a 9.6V Legacy Module/MATRIX system, please let us know.

    Additionally, we are considering using 12V batteries and replacing our motors with 12V versions as the 9.6V can sometimes be slow. Will 12V cause damage to the MATRIX Servo Controllers, which appear to be rated at 9.7V? Thank you.


    A: Given that Modern Robotics is selling MATRIX 12v batteries and motors to use with the MATRIX system, it would be reasonable to assume that they are compatible with the MATRIX Motor/Servo Controller.

    Leave a comment:


  • Han Solo
    replied
    Yet Another Servo Clarification

    Originally posted by FTC9791
    Under ruling #72 that reiterated the previous stance on servo manufacturers, is the following action legal?
    A student affiliated with the team, acting independently from the team, takes a power window motor (or similar) which in its current state is classified as a motor, and then designs and builds controller circuitry that turns the motor into something that uses feedback and is compatible with the servo controller - a servo, according to the best definitions we can find online or in the game manual. The student then gives the newly-manufactured servo to the team.

    If this action is not legal, what rules prevent it and why?

    Thank you,
    9791


    A: No. This is an assembly of parts that are individually not allowed. The student does not qualify as a servo manufacturer. <RE04> constrains motors. <RE06>.d constrains all other electronics

    Leave a comment:


  • Han Solo
    replied
    LED's in parallel with Motors or Servos

    Originally posted by FTC7842
    May we wire an LED and appropriate resistor in parallel with servos or motors? The are passive components and would be powered through the core power distribution module.


    A: No. The described connection would not be allowed. The LED as describe is NOT powered by the Core Power Distribution Module (it is powered by a motor or servo controller)

    Leave a comment:


  • Han Solo
    replied
    Custom LED Controller Allowed?

    Originally posted by FTC8862
    Robot electronics answer #62 comes very close to answering my question, but it asks about a COTS decorative light controller. Would a custom-built controller circuit for LED lights be considered part of the "light source," or would a custom-built controller circuit also be considered "other electronics?"

    Sorry to press the point, and thank you for clarifying

    Matt


    A: A custom built controller would fall under <RE06>.d and not be allowed.

    Leave a comment:


  • Han Solo
    replied
    Definition of Servo Manufacturer

    Originally posted by FTC9791
    Hello,

    Ruling #33 and its followup #41 are somewhat unclear, and seem rather backwards when interpreted in the strict sense. They appear to extend the limitations of modifications on servos specified in <RE02> to the sellers, not just the manufacturers. Therefore, is the onus on the teams to ensure that their servo vendor has not made modifications (i.e. contact the seller if the listing is unclear), or is it simply that a servo which is advertised as modified post-manufacturing is illegal? In addition, what exactly is the definition of a seller versus a manufacturer? Our interpretation was that a manufacturer is any entity that took components that do not qualify as a servo, and then modified or machined those components into something that does qualify as a servo. Under <RE02>, the team cannot be the entity that is the manufacturer. However, a custom-servo manufacturer could be the entity. This seems to be a bit backwards, as a team could order a custom servo to circumvent any <RE02> rule, while being forbidden from customizing servos themselves.

    Thank you,
    9791


    A: A servo manufacturer is the one that creates the servo initially. Any modifications made to a servo post-manufacturer are not allowed.

    Leave a comment:


  • Han Solo
    replied
    Max Number of Servos when Servos not Used

    Originally posted by FTC5501
    With this years game we need to switch the side some mechanisms are on depending on which alliance we are on. If we have more than the max number of servos on our robot but only the max number are plugged in and active is this legal? When we don't use a certain mechanism we unplug the servo and plug the other servo in.


    A: No. The servo limit applies to all servos on the robot, regardless of their status/use. Servos that are not currently in use still count against the limit.

    Leave a comment:


  • Han Solo
    replied
    Other Vex 2-wire Motors

    Originally posted by FTC5116
    We have some old vex 2-wire 269 motors. Can we use these motors instead of the 393 motors?


    A: No. The Vex 269 motor is not allowed.

    Leave a comment:


  • FTC5116
    replied
    Robot Inspection and Build Rules - Electrical - Answer Thread

    Hello,

    We have some vex 2-wire 269 motors. We were wondering if we could use those or do we have to use the 2-wire 393 motors?

    Leave a comment:


  • Han Solo
    replied
    Voltmeter On Robot

    Originally posted by FTC7330
    We have a follow-up question to the question asked by FTC3620 and replied to in post #2 in "Robot Inspection and Build Rules - Electrical - Answer Thread".

    The question was "Would a digital volt meter be allowed on the robot?".

    Our follow-up question:

    Would a volt meter be allowed if it can only be activated by holding down a button and the button would never be activated in a competition? Such a configuration in our thinking would serve no purpose other than being extra weight during a competition, but would allow us to check the battery between competitions without removing it. Another justification would be electronics that are not connected to electricity aren't really electronics (maybe a broad ruling such as this would be useful for other teams).

    Thanks,
    Team 7330


    A: No. All parts on the robot must be legal, regardless of usage within any given match.

    Leave a comment:


  • Han Solo
    replied
    Using a switch to short motor control wires?

    Originally posted by FTC5628
    Our team has intermittent problems with "back-drive" on our motors used for hanging on the cliff. In the future we'll use worm gears, but for now we have to deal with the back-drive issue. One method that one of the team found during his research was "motor braking" where the terminals of a motor, when shorted together, would cause a motor to stop back-driving (mostly). This led to two designs and questions:

    1 - Once the robot was hanging, the driver would press the controller button that would cause a servo to short the two motor wires together. The servo has a cleverly designed servo horn that will make/break electrical connections. After refinement of the design and with an eye toward potentially saving our fuses, the servo would first break the connection to the motor controller then short the motor wires together. Our read of the rules, particularly <RE02> and <RE05> still left us wondering if this is legal?

    2 - If the answer to #1 is "yes it is legal" - would using a DPDT switch (activated by the servo) also be legal? I would feel much better using a switch than the previous approach.


    A: No. For safety reasons, motors may only be controlled by motor controllers.

    Leave a comment:


  • Han Solo
    replied
    Originally posted by FTC4029
    Hi,

    Is it legal to power multiple servos off two common power wires (like when using a servo Y-cable), but using two separate signal cables to control each servo individually? There seems to be no rules explicitly disallowing this, assuming we use the proper gauge of wire, keep in mind the current capabilities of the controller and wiring, and power/control the setup from the servo controller only.

    Thanks!
    FTC 4029


    A: Yes. <RE05>.g allows for custom made servo control wiring.Care should be taken to ensure good wiring practices (wire gauge and proper insulation)

    Leave a comment:


  • Han Solo
    replied
    Pixy Camera Module?

    Originally posted by FTC7593
    Thanks for the earlier reply related to the Pixy.
    Assuming:
    a) it is the sole device on a DIM;
    b) it draws less than the 150ma DIM maximum current;
    c) it is in this context only an I2C device
    Would the Pixy be a permitted sensor?
    See also http://www.cmucam.org/projects/cmucam5
    Thanks,
    Martin Haeberli
    Mentor, FTC 7593, TigerBots
    A: Assuming all the above can be done without violating any other rules, yes, the Pixy would be a legal sensor

    Leave a comment:

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