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Robot Inspection and Build Rules - Electrical - Answer Thread

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  • Buckaroo Banzai
    replied
    Servo Stall Current Limits

    Originally posted by FTC8907
    Just a quick question to clarify what the limits are on the servos we are allowed to use.

    <RE04> states that the servos are limited to 12 in number and that any compatible servos are allowed barring the fact that they don't overload the servo controller. But then on this document posted: http://www.firstinspires.org/sites/d...parts-list.pdf it states clearly that all servos must be rated at 800mA or less.

    Can you please clarify? Thank you


    A: As long as the servo is compatible with the servo controller and the total stall current for all servos controlled by a single controller does not exceed 5 amps the servo is allowed.

    Leave a comment:


  • Buckaroo Banzai
    replied
    Servo Current Limits

    Originally posted by FTC8045
    We don't see limits for servo Amperage in the Game manual, but do note that the MR modules are only rated for 1.5A per servo and that according to ServoCity, the stall current for quarterscale servos is 1.8A and the popular 645MG servos is 1.6A. We're not sure this poses a real safety problem, but would like to confirm that the use of quarterscale servos and the 645MG servos are legal even though the specs on the servo controller say we shouldn't be using them.


    A: This question has already been addressed. Please see post #9 under the Robot Inspection and build Rules - Electrical - Answer thread.

    Leave a comment:


  • Buckaroo Banzai
    replied
    Wiring Conventions/Coloring

    Originally posted by FTC8681
    Rule <RE05>.h states:
    "Power and motor control wires must use consistent color coding with different colors used for the Positive (red, white, brown, or black with a stripe) and Negative/Common (black or blue) wires."

    It specifically states for "power and motor control". If we use extension wires for sensors (analog and i2c), does the "consistent color coding" portion of the above statement also apply? For example, if a sensor is soldered with 4 colored wires, and a 4 wire extension that has 4 different colors extends the connection to the DIM controller, is that legal?

    Thanks....


    A: Yes. In your example, the wires you are extending include power/ground and have a color convention that denotes power/ground vs. signal. Care should be taken to match the convention. The colors used in your extensions do not need to be identical to the wiring that is being extended, but should be clearly identifiable and the same color convention you use should be applied consistently to all extensions.

    Leave a comment:


  • Buckaroo Banzai
    replied
    Vendor Battery for LED Strip

    Originally posted by FTC6081
    According to Rule <RE03> :
    "Approved light sources may include an internal (as supplied by the manufacturer) battery. "

    Would this battery pack be considered an internal battery? It's an LED strip with an internal battery holder which holds three AA batteries.

    http://www.amazon.com/TEQIN-Waterpro...s=led+strip+aa

    Team 6081 i²r robotics


    A: Yes. The above product is an example of a vendor supplied battery for LED's as allowed by <RE03>.g

    Leave a comment:


  • Buckaroo Banzai
    replied
    Red Dot Scopes Allowed?

    Originally posted by FTC4997
    Post #118 of the Mechanical thread (http://ftcforum.usfirst.org/showthre...ll=1#post26298) states that the mentioned red dot scopes are illegal because they are not powered by the main robot battery. However, it does not say anything about the legality of them. Would a red dot scope (NOT a laser) that is powered by the main robot battery be legal? Thanks!


    A: "Red Dot" scopes are not legal. Focused light sources are disallowed by <R06>.a

    Leave a comment:


  • Buckaroo Banzai
    replied
    I2C I/O expanders?

    Originally posted by FTC5206
    Hi, we were wondering if the following type of device is legal per forum ruling #51, which explicitly allows an i2c multiplexer like this: https://www.adafruit.com/products/2717
    Are either of these (https://www.adafruit.com/products/593, or https://www.adafruit.com/products/292) similar devices which expand an i2c port allowed to be connected to the CDIM in order to get more digital type pins?

    Thanks,
    FTC 5206, The Knights of Ni
    A: No. The I2C multiplexor option was allowed to take care of the case where sensors have non-changeable i2c addresses. The allowance permits using multiple sensors of the same type.

    The chips/boards referenced above are general purpose I/O expanders and fall under the category of "other electronics" and are prohibited by <RE06>.d

    Leave a comment:


  • Buckaroo Banzai
    replied
    Mixing/Matching 12v DC Motors with Motor Controllers

    Originally posted by FTC10877
    Hello FIRST,

    To clarify our previous question, we are using a Legacy Matrix system with a single 9.6V battery, two Matrix motor/servo controllers, and three Matrix 9.6V motors. We have been unable to source additional Matrix motors from Modern Robotics Inc., of any sort, and so we would like to use two or three of the AndyMark NeveRest (20,40,60) series of motors, with our Matrix module to drive additional mechanisms. We do not want to waste our money buying motors we cannot use, so we have not finished some of our mechanisms. The motors are rated at 12V, but we have heard from another team that they work fine on 9.6V - they simply run slower than they would at 12V, with no risk of damaging them. Is using NeveRest motors with the 9.6V Legacy a legal configuration?

    Thank you.


    A: After getting input from the manufacturers, 12v motors (of any of the allowed types) can be used with any of the Motor Controllers (Matrix, Legacy HiTechnic, Modern Robotics). Please note that the motor connectors may need to be changed. Care should be taken to fully understand the connections before modifying the motor connectors to minimize the chance of damage to the motors or controllers.

    Teams should also be aware that the encoders that are built into several of the motors produce different counts per revolution and will likely make using the built-in PID control functionality difficult.

    Leave a comment:


  • Buckaroo Banzai
    replied
    USB Surge Protectors

    Originally posted by FTC6081
    As winter has arrived with drier air, we are seeing many robots experience static electricity discharges. Last year FIRST recommended installing a USB surge suppressor from l-com http://www.l-com.com/surge-protector...el-mount-style between the NXT and Samantha. We did this, and it seemed to help. Would this part be legal this year to install in the cable between the phone and the Power Distribution Module? If so we'll do some testing.

    FTC 6081 i²r robotics


    A: USB Surge Protectors are explicitly allowed by <RE05>.a

    Leave a comment:


  • Buckaroo Banzai
    replied
    LED's powered by Servo Controller Ports

    Originally posted by FTC8681
    We want to use a string of 6V LED Lights on our robot:
    http://www.amazon.com/gp/product/B01...rch_detailpage

    We wish to remove the battery and add the wire to the robot so it can be controlled in the program. It would still serve no functional purpose to the robot other than decoration.

    According to rule <RE03> g:
    "Approved light sources may include an internal (as supplied by the manufacturer) battery. Additional approved power sources are the use of a power port on the Core Power Distribution Module, a motor-control port on the Core Motor Controller Module, or a motor controller port on the Legacy HiTechnic Motor Controller."

    Can we use a servo-control port on the Core Servo Controller Module instead? The rule implies that there are other approved power sources not listed.

    In addition, if we were to use the supplied battery pack to power the LED strip and signaled the LED strip independently with the Core Servo Controller Module, would it be legal?

    Thanks!


    A1: No. LED's may not be connected to or powered by Servo Control Ports of any module.

    A2: Without additional description, it is not possible to determine what "signaled the LED strip independently" means or whether the would be allowed under current rules.

    Leave a comment:


  • Buckaroo Banzai
    replied
    DC Computer Fan as Motor?

    Originally posted by FTC9921
    We want to use a 12V DC Computer Fan to blow away the debris.
    If it is allowed, when the fan is plugged into the motor controller, does that count as a motor?


    A: No. A 12V DC Computer Fan is not an allowed DC motor and may not be used on a robot.

    Leave a comment:


  • Buckaroo Banzai
    replied
    Robot Motion During Initialization

    Originally posted by FTC9794
    Hello,

    Our team has a rack and pinion on our robot powered by a DC Motor. When the rack and pinion is all the way in, it presses a touch sensor. During the initialization of autonomous, is it legal to move the rack and pinion in all the way until it presses the touch sensor?

    Thank you,
    Team 9794
    Wizards.exe


    A: Yes. This type of initialization motion is allowed. Be sure to add a sticker warning of robot motion during initialization (see the game manual)

    Leave a comment:


  • Buckaroo Banzai
    replied
    External Battery Pack for LED's

    Originally posted by FTC5250
    We would like to have a strip of LEDs on our robot for decoration.
    http://www.amazon.com/FAVOLCANO-Flex...308057&sr=8-29

    According to rule <RE03> :
    "Approved light sources may include an internal (as supplied by the manufacturer) battery. Additional
    approved power sources are the use of a power port on the Core Power Distribution Module, a motor control
    port on the Core Motor Controller Module, or a motor controller port on the Legacy HiTechnic
    Motor Controller. "

    We do not want to power it from our main battery through the Core Power Distribution Module because of the drain it would cause on the battery. Last year we hooked the lights to a separate 9v battery. The rule says that the lights may be powered by an internal (as supplied by the manufacturer) battery. These lights do not have one and are meant to be powered by a separate battery. We would like to confirm that this is still legal.


    A: No. <RE03> lists the allowed power sources. An external battery pack is not a listed source and is not allowed.

    Leave a comment:


  • Buckaroo Banzai
    replied
    Solenoid Legal?

    Originally posted by FTC9761
    Is a 12v solenoid legal?

    http://www.jameco.com/1/1/28077-smo-...-solenoid.html

    They're single axis.

    Thanks


    A: No. While it is true that a solenoid is a 1 degree of freedom assembly, it is also an electrical part. <RE06>.d disallows all other electronics (including solenoids)

    Leave a comment:


  • Buckaroo Banzai
    replied
    &lt;RG02&gt; and Static Dissipation Chain?

    Originally posted by FTC6389
    Are we allowed to drag a copper chain attached to our robot chassis to the floor? We are having horrible static problems. When the robot touches another robot, or the ramp, or the field walls, our robot dies immediately. We have taken all other precautions with regard to separation of power and control wires, stain relieving the USB connectors, etc. We have proven through testing that the ESD event is in fact the problem.

    thanks

    - The Lazybotts


    A: No. Rule <RG02>.i prohibits mechanisms or components that are designed to ground the Robot frame to the Playing Field.

    Leave a comment:


  • Buckaroo Banzai
    replied
    LED's &amp; Decorative Items

    Originally posted by FTC0516
    Hello, we have a few questions concerning nonfunctional decoration items.

    First, regarding LED lighting. We are interested in using some LED strips (example: http://www.amazon.com/Lumcrissy-Flex...trip+purple+5m) however, this item lacks a manufacture created power source. Is it acceptable to create a safe power supply (within specifications for the LEDs) for the system, as none was provided?

    Our second question regards a GoPro (specifically, the mounting). When attached, is the GoPro (all WiFi capabilities disabled) required to fit within the 18" cube sizing constraint? It's sole purpose is to provide post match entertainment and mounting the camera higher would protect it from robot contact and offer a better viewing angle.

    Thank you,
    Team 516


    A1: LED's may be powered as listed in <RE03>.g only. A custom made power supply is not allowed.

    A2: Decorations are part of the robot and are subject to the sizing limits of the robot. The camera would need to fit inside the 18" cube.

    Leave a comment:

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