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Official Q&A: VEX U Robotics Competition 2024-2025: High Stakes

Usage Guidelines All Questions

2525: Clarification on Commercially Available Pneumatic Solenoids

QUEEN
11-Feb-2025

<VUR13> point (e) states that

If commercially available 12V solenoids are used, these are considered Additional Electronics and must therefore satisfy all conditions listed in <VUR12>. 12V solenoids may be either powered by an additional power source (per <VUR12c>), or by a 5V-12V step-up converter from the V5 Robot Brain. If an external power source (or other Additional Electronics device) is used to interface with the solenoid, Teams MUST be able to demonstrate that there is no way for the solenoid to receive power while the Robot is receiving a Disabled state from the field controller

We would like to clarify some of the meaning and intent of this rule.

  1. The second sentence seems to prohibit 12V solenoids from being powered from the V5 Robot Brain via the power rail in a smart port (possibly using a voltage converter), which is typically 12-14V, which seems somewhat arbitrary. Is this the intention of the rule?
  2. Does the third sentence apply to only 12V solenoids, or to all solenoids?
  3. Is the intention of the third statement that all applicable solenoids are forced into their "default" state when the robot is in disabled, or that their state is not changed while the robot is in disabled? Or is either behaviour acceptable?
  4. What is sufficient documentation/demonstration for proving compliance with the third sentence? Note in connection with question 2: if this means that it is impossible for user code on the robot brain to actuate the solenoid, for example, then this rule is not respected by solenoids which are directly controlled by 3-wire ADI ports (regardless where they receive power from, as vexOS permits digital outputs to be changed while the competition state is disabled).
Answered by committee
14-Feb-2025
  1. Yes, this is the intention of the rule.
  2. The third sentence would apply to all commercially available solenoids.
  3. The intent of the third statement is to make sure that in a disabled state, the solenoid cannot be activated and/or change states.
  4. It should be demonstrated in inspection that the solenoid cannot activate or change states while the robot is disabled, regardless of any controller or sensor input. Basically, the intent is to ensure that when disabled, it is not possible for the system to be able to change states, move cylinders, actuate, etc. Your program should be written such that it requires an enabled state in order for the solenoid to actuate or change states. This is meant to coincide with clause C of <SG1> (Robots remain stationary at the beginning of the match) and <S1>.