Control System - Answer Thread

[Administrator]

Answers to questions posted pertaining to the Control System.

[Pierluigi Collina]

USB Hubs on Robot

Hello, I'm from team 3491 FIXIT,
We are wondering if it would be legal to plug a non-powered USB into the Core Power Module. The power module only has room for 7 USB devices and it is quite likely we will need eight modules this year.

Last year we had 1 Core Device interface
3 Motor Controllers
3 Servo Controllers - We understand that the there are 6 servo ports for 12 servos, but if you use any servo that is more powerful that the HS-422 there is too much power used and the servo controller shuts off. We had to split into three controllers to avoid this issue.

This year we are considering using a mecanum drive so we will need a fourth motor controller. The only way to achieve this would be to add a splitter to the power module.

Thanks Team 3491

Answer: <RE14>.d explicitly allows stand-alone USB hubs to be used on robots (both powered and unpowered). Powered USB hubs need to be compatible with the 12v power that is available on the robot.

[Pierluigi Collina]

Cracked Phone Screens

Can you give some guidance regarding the use of phones with cracked screens in competition?

Answer: As long as the cracked screen does not:

• present a safety hazard
• render the screen unreadable by field personel

The phone can be used with a cracked screen

[Pierluigi Collina]

Acceptable Alternative Robot Initialization Sequence

Section 1.5.1: After placing their Robot on the Playing Field, the Drive Team selects their Autonomous Period Operational
Mode (Op Mode) on their Driver Station Android device and initializes their Robot by triggering the Team’s
initialization event software.

Is this order strictly enforced? May a team initialize the robot prior during the process of placing it? For example, we are considering having a touch sensor configured to indicate to the software what color the robot is. So we would place the robot, initialize the software, and then touch the sensor if the robot was blue. Is this allowed?

Thanks.

Answer: The method you have described is compatible with the description in Section 1.5.1. You should take care to make sure that your setup and initialization is done in a timely manner. Field personnel (Referees and/or FTAs) will likely NOT allow you back onto the field to take care of pressing your sensor if you forget before leaving the field.

[Pierluigi Collina]

Modifying FTC Driver Station App

Is it legal to make changes to the FTC Driver Station App?

Answer: NO. No modifications to the FTC Driver Station app are allowed.

[Pierluigi Collina]

Fully Custom Hub

Greetings, rules people:

<RE14> (d) says "Stand-alone USB hubs are allowed."
<RE17> Says "Electronic devices that are not specifically addressed in preceding rules are not allowed : partial list includes... . and custom circuits."

So, how about a custom stand-alone USB hub?

Our teams are frustrated with the mechanical design of the motor controllers (as I'm sure many of us are). Having large wires exit from each controller along 3 of the controller's planes is really annoying in an 18" robot. USB cables and connectors are huge, connectors fail easily.

To make wiring simpler, it occurred to us that we could mount the motor controllers on top of one another in a tight stack, like the plug-in cards of the old FRC cRIO. The stack arrangement was popular in the old NXT/Hitechnic system.

- Would it be within the rules to fabricate a custom stand-alone USB hub that would form a "backplane" that the motor controllers fit into? This creates a mechanically stable connection to the motor controller and requires no modifications to any Modern Robotics parts. The custom hub would be plugged into the PDC.

- If a custom-built hub is not permitted, could a small COTS hub be modified (removed from its enclosure, connectors removed and short wires soldered on) for this purpose?

Modifying a COTS hub may violate <RE15> though, especially if connectors are removed. Moving a COTS hub from its supplied enclosure to a new one appears to be within the scope of <RE15>

A custom hub will not provide any robot performance advantage over a COTS one, the purpose of constructing it is purely for mechanical compactness and electrical stability.

Answer: A fully custom hub would not be allowed as it would fall under the definitions of "Additional Electronics" and <RE17>. Applying <RE15> as it is written would allow for modification of a hub that did not have connectors mounted to the circuit boards, but had an "octopus" type of wired fan-out. (i.e. Replacing or adding connectors on wires ...)

[Pierluigi Collina]

Limits on Core Legacy Modules vs. Legacy TETRIX Motor/Servo Controllers

Question 1: Do Robot Rules RE07 and RE08 limit the quantity of Legacy Tetrix motor/servo controllers?

<RE07> Control Module Quantities - Robot control module quantities are constrained as follows:

1. Exactly one (1) Core Power Distribution Module is required.
2. No more than two (2) Core Device Interface Modules are allowed.
3. No more than two (2) Core Legacy Modules are allowed.
4. Any quantity of Core Motor and Core Servo Controllers are allowed.
5. No more than two (2) Legacy MATRIX DC Motor/Servo Controllers (unified module) are allowed.

<RE08> Motor and Servo Controllers - Motor and Servo Controllers are allowed in only one of the following two configurations (cannot mix configurations).

1. Core Motor Controllers, Core Servo Controllers, Legacy TETRIX DC Motor Controllers, and Legacy TETRIX Servo Controllers in any combination.
2. Legacy MATRIX DC Motor/Servo Controllers (unified module).

Question 2: If this was the intent of rule RE07.5 , why hasn't the wording been changed in Game Manual Part 1 or on the Robot Inspection Checklist?

Question 3: How are teams supposed to know that this is the intent?

Please clarify.
Thank you!

Answer 1: <RE07> does not expressly limit the number of Legacy TETRIX Motor or Legacy TETRIX Servo Controllers. <RE08> does not limit quantities, it constrains the types of controller configurations allowed.

The Robot Inspection Checklist does not state a limit for Motor controllers or Servo controllers (either Modern Robotics Core or TETRIX)

Answer 2: <RE07>.e is a limit on the Legacy MATRIX Motor/Servo Controller (unified module) and makes no mention of Legacy TETRIX controllers

Answer 3: Teams should read/understand the game manuals

[Pierluigi Collina]

Other Gamepad Controllers?

Are we restricted to only Xbox controller #52A-00004, or can we use any Xbox 360 controller. For example: https://www.amazon.com/gp/aw/d/B00EZ...xbox+360+wired

Answer: the only allowed controllers are the two listed in <RE16> Driver Station Contraints

• Logitech F310 (Part# 940-00010)
• Xbox 360 Controller for Windows (Part# 52A-00004)

[Pierluigi Collina]

Tablet Computer in Driver Station

Is a wifi-disabled tablet allowed in the driver's station area?
It would be used for data entry and data analyses during a game.

Team #11115 - Gluten Free

Answer: No. Rule <G1> provides clear guidance that any device that may be mistaken by a casual observer to be a electronic communication device is not allowed.

[Pierluigi Collina]

Motor Controllers

Are the motor and servo controllers from last year still legal?

Answer: Yes.

[Pierluigi Collina]

Out of Band Communication between Robot Controller and Driver Station

Hi,

1. Can we run a Service (that we created) on the Driver Station phone that is completely separate from the FTC Driver Station app during a tournament match?
2. If so, can we set-up a socket connection between the Service and the Robot Controller app (by creating DatagramSocket objects in both applications)?
3. If so, can we transmit messages from the Robot Controller phone and the Driver Station phone and have the Driver Station phone read the messages aloud (via the TextToSpeech object)?

We want to do this because, during a match, our drivers/field coach are focused on the game in front of them. When, for example, a ball is collected by the robot on the far side of the field (so we can't see it), Telemetry doesn't effectively notify us about it. If we had the Driver Station phone speak the message out loud, we'd know that a ball has been collected very quickly.

To be clear, we have not modified the FTC Driver Station app nor the FTC Robot Controller's Wifi Direct Connection. We've merely created a second socket connection.

Thanks,
FIX IT 3491

Answer 1: No. Communication between the robot and driver station is only allowed via the robot controller and driver station applications.
Answer 2: n/a
Answer 3: n/a

[Pierluigi Collina]

Holding Driver Station Phone during Teleoperated Period

Is the drive team allowed to hold the driver station phone and USB hub during the teleoperated period?

Answer: Yes. There is nothing in the rules that prohibits members of the drive team from holding the driver station phone during the driver controlled period.