Motors and Servos - Answers

[Billie Jean]

Answers to questions about Motors and Servos can be found in this section.

[Broadway Joe]

GoBilda Motors - Update

Q: Are the GoBilda 5202 Series Yellow Jacket motors legal for this season?

A: The 12 V motors from Modern Robotics are legal and teams may place any gearboxes they want onto them. The only place where that becomes an issue is that our software comes with pre-configured motor settings that are used by the closed loop control software to do things like run to a fixed position, or to do run at a specific speed. These settings are based on the motor and gearbox (for example, the NeveRest 40 or the NeveRest 60, which are the same base motor, but with different gearboxes). If a team uses a motor with a gearbox that is different from our pre-configured settings, then they might have to do some "tuning" in the software to optimize the motor performance during closed loop control.
The following motors are pre-configured:

GoBilda 50.9:1 (Planetary)
GoBilda 53:1 (Spur)
GoBilda 26.9:1 (Planetary)
GoBilda 26:1 (Spur)
GoBilda 5.2:1 (Planetary)

It is important for teams to know that there are some potential integration issues that should be considered before deciding whether or not to use them on your robot:[LIST=1][*]The motors have different electrical 12V power connectors from the kind used with our Control System. Teams might need to purchase or make adapter cables to be able to use these motors with their Control System.[*]The encoder cables that are available for these motors have different electrical connectors from the kind used by the REV Expansion Hub. Teams might need to purchase or make adapter cables to use these encoders with a REV Expansion Hub.[*]These motors are not currently available as preset configuration options in the FIRST Tech Challenge software. Teams can select a motor from the options menu that has similar characteristics, but teams might also need to do some additional work (i.e., "tune" motor control coefficients) to optimize the motor behavior.

[Broadway Joe]

Linear Servos

Q: In past seasons, the Actuonix Linear Actuators were legal, for example http://www.andymark.com/product-p/am-3515.htm

Can we purchase and use these linear actuators?

A: These are linear servos and are allowed under Rule <RE10>.

[Broadway Joe]

GoBilda Motor Update

Q: Post #2 of the Motors and Servos Answers thread states "GoBilda Motors are legal for FIRST Tech Challenge competitions." It then lists 5 motor/gearbox combinations as legal.

There are more than 5 combinations of Modern Robotics motors and goBILDA gearboxes that are currently available for purchase, and it is possible that others may made available in the future.

Should Post #2 be interpreted as saying that any other goBILDA gearbox options are not legal? If so, can you clarify why, given that RM02 explicitly permits the use of arbitrary single speed gearboxes and that FTC teams have used Banebots and Vex standalone gearboxes combined with other motors without issue in previous years?

If other goBILDA motor/ gearbox combinations are not legal, can teams integrate goBILDA gearboxes on any arbitrary motor in the same way that they can with Banebots and Vex gearboxes? If not, can you clarify how teams may determine what is a gearbox that is legal to use and what is a gearbox that is not legal to use?

A: Thank you for pointing out the inconsistency in the original post. That Post has been updated to include as legal all 12V GoBilda motors with any gearbox ratio. The list of "legal" motor/gearbox combinations should have stated that these are the only motors that are pre-configured in the software. That has been corrected.

[Pierluigi Collina]

Subject: VEX Motor Configuration

Question: Can we plug 2 Vex 393 motors into one 29 controller?

Answer: No.<RE10> explicitly requires a Vex Motor Controller 29 for each VEX EDR 393 motor

[Pierluigi Collina]

Subject: Painting Motors

Can we paint the motors?
Neverest, Tetrix 12v, Matrix 12v

Answer: <RM04> allows painting of raw materials and COTS parts. While there is nothing in the rules that explicitly disallows painting motors, there are a couple of things to consider:

• the metal housing is part of the heat dissipation mechanism for the motor
• paint flaking off and leaving residue on the playing field (<RG01>.h)
• characteristics and off-gassing of paint when heated (<RG01>.c)

[Pierluigi Collina]

Subject: Servo Voltage Ranges

Question: As per Game manual <RE10> "Servos may be rotary or linear but are limited to 6V or less and must have the three-wire servo connector."
Does that make the use of REV Robotics Smart Servo and Hitec Servo HSR-2645CRH illegal? We started late last year as a rookie team and I saw teams extensive use these two servos. Can some please explain and/or clarify. I have voluteered as a Robot Inspector this year and want to be very well prepared for the role.

http://www.revrobotics.com/rev-41-1097/

https://www.servocity.com/hsr-2645crh-servo

Thanks for all your help.

Answer: Yes. Both are 6v nominal servos. All servos are typically specificed with a a range of tolerated supply voltages. Both you included are designed for 6v nominal use.

[Pierluigi Collina]

Subject: Servo Modification

Question: Is the modification of servos to be continuous rotation legal, or does that violate RE12?

Answer: Modification of a servo to convert it into a continuous rotation servo is not allowed per <RE15>

[Pierluigi Collina]

Rule

Subject:Servo power consumption

Question: <RE10> Servos says:

"Teams should be prepared during Robot inspection to show documentation confirming that the servos individually and together on the same servo controller do not exceed the manufacturer specifications for the controller."

Consider the following scenarios:

1. A single VEX EDR 393 motor is connected to the REV Servo Power Module, together with other servos connected to the same module
2. A single VEX EDR 393 motor is connected to the MR Core Servo Controller, together with other servos connected to the same controller

What wattage value do teams document for the VEX EDR 393 in the above scenarios?

Answer: Since the robot construction rules limit use of the VEX EDR motors to no more than two per MR Core Servo Controller or REV Servo Power Module, a reasonable approach would be to derate the current capacity of the modules by 50% for the purposes of determining other servos that can be attached/controlled.

[Pierluigi Collina]

Subject: New Motors?

Question: AndyMark is out of stock of the usual Neverest classics and when they do come back in stock will ship from Sydney Australia. Are the Neverest Sport legal for FTC?

Rev is out of stock of their HD motors with nothing expected within the next month.

That leaves only the goBilda (Matrix) motors. Unfortunately, these motors are not compatible with ANY of our current building systems thus causing ripple effects with the robot construction when you need to replace a motor.

I respectfully request that the Game Committee consider approving other DC motors as FTC appears to be clearning out the market for all legal motors. Having to mix and match non-compatible motors throughout the season is really a problem. Please consider expanding the legal motor list so there are more options and, therefore, more in-stock options that won't require robot revamping just because a motor needs to be replaced.

Answer: The Neverest Sport is a gearbox, not a motor. We revisit the list of motors allowed annually, but not during mid-season.

[Pierluigi Collina]

Subject: Allowed Servo

Q: Is this servo from amazon legal? We don't see anything illegal about it as per guidelines in Game Manual 1.

https://www.amazon.com/dp/B07GK1G5FV...1-d1277253676c

A: We cannot possibly rule on the legality of every individual servo! A servo is allowed if it is compatible with an allowed servo controller, operates at 6v and has a standard 3-wire connector. Take care to observe total current capacity of the servos and the servo controllers that are used to drive them.

[Pierluigi Collina]

Subject: Servocity Mot

Q: Is this motor from Servocity legal for FTC?

1,621 RPM HD Premium Planetary Gear Motor w/Encoder

https://www.servocity.com/1621-rpm-hd-premium-planetary-gear-motor-w-encoder

The specifications look similar to gobuilda planetary gear motor and Anymak Orbital motor.

A: No. Only the motor listed in part 1 of the game manual are allowed.

[Broadway Joe]

[QUOTE=FTC11525;n73070]I
Servocity Motor

Q: Is a Servocity premium planetary gear motor legal? See https://www.servocity.com/195-rpm-pr...ary-gear-motor [/QUOTE]


A: No, this motor is not on the list of approved motors. See Rule RE09