Commerical Off the Shelf Components - Answers

[JoAnn]

Answers to questions about Commercial Off the Shelf Components (COTS) can be found here.

[Buzz]

Question 1: Is the gripper kit from ServoCity legal to use?

https://www.servocity.com/standard-gripper-kit-b

Question 2: What if we redesign the claw and 3D print, but reuse the servo bracket in the kit, is the modified module legal?

Answer 1: The referenced gripper kit from ServoCity is not allowed. Commercial off the shelf gripper kits are specifically called out as illegal in the Game Manual Part 1, rule <RM02>.

Answer 2: In general, it is legal to remove a single degree of freedom part from a commercial off the shelf multiple degree of freedom mechanism and use the single degree of freedom part in a Robot.

It is legal to use the servo bracket (flat plate with through-holes) from the ServoCity gripper kit in a Robot. It is also legal to add Team designed and fabricated parts to the servo bracket to build a gripper or other mechanism. However, it is against the spirt of rule <RM02> to use the servo bracket and make copies or slightly modified versions of the remaining unused gripper kit parts and build a gripper for the Robot.

[Ming the Merciless]

Subject: VEX Linear Slides
Q: Can we use VEX linear slides?
https://www.vexrobotics.com/276-1926.html

A: Yes, the VEX linear slide kit is a legal COTS part.

[Ming the Merciless]

Subject: Single Degree Of Freedom

Q: The rule: <RM02> Commercial Off The Shelf Parts - Teams may use Commercial Off The Shelf (COTS) mechanical parts that have a single degree of freedom. A single degree of freedom is a system whose motion is defined just by a single independent co-ordinate.

1 Does this only apply to COTS or does it apply to anything the team uses.(3D printed and designed by the team)

2 If the team would like to design and build a robot arm, with two segments with a hand grabber at the end (maybe even have fingers with joints), is that considered a single degree of freedom because they are separate but connected at the elbow and wrist joint with a servo?

Thanks

A1: Rule <RM02> refers only to COTS parts. Teams may design and build mechanisms with as many degrees of freedom as they wish.

A2: A team designed and built robot arm as described is a legal mechanism.

[Ming the Merciless]

Subject: Servocity Cascading X-Rail Slide Kit

Q: Is this a legal COTS part? https://www.servocity.com/cascading-x-rail-slide-kit

A: Yes, this is a legal COTS part.

[Ming the Merciless]

Subject: Mirrors

Q: Rules restrict directed outbound light (lasers and LEDs with mirrors). We were wondering...
Can we use a mirrored surface as part of the incoming light path for the phone camera?

A: Rule <RE12> disallows the use of mirrors for directing robot based light sources. Mirrors used to direct an image to the camera in the robot controller are allowed.

[Ming the Merciless]

Subject: Servocity Gearbox with Potentiometer
Q: <RM02> states that Examples of allowed single degree of freedom parts Single speed (non-shifting) Gearboxes.

Are the ServoCity pre-assembled servo gear boxes legal, given that they include an external potentiometer (see for instance https://www.servocity.com/cm-785hb-s...earbox#198=8)? They are pre-assembled, and seem like nothing more than en enlarged form of the standard internal servo gearbox.

A: Yes, these gearboxes are a legal COTS part. However, the potentiometer is still subject to all the other rules regarding electrical devices and sensors.

[Ming the Merciless]

Subject: Casters

Q: Do either or both of these violate the intent of the rules on freedom of motion on purchased hardware? IE too many degrees of freedom? There are differences of opinion on the intent of the build rules on our team...

https://www.harborfreight.com/1-inch...ing-67060.html

https://www.harborfreight.com/materi...ter-90997.html

A: The ball caster is a legal COTS. However, the caster wheel has more than one degree of freedom and therefore it is an illegal COTS part.

[Ming the Merciless]

Subject: Brake Cable

Q:Can we use bike-brake cable to control the movement of our linear slide? something like https://www.amazon.com/Shimano-Unive.../dp/B0050LUBZ8

A: Yes, brake cable is a legal COTS part.

[Ming the Merciless]

Subject: Cable Drag Chain

Q: We would like to use a cable drag chain to manage our wiring and cannot decide if it is allowed. Here is an example of the part that we would like to use:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Thanks!

A: Yes, this is a legal COTS part.

[Ming the Merciless]

Subject: Linear Actuator

Q: My team needs to know if the Misumi LX-26 linear actuator is allowed. It has no motor, no sensors. We were given the bare actuator and have created a mount plate for an AndyMark Neverest motor. It is readily available for purchase from Misumi online catalog as well as eBay.

https://us.misumi-ec.com/vona2/detai...075270/?Inch=0

A: The linear actuator without the motor (essentially a leadscrew) is a legal COTS.

[Ming the Merciless]

Subject: Pan/Tilt Servo

Q: IsPan/Tilt Servo Motor Kit for Pixy (CMUcam5) - 2 Axis Robotic Camera Mount https://www.amazon.com/Tilt-Servo-Mo...J37TR8S48KJMNZ
allowed? it comes unassembled with mechanical parts and two servos.

A: This is a COTS device with more than one degree of freedom. Rule <RM02> states that "Purchased mechanism kits (for example, grippers) that violate the single degree of freedom rule, either assembled or requiring assembly, are not allowed". Therefore this device is not allowed.

[Ming the Merciless]

Subject: Eccentric Mechanism

Would a commercial off the shelf part that has an eccentric mechanism be classified as having a single degree of freedom?The specific part is

https://www.sparkfun.com/products/10398

We know the pump cannot be used as is since it includes an illegal DC motor. The team members disassembled the pump and inspected the parts and how it works. They observed that the main component is an eccentric mechanism attached to the motor shaft so that as it revolves, it moves a plastic part back and forth a little bit causing the pump action. Other parts look to be diaphrams that help move the air around.

A: A simple eccentric mechanism is allowed under the COTS rule. However the entire pump must still meet the requirement that there be no pressure buildup during operation of the vacuum pump. From the website it is impossible to tell if this requirement is being met. The Robot Inspector at your event will be able to determine this after a close visual inspection.