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Things we learned and useful other info / Volume of pneumatic cylinders
« Last post by Louis L on January 25, 2019, 12:51:15 PM »
I've calculated the volume of the cylinders we have in our inventory. This is useful when you want to look at how much air is used vs. how much air you have in your accumulators. Volume is in cubic inches and milliliters.

The Clippard accumulators are 574 mL in volume.
The high pressure side is 120 psi max.
The low (operating) pressure side is 60 psi max.

Length (in) Bore (in) volume (cu in) volume (mL)
2 3/4 0.88 14.42
4 3/4 1.76 28.84
5 3/4 2.21 36.22
6 3/4 2.65 43.43
12 3/4 5.30 86.85
6 1 1/16 5.32 87.18
8 1 1/16 7.09 116.18
2.5 1 1/2 4.22 69.15
8 1 1/2 13.5 221.23
4 2 12.57 205.99
Things we learned and useful other info / Useful info from Bimba for using pneumatics
« Last post by Louis L on January 11, 2019, 01:43:06 PM »
I pulled two Technical Tips from the Bimba web site ( Bimba is a sponsor of FIRST. These are useful for anyone starting out with using pneumatics.

(1) How to Determine the Right-sized Cylinder for Your Job

"Specifying the right cylinder for the right job results in better and longer cylinder performance. And that means lower overall operating costs. Proper cylinder size selection begins by calculating 1) the weight of the load, 2) the required velocity, and 3) the air pressure used. Let’s take a closer look at each of these three factors.
Weight of the load:
This is set by the machine design. In order to move the load, you’ll obviously need a cylinder that pro-vides force
greater than the load. We recommend allowing an additional factor of 25% force over the load to compensate for friction.
Velocity:Velocity is also usually set by machine design, but there’s usually some latitude within a range. Low speeds (up to 4 in/sec) require 25% more force than the load, moderate speeds (4 to 16 in/sec) about 50% more and high speeds (greater than 16 in/sec) about twice as much.
Air pressure:You need consistent air flow at the minimum effective pressure to maintain the desired velocity. Operating the cylinder at too high a pressure accelerates seal wear and creates stress on the cylinder. Inconsistent pressure can cause system malfunction or failure.

Next you’ll need to determine bore size. Let’s look at an example assuming a maximum load of 100 lbs, a minimum velocity of 8 in/sec and a minimum pressure of 60 psi. The velocity is moderate, but the force should be about 50% greater than the load, or 150 lbs. Dividing the force (150) by the pressure (60) gives you a power factor of 2.5. A 2” bore cylinder, with a power factor of 3.1, provides the needed force.
You’ll also have to consider stroke length, spring force and overall dimensions of the space. But this is only the start."

(2) Power Factors
Rather than copying and pasting the contents of the table in their Technical Tips, I'm attaching the entire PDF file. Please refer to its contents.
  • For our uses, look at the first set of columns under "ORIGINAL LINE".
  • The Bore Size is the left-most column. This is the diameter of the cylinder bore in inches.
  • The Power Factor is a multiplier you use to determine what you need. Do the math and you'll see that it's really just the surface area of the bore in square inches. Extend and Retract are asymmetric because the piston rod takes up space and reduces the surface area of the bore.
  • We'll most likely be operating at 60 PSI so use the FORCE(#) values in that column. Do more math and you'll see that this is just 60 times the POWER FACTOR. If we end up using less than 60 PSI, it's easy to calculate the new numbers.
The numbers in this table apply not just to Bimba. We have and will order from other manufacturers as well and all of this still applies. As the PDF notes, this is just for reference but it'll get you close. The rest is up to you :)

Wiring needs to be controlled. Sometimes the priorities can be confusing as they seem to contradict each other.
  • Keep wiring neat. The more the mess, the greater chance of problems.
  • Have service loops, slack in the cables. This allows plugging and unplugging of cables.
  • Strain relief at connections prevents cables from coming off when a cable gets pulled.
  • Hot glue on connector can be used if the connector feels loose - be careful how it's used.
  • Route cable such that it does not pop off. This usually means folding the cable over 180 degrees and zip tying it down.
  • Check for pinch points.
Robot Software / Re: User Interface
« Last post by Louis L on October 17, 2018, 01:04:45 PM »
Updated to reflect climber function UI
Imagery / PacMan costume
« Last post by Louis L on August 20, 2018, 09:42:22 PM »
Ran across this drawing Michele made; thought we could archive it here!
General Topics / Planet naming contest
« Last post by Louis L on July 22, 2018, 10:09:54 PM »
Use this thread to suggest names for the planet. Rules are below. We'll collect names until Monday Aug 6. Here are the rules:


DESTINATION: DEEP SPACE Presented By The Boeing Company brings us to a planet in deep space that is as mysterious as it is inhospitable. This lifeless planet presents many challenges: Its atmosphere is toxic, its ever-changing landscape is dangerous and unpredictable, and…it has no name. Would you like to name it? Now is your team's chance to influence our story and be forever known as the team that gave our planet its name!
The FIRST Robotics Competition 2019 “Name the Planet" Contest is open to all past FIRST Robotics Competition teams with plans on returning during the 2019 FIRST Robotics Competition season, as well as all rookie teams for the 2019 FIRST Robotics Competition season. Only ONE submission is allowed per team, and must be submitted by the Lead Coach/Mentor 1 or 2 as designated within the Team Dashboard. If your team does not yet have a permanent team number, please use your assigned temporary team number. Submissions must be complete by 11:59PM EDT on Wednesday, August 15, 2018 to be considered.

Name the Planet Contest rules:

(1) No submissions may contain material protected by intellectual property laws, including, by way of example, and not as limitation, copyright or trademark laws (or by rights of privacy or publicity) unless you own or control the rights thereto or have received all necessary consents to do the same. For example, “Disneyland” is not an appropriate name.

(2) The Planet Name will represent your team and FIRST, and it must be designed in the spirit of FIRST Core Values.

(3) The Planet Name should be written using characters in the modern Latin alphabet not exceeding 50 characters (including spaces).

(4) It is important that we know the correct pronunciation of your planet name. Although the pronunciation of many names is obvious, some require special attention. The pronunciation guide is a way to help us pronounce your planet name correctly. The pronunciation guide should be written for English language speakers. For example, “Raul Gonzalez” would have a pronunciation guide similar to “rah-OOL gon-SAH-les”. It’s recommended to use a pronunciation resource such as the following document in creating your pronunciation guide:

By submitting your entry into this survey, you irrevocably grant to FIRST and its assigns, licensees, and successors the right to use your submitted Planet Name in all forms and media including composite or modified representations for all purposes, including advertising, trade, or any commercial purpose throughout the universe and in perpetuity. You also waive the right to inspect or approve the use of the Planet Name for publication or other written copy used in connection with the Planet Name.

Please note, we are collecting the name and email address of the Lead Coach/Mentor 1 or 2 who fills out the contest entry in order to ensure only ONE contest entry per team is received, to follow up with your team if needed, and to notify you if your entry is selected.
Robot Software / dev laptop holder inside cabinet
« Last post by Louis L on June 24, 2018, 08:59:18 PM »
I made a "holder" for the dev laptops in the tall cabinet. We'll use this Fall (2018).

Up until now, the dev laptops were either stored vertically (where they can fall down) or stacked one atop another. Stacking is not a good idea since each weighs 6 to 7 pounds so the bottom on gets crushed (good thing these have a strong magnesium chassis but the LCD is still a weak point). So I made a box with slats. Each laptop gets its own place to sit vertically without leaning on another laptop or falling over. Each slot is labeled 1, 3, 4, 5, 6, 7. There is no "2" since that laptop has been retired and used for parts. Everyone using a laptop is expected to put it back in the correct slot.

Above this unit, there is space for the chargers so they no longer will clump up on the shelf.
Things we learned and useful other info / Avoid initializing at power-time
« Last post by Louis L on May 21, 2018, 02:29:49 PM »
For 2018 (Panthera in PowerUp), the Pigeon IMU is initialized at power-up. This is when the orientation of the robot is established. Since we're using the IMU to provide field-centric driving compensation, it means the robot must be powered-up on the field, pointed in the correct direction.

At BattleCry, in the 2nd match of the elimination round, the officials requested that robots be powered on in the queue to speed up the connection process when setting up on the field. This meant our robot was no longer pointed in the right direction when the match started and both auto and the controls did not work as expected and the results weren't pretty.

  • Hardware power-up sequences that can affect game play should be done at the start of auto or the start of tele as needed.
  • If the above can't be avoided for performance reasons (for example, if the init sequence takes too long during auto), we need a hot key to do a re-init at game time. Better to waste a few seconds and forego auto than to ruin the entire match.
Program Management / Re: Post-RIDE discussion summary
« Last post by Louis L on May 09, 2018, 11:37:02 AM »
Made what is probably the last update to this thread.

We tested the climber last night and the camera the night before so all hardware mods are done. There is some minimal cleanup to do still - strap some wires down and grease the drivetrain. But aside from that the robot (hw and sw) are done. We have next week to practice before BC19.
General Topics / Re: Driver station - beyond the joystick and game controller
« Last post by Louis L on May 09, 2018, 11:32:16 AM »
I ordered a "kit" that consists of a small USB board with headers and a bunch wiring for connecting to arcade-style buttons and joysticks. Actually I got 2 different ones. They sent me the wrong one the first time; then sent the right one but told me to keep the first one. The first one has half the number of connections as the second one.

I need to poke around and see what this all means in terms of how the various supported buttons and joysticks map to a "real" controller like an xbox unit.
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