Friday, February 24, 2017

Day 48: Recap

So we had a bit of break but we'll try to keep things updated as we move through the competition season.

Week 6
Here is the state of the competition robot that we bagged. We didn't really get to perform a full system check on it but we are confident the subsystems work.

Gear Intake
We are very pleased with the state of the gear intake. We have the control system working on it so their automatic gear pick up routines that lower the gear intake, spin the intake wheels and pickup the intake once the driver drives it into a gear. We were looking into using an IR proximity sensor to determine when we had a gear but it was having some difficulty getting tuned to the right distance so instead we realized we could just determine when the roller starts drawing more current which means the gear is fully back to the roller so the motor become the sensor. We are also adding some protective Lexan to stop the gear intake from damaging itself. We are also adding some additional roller tube to the intake that allows us to intake the gear when it comes in further to the side of the intake.

check_in Week 6
Look at check_in episode 7 for a better description of the past two weeks.

Build doesn't end
The competition robot may be in the bag but build season isn't over. We will continue to iterate on our design for the next 8 weeks until Houston Champs.

- Spectrum

“Engineering is a great profession. There is the satisfaction of watching a figment of the imagination emerge through the aid of science to a plan on paper. Then it moves to realization in stone or metal or energy. Then it brings homes to men or women. Then it elevates the standard of living and adds to the comforts of life. This is the engineer's high privilege.” - Herbert Hoover

Tuesday, February 7, 2017

Day 32: Sheetmetal should be in tomorrow

Look for our big blog post tomorrow night after we get our sheetmetal back.

We have been preparing all our parts to assemble the robots once we get our parts back tomorrow.

We have been printing parts including a nice camera mount.

Also preparing our shooter motors with encoders and making the cabling nice and neat.

- Spectrum

"Blessed are those who can give without remembering and take without forgetting." ~ Elizabeth Bibesco

Sunday, February 5, 2017

Day 30: Superbowl Bot Building

We are still working on getting our parts ready for the sheet metal delivery.

We have our gears and wheel modules ready to be bolted up to the sheet metal when it arrives.

We also have powder coated Versaplanties for the competition robot ready to go as well.

- Spectrum

“The implication of this might surprise you, though: when the tough parts come along, the rejection and the slog and the unfair bad breaks, it makes sense to welcome them. Instead of cursing or fearing the down moments, understand that they mean you've chosen reality, not some unsustainable fantasy. It means that you're doing worthwhile, difficult work, not merely amusing yourself.” - Seth Godin

Saturday, February 4, 2017

Day 29: Adventures in Making a Rack and Pinion

Now that sheet metal has been sent out, it's finally time for us to buckle down and figure out some of the smaller parts on our robot. Among these smaller parts is the plate we plan on using to cut off individual lanes in our three-wide shooter.

CAD model for said plate

Our plan for actuating this plate was to have it driven by a REV Smart Servo mounted in the inside of our shooter tower via a rack and pinion. This seemingly simple task proved to be the cause of numerous attempts to fix open contours in Solidworks before realizing that rack teeth do not, in fact, use the same profile as gears and are simply trapezoids. With the annoying geometry problem out of the way, the question then arose of how to know what dimensions define these trapezoids. The annoyance was further exacerbated by REV's use of the metric module to define their tooth spacing instead of the diametrical pitch more commonly used in the imperial world. 

After a number of google searches (including re-learning what such technical terms as "diametrical pitch" even mean), we eventually discovered a useful whitepaper on the Iowa State University website which outlines how to design gear and rack teeth given certain parameters for your tooth profile. After copying their spreadsheet maths into our Master Sheet, we were able to successfully model our rack. A copy of our spreadsheet can be downloaded here.

Sample spreadsheet outputs for REV Smart Servo pinion

The rack tooth designed from the above spreadsheet data

Closeup of rack and pinion

-Will S, Spectrum

"I must not fear.
Fear is the mind-killer.
Fear is the little-death that brings total obliteration.
I will face my fear.
I will permit it to pass over me and through me.
And when it has gone past I will turn the inner eye to see its path.
Where the fear has gone there will be nothing. Only I will remain." - Frank Herbert

Wednesday, February 1, 2017

Day 26: Preparing for Sheetmetal

With the main sheet metal order sent off to our sponsors we now have to prepare all the rest of our parts.

We began making some new shooter rollers using white silicone instead of black latex.

We also have been organizing all our subsystems and doing inventory to ensure there is nothing we need to buy for either the real robot or the practice robot.

- Spectrum

“It's not the load that breaks you down, it's the way you carry it.” ― Lou Holtz

Day 25: 2017 Spectrum CAD Model

2017 Spectrum CAD Model - "Gamma Ray"

Our main sheet metal order for our robot has been sent over to our wonderful sponsor Solarcraft Inc. So that means are robot CAD is nearly complete. It's still missing a few details but largely the mechanisms are complete and assembled in CAD. We are releasing all of our CAD this year every week and this week we are even uploading a STEP file so you can view our robot model in any CAD package that you choose.

Full CAD Model STEP File

Full Solidworks Models can be found on our website.

Items still missing from this CAD
- Lexan for the entire Fuel Tank on the robot
- Some wheels on the intakes and back elevator
- All the belts and some of the chain runs are not shown in the model
- The bumper noodles and cloth
- Parts of the climber that will help align up to the rope (we are planning to use some type of velcro)

Gear Intake

Our gear intake subsystem showed the most improvement over the weekend. It's a simple solution to a complex problem. The main concept is a thin material slides under the edge of the gear and then a roller brings the gear in to place. We are using a BAG motor with a Versaplanetary to power the roller and another BAG motor and Versaplanetary to raise and lower the entire mechanism. This mechanism folds down between the bumper gap that is open for our Fuel intake.

Mecanum Intake

Our mecanum intake will allow us to gather far more balls then just using the intake between our bumper gap and also lets us gather balls that may be directly against the wall. We are raising and lowering the intake using pneumatics but we also have two gas springs on the mechanism so if we ever lose air pressure during the match our intake will default to the up position. This should allow us to continue scoring gears the more important game pieces even if we have a pneumatics leak.

Final Thoughts

Let us know if you have any questions or suggestions. We are sharing our progress to hopefully inspire more teams but we also would love feedback. If you see something we are doing and think we can improve please let us know.