While the bulk of my posts are mostly about the what, and what happened so far, the blog and general project goal is not only how to build a robot, but rather the process being used for building a robot. The goal of this project is to see and understand how the engineering design process functions and how the time factor makes an impact, and comparing the final product and process to past years, when we didn't use the engineering design process. Because we currently have some time, but not lots of time, a lot of ideas, and solid machining ability, as this year we prepared everyone to use the now available machinery, we have been going in and out of the conceptual design and preliminary design phases using cheap parts (PVC, wood, etc.) for the different mechanisms, creating many ideas, then building and testing them.
The extra prototyping gives us alternate options before it gets too late in the season to change, in the case of something we thought would work turns out to not meet expectations and requirements. While it does add extra work, this method of having "competing ideas" allows us to choose the prototypes and concepts that best reach and exceed the requirements and standards we made for ourselves and move on from there. This, of course, gives a better chance for a more improved final product.
In comparison to the past years, we are much more prepared, as we have now eliminated any financial restrictions through heavily fundraising throughout the offseason, created a partnership with a growing organization that gives us access to a full machine shop for our purposes (3D printers, laser cutters, lathes, drill presses, table saws, etcetera), trained every member how to use any machinery, and showed examples of different mechanisms and structurally sound parts. This means, the only major factor is the clock, as the other factors that may effect the build season are mostly taken care of.
In the past years, we only made at most one prototype scorer. While we were somewhat lucky both worked, part of the luck was due to other teams posting their mechanisms, all giving us the concepts well into Week 2 and early Week 3, and spent most of Weeks 1 and 2 discussing strategy and learning how to use power tools. With the ability now to quickly machine basic and cheap parts, we can be one of the teams that releases successful prototypes within the first couple weeks, as we have so far done.
As a summary of the conclusion to Week 1, the engineering design process has been much better than past years, and time has not been much of a factor.
Thursday, February 6, 2014
Wednesday, February 5, 2014
1/11/2014 Day 7: A Smaller Team
Today was primarily a day for programmers. As today was the VEX Robotics Regional Competition in Sahuarita, a solid chunk of the team was missing (6 members and 1 mentor), and another two gone for the weekend. This left one of the mentors to work with the mass of programmers (almost everyone at today's meeting), and the other to work with the couple mechanical kids left. As the elastic puncher was not yet eliminated from the jaws idea, that is what was worked on today, just using a PVC pipe, a 2' long piece of 2"x4", and lots of elastic tubing. The puncher worked very similarly to a bow and arrow, but with the arrow being larger and attached to the bow. This means when the bow/surgical tubing was pulled back, the puncher was "loaded" and ready to shoot, and the surgical tubing would be let go, thrusting the PVC pipe forward, punching the ball.
By the end of the day, the puncher was finished and tested, but was considerably weaker than the catapults.
By the end of the day, the puncher was finished and tested, but was considerably weaker than the catapults.
1/10/2014 Day 6: Continued Integration Discussion
Today was similar to yesterday, but we began to optimize different methods for our intake and shooter mechanism/created a spreadsheet of important qualities of an intake and a shooter. With this, we made a conceptual rank/effectiveness score for each differently styled mechanism for each quality. The main question was whether or not to go with it all in one assembly/unit. If it were one assembly, the passing would be precise and easy, but the shooting would be less powerful and inconsistent, as it would be the normal aiming, but with a puncher, not a catapult, which, again, we figured wouldn't be as effective. With an intake roller separate from the catapult, it would be slightly less controlled (passing), but shooting would be great, whether a pneumatic catapult or elastic catapult is used.
The single unit would be called jaws, since it looks like they could be jaws, in that there are two crossing structures, the one crossing to the top with rollers, the other static and used as a track for the ball, and a puncher by where they intersect, so the shooter pivots with the intake. On the other hand, there is the assembly where the shooter and intake mechanisms are independent of each other.
Approximate times of working: 3:30 PM -7:30 PM
The single unit would be called jaws, since it looks like they could be jaws, in that there are two crossing structures, the one crossing to the top with rollers, the other static and used as a track for the ball, and a puncher by where they intersect, so the shooter pivots with the intake. On the other hand, there is the assembly where the shooter and intake mechanisms are independent of each other.
Approximate times of working: 3:30 PM -7:30 PM
1/9/2014 Day 5: Integration
Today was a bit of a slow down day, just to ensure everyone is on the same pages and the different mechanisms are still compatible with each other. Instead of continuing the preliminary design phase for each of the individual mechanisms, we went back to the conceptual design phase for the robot and it as a whole, something we hadn't done yet. After spending the day in small groups and conceptualizing, the general wants were all the same, a roller intake, a shooter/catapult, and a fold-out catcher. This meeting, again, was primarily for getting the group on the same page, and was beginning to mark the end of the conceptual design process.
Approximate times of working: 4:00 PM -7:30 PM
1/8/2014 Day 4: Success!!!
Shooter
Today we built our first prototype catapult (that actually worked!!!), which can be seen in this video. After figuring out the shape of the "flinger" was the problem, we changed from the bent chair legs to just a piece of conduit bent twice. Both "flingers" can be seen in the video, the conduit mounted on the cart being used and the chair legs sitting on the bottom of the cart. The biggest problem was the general geometry. The flinger has a constant angular acceleration, but that translates to linear acceleration based on how far away the ball is from the pivot point. Because the chair legs are bent at half the length, the end of the chair legs prevent the ball from getting to the back of the chair legs, which would be the same as using a straight "flinger" that is half the length, meaning half the linear acceleration. This is the main reason why the conduit works so well, since the ball can get to the back of the conduit, meaning larger linear acceleration for the ball since it is further away from the pivot point.
Today we built our first prototype catapult (that actually worked!!!), which can be seen in this video. After figuring out the shape of the "flinger" was the problem, we changed from the bent chair legs to just a piece of conduit bent twice. Both "flingers" can be seen in the video, the conduit mounted on the cart being used and the chair legs sitting on the bottom of the cart. The biggest problem was the general geometry. The flinger has a constant angular acceleration, but that translates to linear acceleration based on how far away the ball is from the pivot point. Because the chair legs are bent at half the length, the end of the chair legs prevent the ball from getting to the back of the chair legs, which would be the same as using a straight "flinger" that is half the length, meaning half the linear acceleration. This is the main reason why the conduit works so well, since the ball can get to the back of the conduit, meaning larger linear acceleration for the ball since it is further away from the pivot point.
This was found after an increase in tension with the chair legs had no significant affect on the ball's flight. This change made the ball go from being shot 3' high and 5' far to 7' high and 25' far, with the same amount of tension. This was now a proven design, although we did want to see whether or not an air powered launcher/puncher would work better or be more compact.
It is safe to say this design of the shooter has now moved out of the conceptual design and is in the middle of preliminary design. We have now shown the concept works and works well, and are in prototyping phases and have made basic CAD models and other drawings.
Intake
Today the intake group looked at ways to build an intake, and have now decided to use information we found from the Robot in 3 Days groups, and past intakes we have built. As expected, roller intakes appeared to work, so the intake team began building a roller intake as a prototype, powered by a drill motor. This was much more desirable than a claw due to the speed of the intake and outake.
Drivetrain
Today we began to get the drivetrain working, but it was primarily modifying software, rather than making hardware changes.
Catcher
Today I created a CAD model for a potential catcher, as we came up with an idea to use a funnel. Since robots have to start within their own frame perimeter, but can expand outward after the start of the match. The catcher is similar to a cardboard box with 40" flaps that extend 20" outward.
We had two ideas for actuation (moving the stuff), either directly controlling the sides using pistons, or make the edges like levers, and actuate the levers with either pistons or motors. After discussing both, we made prototypes of each, the first actually using a cardboard box, and the second using PVC pipe.
Now, most individual mechanisms were out of the conceptual design phase, and into the preliminary design phase.
Approximate times of working: 3:30 PM -7:30 PM
Monday, February 3, 2014
1/7/2014 Day 3: First Day Off
This year, my weekends will be on Tuesdays and Tuesdays only (will most likely do work on those days also anyways). As it is Day 3, all (5) of the "Robot in 3 Days" teams released their release videos of their robots. The main robot I looked into was Team O-RYON and their robot "Draconis". As expected, they used a roller intake to pick up the balls, which was effective. Unlike our thought's though, they decided to use some sort of kicker or puncher, which fired, but not overpoweringly. This helped show us a catapult is definitely the way to go. Also, the robot didn't have a catching device, so it required a very accurate throw from either another robot or a human player.
1/6/2014 Day 2: On to the Next Steps, Time to Apply Strategy
Today (first day after school) was the beginning of the splitting into subgroups, which are shooter/launcher, intake, drivetrain, and catcher. Each are definitely at different stages, but all still going according to the Engineering Design Process.
Shooter
After much discussion involving the shooter and playing with the ball, a couple concepts were thought of. As there was a similar game in 2008, we mostly pulled from the knowledge and past experience of the mentors, who were on a team in 2008, as well as videos from robots in 2008. As seen by punching the ball in the air, the ball could be launched with a puncher, but only for a fairly short range. Instead of a puncher though, the shooter group began prototyping a spring powered shooter using our old robot cart, surgical tubing, a small pole, hose clamps, and some 2"x4".
By the end of the day, we finished and launched twice, but both were ineffective and fairly weak, although this was most likely due to the lack of tension in the surgical tubing. Overall, today was a very promising Day 2 for the shooter. Day 4 will consist of adjustments to the shooter, and the shooter is now already out of conceptual design and burying itself into preliminary design.
Intake
Similar to the shooter, the intake was quickly leaving the conceptual design state, but was stuck in a debating state. As we have worked with different types of intakes, the intake group had several concepts down, and it is more so a matter of the catapult group to finish first. Similar to the other past designs, the two primary ideas are a roller intake and a claw intake. The roller intake would need at least one motor to power it, while the claw would need at least two motors or three pistons to power it.
As roller intakes are simpler and almost immediate in the intake process, while a claw is a little slower, the idea of using a roller intake is being leaned toward by the intake team. Other options are being considered as a "just in case" a different type of intake might have other advantages. Also, we observed all of the "Robot in 3 Days" teams are using roller intakes for their bots, and are extremely effective and consistent in picking up the ball. The biggest question, though, as brought up previously, is "What is most compatible with the shooter?"
Drivetrain
As we decided to use a basic tank drive, we plan on using a modified kit bot, 6 wheels and 6 CIM motors (simplest thing that meets and exceeds our requirements). The size of the kit bot is 32"x32", which is too large, but the launcher is needed before modifying the drivetrain. Although it will be modified, the drivetrain team finished putting together the large kit bot and started mounting the electronics to it, so we can test any prototypes we build.
Catching
While the other three are essential and absolutely required for the robot, the catching mechanism is what I decided to work on, due to a previous lack of concepts, other than increase surface size, and lack of interest on the catching mechanism from other members. Today the catching team worked on possible ideas of catching shapes, with a funnel as the easiest, since it is passive and the most logical shape for catching and passively directing an object. By the end of the day, we had a general idea of how it would work and be actuated, but was not yet sure what material it would be made of.
Approximate times of working: 3:30 PM -7:30 PM (Half hour break in between)
Shooter
After much discussion involving the shooter and playing with the ball, a couple concepts were thought of. As there was a similar game in 2008, we mostly pulled from the knowledge and past experience of the mentors, who were on a team in 2008, as well as videos from robots in 2008. As seen by punching the ball in the air, the ball could be launched with a puncher, but only for a fairly short range. Instead of a puncher though, the shooter group began prototyping a spring powered shooter using our old robot cart, surgical tubing, a small pole, hose clamps, and some 2"x4".
By the end of the day, we finished and launched twice, but both were ineffective and fairly weak, although this was most likely due to the lack of tension in the surgical tubing. Overall, today was a very promising Day 2 for the shooter. Day 4 will consist of adjustments to the shooter, and the shooter is now already out of conceptual design and burying itself into preliminary design.
Intake
Similar to the shooter, the intake was quickly leaving the conceptual design state, but was stuck in a debating state. As we have worked with different types of intakes, the intake group had several concepts down, and it is more so a matter of the catapult group to finish first. Similar to the other past designs, the two primary ideas are a roller intake and a claw intake. The roller intake would need at least one motor to power it, while the claw would need at least two motors or three pistons to power it.
As roller intakes are simpler and almost immediate in the intake process, while a claw is a little slower, the idea of using a roller intake is being leaned toward by the intake team. Other options are being considered as a "just in case" a different type of intake might have other advantages. Also, we observed all of the "Robot in 3 Days" teams are using roller intakes for their bots, and are extremely effective and consistent in picking up the ball. The biggest question, though, as brought up previously, is "What is most compatible with the shooter?"
Drivetrain
As we decided to use a basic tank drive, we plan on using a modified kit bot, 6 wheels and 6 CIM motors (simplest thing that meets and exceeds our requirements). The size of the kit bot is 32"x32", which is too large, but the launcher is needed before modifying the drivetrain. Although it will be modified, the drivetrain team finished putting together the large kit bot and started mounting the electronics to it, so we can test any prototypes we build.
Catching
While the other three are essential and absolutely required for the robot, the catching mechanism is what I decided to work on, due to a previous lack of concepts, other than increase surface size, and lack of interest on the catching mechanism from other members. Today the catching team worked on possible ideas of catching shapes, with a funnel as the easiest, since it is passive and the most logical shape for catching and passively directing an object. By the end of the day, we had a general idea of how it would work and be actuated, but was not yet sure what material it would be made of.
Approximate times of working: 3:30 PM -7:30 PM (Half hour break in between)
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