Day #24 – 1/26/15 – Rainy Monday

Lab opening time: 1:30pm

The goal of today’s work session was to finalized the robot base and the placement of the electronics. The CAD and prototyping teams worked closely together to help finalize some of the ideas that we have been working on for the last few weeks. The first item that needed to be finalized was the actual size of the robot. It was determined that the length already determined was good but that the width of the robot would depend on the width of the elevator and forks.

After some testing and discussion, it was decided that the drive base should be 39 inches wide in order to accommodate both the can and totes being lifted by the forks. We also tested to see that the intake rollers could intake a can to help the can be positioned correctly for the forks to grab.

Much discussion took place regarding whether the can should intake over the forks in a lowered position, or whether the can should intake with the forks in a raised position, and then forks lowered over the trash can, then raised again to lift the can.   Due to intricacies of the “hinged-flap” mechanism used to lift the totes, and differences in size between the two game objects, we determined that the simplest way to proceed forward would be to intake the can onto forks in a lowered position.  We saw no significant benefit to lowering forks down over a can, and we were concerned about the potential of bending the elevator forks in the process.

Another design aspect that was discussed was having intakes on the back of the robot that would be able to take in totes from the human player station back. By intaking the totes from the back, we could take in totes from the human player station and then drive straight to the scoring platform without having to turn around. This idea was later replaced by having a “door” style intake with wheels on top and on the bottom. The top wheel would be for speeding up the intaking from the feeder station, and the bottom would be for normal intaking.

Rough prototype of back intake system.
Rough prototype of back intake system.

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In the process of testing the idea, we needed to know whether or not it would be worth it to invest the time and materials in making a power-assisted intake system. After many tests of loading totes from the human player station, it was determined that we could theoretically build a stack of six totes in 18 seconds from the human player station. After determining the advantages of a back intake system, we started on the design of the mechanism. Our idea was to have doors that would open and close to help guide the totes and to also keep the totes from sliding out the back and then have intake rollers on both the top and bottom of the doors.

We discussed the benefits and downsides to loading totes through the elevator from the rear of the vehicle.  We determined that the benefits did not outweigh the downsides, and decided to stick with a front-loading design.  A rear-loading design would likely be heavier, requiring additional motors and structure, and would significantly alter the design and construction of the elevator.  Furthermore, an additional structure or mechanism would be needed to keep the totes in a repeatable position within the vehicle while rear-loading.  Therefore, the rear-loading idea was logically eliminated from any further progression of the design.

The decision to make a front-only loading robot means that the robot may have to rotate to place the totes on the scoring platform, but we see this action as only a minor inconvenience.

Today the business team, web team, and media team, joined forces and decided to enter the Media and Technology Innovation Award that is offered through FIRST. They are hoping to win by having a good branding style, awesome website, and an up to date website.  The business team also updated the Kickstarter with pictures of Clark’s Expo and Mountain Avenue’s Science Fair.

Programming worked on mounting the swerve module to a piece of plywood with caster wheels to that they could test out their code with only one working swerve module.  We were able to drive it around the floor with some degree of direction and control, but a robot with all four modules will handle much better.  There were some issues with encoder mounting that need to be resolved.

Devon, Alexander, and Daniel working to put together the swerve mount.
Devon, Alexander, and Daniel working to put together the one-wheel-drive swerve robot.

Hopefully by the end of tomorrow, we will have box tube cut, a finalized robot base, and will be ready to start on manufacturing.

Back intake drawing.
Isometric view of the overall robot concept “CrayolaCAD”, drawn in Microsoft Zoomit.  Believe it or not, this software is used for a majority of our design work.

We developed a concept to have both high and low intake wheels.  The lower wheels would be used for taking in totes from the floor, and the higher wheels would be used for accelerating the intake of totes from the human loading station.  Each pair of wheels would be mounted to a pivoting “wing” or “flap” and be driven by a VexPro VersaPlanetary, BaneBots 550 motor, and hex shaft.  A slight spring tension inward would give the wheels grip on the object they’re pulling in, while allowing outward movement to contour the shape of the surface and angle that the vehicle approaches the object.  We believe we can save 1 second per human-loaded tote by using the upper intake wheels to assist the tote in making a quick exit from the loader chute.  These wheels and their associated frames would be located outside the transport configuration, but capable of folding back into the transport configuration.

Intake concept, showing upper and lower intake wheels.
Intake concept side view, showing upper and lower intake wheels.

Lab closing time: 7:45 PM.