June 27 meeting: Accumulator Prototypes

The teams were VERY productive at our June 27 meeting.  Off the bat we continued driver practice and training with 20 minutes of object avoidance.  The team members are beginning to get comfortable controlling their robots and, even at this early stage, you can start to see how the commitment to driver training is going to pay off.

 

After that the bulk of the meeting was spent on building 3 accumulator prototypes for testing.  The crew got ALL of the work done in our time frame and we learned a ton.  1414A prototyped a polycarbonate ramp (we knew we wanted polycarbonate sliding under the sacks based on early meeting testing) with an "FRC-style" roller made from high strength gears, threaded beam, and covered in no-slip pad. 1414B prototyped a polycarbonate ramp with tank tread rollers doing the collecting. After initial testing this crew also added VEX foam to see if coefficient of friction could be improved.  1414C prototyped a polycarbonate ramp with just tank tread sprockets doing the active collecting.  Here's a quick video showing some of our testing:

From prototype testing here's what we learned:

1. Simple use of tank tread sprockets does not provide enough friction to gather sacks.
2. We liked what the tank tread rollers could do after covered in foam, but the weren't as efficient as we would like and this will be a heavier system to lift.  The speed at which this diameter spun was highly desirable though.
3. The FRC-Stlye Roller/non-slip pad looks to be our best option for sure! We're going to proceed with this design, but look for ways to speed up the intake using a favorable gear ratio.

4. All of our prototypes were single-motor powered and did not overheat during testing.  Good news, because we'll be using two motors on the real system and it seems as though we won't have to overwork the system.

5. The "mouth" opening between the roller and polycarbonate with have to be of a flexible distance in order to accommodate sacks in multiple orientations with shapes changing while accumulating as well as dealing with sacks on top of each other.

6. Since the polycarbonate slides so easily under sacks we will want the polycarbonate to contact the sacks BEFORE the roller contacts the sacks to help ensure smooth accumulation.

Looking forward to our next meeting when we figure out arm/lift/linkage geometry and ratios!

-Kressly

June 20 & 22 meetings: drivetrains & inspiration

At our June 20 & 22 meetings the last parts of functional drivetrain work were completed and some lengthy testing and driver training commenced.  Driver training thus far is comprised of "follow the leader" exercises with robots oriented in varied ways in relationship to each driver and some "obstacle avoidance" training has also begun to avoid sacks we cannot push and/or do not want to pick up.  While these types of activities seem somewhat insignificant, these are the initial steps in a steady regimen of driver and operator practice designed to have each of our drive teams know how to pilot their robots instinctively and as flawlessly as possible in the heat of competition.  Thus, this early and persistent focus on the interaction and relationship between robot and human is every bit as important as a hitter in baseball getting in tee and batting cage work or an artist practicing his/her craft until perfected.

Here is  a string of three videos that demonstrate some of our follow the leader activities:

With some extra time we had at these two meetings we discussed three accumulator designs we will start prototyping at our next meetings and the probability of using a 4-bar linkage to life sacks into scoring position. 

Lastly, for inspiration, we also viewed the documentary Atlantic Crossing: A Robot's Daring Mission
One of my former students is a part of this incredible team that is revolutionizing ocean exploration:
http://wh.rutgers.edu/collaborations/atlantic-crossing

Looking forward to see how things progress!
-Kressly

June 7 Meeting: Focus on the drivetrains

No frills at this evening's meeting it was 90 minutes all about getting as close to drivetrain functionality for all three teams as possible.  1414A has a fully completed and functional drivetrain, 1414B & C both had a little more work to do as their new electronics needed paring and firmware upgrades along with mechanical assembly work.  Both of these teams completed paring the electronics and 1414B also completed the firmware upgrade.  B will be up and running after completing motor wiring while 1414C just needs to wire and upgrade firmware and software.  Tonight, all the teams helped each other, learned about labeling motors by port numbers, and shared responsibility for getting work done.

In the end, all teams celebrated a solid effort taking turns test driving the complete 1414A drivtrain:

http://www.youtube.com/watch?v=3z90kJpvzhU

Photos from the meeting can be found here:
http://www.flickr.com/photos/uprobotics/sets/72157630077752494/

See you all in two weeks, when we switch over to daytime/twice a week meetings.

May 31 meeting: Drivetrain build begins

After a few weeks off to digest our findings from Stubots, contemplate our brainstorm, and prepaint aluminum for our three teams (see pic here: http://farm8.staticflickr.com/7245/7315321084_0aa7ba754d.jpg blue=1414A, gold=1414B, white=1414C), we got back at it last evening to focus on our desired drivetrain characteristics and begin the build.

Essentially our findings concluded our teams would design a nearly identical drivetrain to Kwelaha from last year.  We feel that a Sack Attack robot with these drive characteristics can be very effective.  Zero turning radius, omni-directional capabilities, and familiarity for returning drivers and pit crew members all help us arrive at an easily-controlled, agile, maneuverable robot.  We did have discussions about a shorter drivtrain to allow for a robot-wide accumulator later, but concerns over tipping with an arm elevated led us to build a full front 8-wheel H drive.  We can always remove material and wheel later if we choose, but if we cut expensive aluminum now, it would cost us dearly to add back on later. 

We also determined our Sack Attack robot drivetrains would have slightly different characteristics:
1. the chassis has to be as close to the floor as possible - not allowing sack under/in the wheels
2. we need more space in front of the front wheels to be able to add "angular encouragement" of sacks to the accumulator (should we keep the full front).
3. With three teams and the budget tight, we need to conserve parts even more so than we did last year.

With all of that in mind our teams worked hard, helping each other as needed and got three drivetrains more than 80% done.  The tachquiwi concept is alive and well with this group!

We concluded the meeting with our engineering notebook entries - so far we're doing a MUCH better job at this than last year!  Special thanks to our visitor Alex Arocho, a Temple Univ. engineering student who may be helping us out from time to time. Thanks, Alex!

We also uploaded all of our May meeting photos to our gallery, here: http://www.flickr.com/photos/uprobotics/sets/72157629999817456/ Enjoy.

We hope to have all three drivetrains running next week, so check back.