FIRST Team 1277 Web Log

As we experience every robotics season about this time, doubt rises questioning what if anything will be working come the bag and tag date which is now only 2 weeks away.  We’ve had a very snowy week again, missing an additional 2 days of school. This resulted in 2 fewer robotics meetings further impeding our progress during this build season.  We’ve decided to start meeting on Friday’s to help resume the pace.  Even with these challenges, we have reached several milestones worth discussing.

A news article was written by one of the club’s students about the kickoff event and our club.  This article will soon be published in the Groton Herald along with a more recent picture of our club’s members.

The tee shirt design is just about completed.  The team is anxiously awaiting the unveiling of this year’s tees.  We are hoping to order them soon giving the graphics company enough time for a pre-competition day delivery.

We have now officially conquered the problems with the mecanum drive.  Software updates in the WPILIB still have not been released so we fixed the problem by overriding the RobotDrive class in our own software.  After some additional testing and proper motor inversion on the right side motors, the robot rides, glides and slides omni-directionally.  It was a real morale booster for the team to see this in action.  Several students enjoyed motoring it around.  The wheels do leave a trace of where they’ve been, especially when sliding.  We have ordering new wheels for the competition due to a concern for the loss of traction imposed by this wear.   The new wheels are a bit different in material and shouln’t leave a trace.  Until then, we may need an iRobot Scooba to stay in good graces with the school’s maintenance crew.

The jaguars were changed from “hard stop” to “coast” mode.  Those jumpers are really small, easy to lose and even harder to find.  Nimble fingers and young eyes prevail though.  This change really smoothed out the mecanum drive and will have less wear and tear on the gear boxes.  However, it poses some additional problems for motor control during the autonomous period since it is now more difficult to stop at a specific point.  The autonomous team will need to back off the hammer prior to stopping rather than attempting to jam on the breaks when a stop mark is reached.  There are several ways to implement such gain control which will be worked out by the software team over next few meetings.

Work continues on the robot’s arm mechanism.  The support tower anchoring the robot arm has been attached to the robot’s frame.  A prototype of the arm itself is in the stages of being built which drove home the “measure twice, cut once” philosophy.  The arm will require 2 window motors.  The relays for these have been attached to the robot and tested from botht he hardware and software side of things.  A faulty relay made this take a bit longer than expected.  A result of brainstorming is that there are several similar yet unique ideas on which route to take with the robot arm.  Hopefully these will converge to culminate in the best overall implementation or at least improve our debating skills.

The mechanism for deployment of the mini-bot is still in the design process.  The direction to take and its implementation should be completed in the next few meetings.  The deployment imposes more complications than is immediately apparent.  However, without a doubt, our min-bot team will figure it out.  The mini-bot it self has been assembled and was found to be just over its restricted volume.  It’ll be back to the grinding wheel for this little guy.

The autonomous team was busy at work testing the already implemented robot mechanisms.  The sensors were tested, first with the robot on blocks and then on the carpet (with the emergency stop button in hand).  We are currently only using 2 of the 3 sensors provided in the kit of parts to follow the guide line to the hanger posts.  With very little tweaking, the robot followed the guide line and stopped at the end marker.  Tests were performed with the robot pointing in several different directions to ensure proper direction correction.  The next problem to solve is dealing with the “Y” and accepting feedback to determine which route to take when reaching the fork in the road.  Here it may not be best to take the one less traveled.

All 4 encoders are now mounted and working properly.  Some testing was performed to relate distance to pulses with inconclusive results.  Although there is more work to be done in this area, the encoders will be very helpful in gain control and “Y” location identification during the autonomous period.

There is yet more snow predicted for Saturday.  The school’s maintenance crew requested our team build them a robotic snow blower.  Maybe after the arm is working…

Yes, the drive train is set up.  Lots of mecanum wheel flipping and swapping but we finally got the “X” setup correct.  The electronics were temporarily mounted being sure to mount the battery in the center balancing the weight for the best mecanum drive.

The mecanum drive methods from wpilib were fixed manually in our local copy by the software team.  It was reported on the chiefdelphi forum that a calculation needed to use the result of a sin() rather than a cos() in one location to have the directional movement work properly.

First test was on blocks with the welders at the helm.  Joysticks were reversed and drive wasn’t correct.  The motors were re-tested with tank drive showing the motors needed inversion.    Drive is now better but we still weren’t getting the mecanum drive motion expected.   However the spin mechanism is working well, the side to side slide and directional movement isn’t.  We see a lot of slipping even though we realize that only 70% movement is achieved using this setup.   It seems the motors are not responding as expected.

Prototypes on the mini bot deployment mechanism continue.

The test poll and stand for the mini bot were completed.

Continuing discussions on mini bot deployment and arm.

We are still having problems with the mecanum drive not sliding.

Week 2 became a short week due to the Martin Luther King holiday and yes, another snow day.  However, there was a great deal accomplished.

The problem we were having with the USB image was that it was not properly formatted as a boot disk.  The solution suggested on the FRC forum did the trick.  The classmate was reimaged and all software on the classmate and the team laptop were updated.    The CRIO on last year’s robot was reimaged as well.  The classmate antivirus found a “killbill.exe” virus file on the newly imaged classmate.  It has been quarantined.  Looking at the FRC site, other teams have noticed this as well.

For autonomous mode,   the sensors were connected to last year’s robot, calibrated and programmed.   Duct tape was put on a strip of carpet to simulate the lines on the competition field.   Getting the proper angle for the “Y” proved to be a pain but it is all marked out now.

The materials for the mini bot pole and the tube hangers was purchased.  The hope is to build these next week so they can be used in testing the robot as it comes together.

Since we are using the Mecanum wheels this year we will need 4 gear boxes and 4 motors.  A torque test was performed to determine which gear box to use.  It was decided to use the same gear box as last year along with the CIM motors.  A team removed the 2 gear boxes from last year’s robot, rebuilt them and put together the new ones that came with the kit.  They were attached to a simple frame to prepare for a test drive.  Additional mounting brackets for the encoders are needed to work with these gear boxes.

One of the mentors brought in 4 mecanum wheels from a previous year’s competition.  This will save us from having to purchase new wheels.  New hubs and spacers were attached and the wheels were mounted on the simple frame.

A team got together to assemble the basic electronics and jags.  Once all was connected, the CRIO was imaged, some software loaded and motors were tested.  It seems to be together just fine.  This will be helpful to test a mock up of the final robot as the various robot capabilities come online.

The mini bot parts came in.  The mini bot team was able to put a prototype together.  Initial attempts at climbing the pole found the mini bot shuttering on the pole.  After some fine tuning it looks like the approach will “take off” as was shown during additional test runs with the adjusted prototype resulting in a motor fatality.  Additional motors and fuses were ordered.  Looks like an off switch should be the next thing prototyped.

Some students reviewed the Website design looking for possible way to improve the team’s experience with it.  This web log is one of the results of that investigation.  Additional investigation on accessibility for handicap access and mobile access was performed and information gathered.  The implementation of these ideas is still ongoing.

We officially signed up for the Unveiling Event at the Nashua High School.