this is the basis for my new robot design. I've place the wheels further forward to solve a balancing issue, but this will limit the ability for the IRseekerV2 to find the ball behind the robot. i'm not worried about this in the slightest, as it actually solves a twitching issue due to the seeker values of 1 and 9 (behind the sensor). this robot uses a single omni wheel placed at a 90degree angle to the wheels as a stabilizing, which should solve any jumping/bouncing issues that occurred due to using a slider.

this robot will be constructed on 3mm plywood, and unlike the previous models, the lego will be constructed to be inline with it self, causing no warping of the robot, increasing it's rigidity. the NXT will be place forward, over the driving wheels to increase the traction of the front wheels. i'll also be using a RCX motor to create a back spinner for ball control.

blue tooth troubles

I believe that my new design will prove most effective. Though it does not utilize Omni-directional wheels and the cosine function to move, it does take the speed and traction of 2 normal wheels, stabilised with an Omni wheel. This, combined with a back spinner means that robot can take control of the ball.

The logic for the blue tooth communication is simple- I will program the robots to find the neutral zone lines on the field and drive along them. If the robot detects that it’s motors are ramping up (and thus, the ball is being challenged by a second robot), it will call it’s team mate to move up the other neutral zone line, where the first robot will act to pass the ball across the goal.

In practice however, the programming is not that simple. While this idea takes comes to fruition through the creation of near identical robots, putting it into practice is slightly more difficult. First I need to come up with a way of getting the compass sensor working. This is a difficult tasked with a 2 wheel design, as it means fancy manoeuvring around the ball, which can be very time consuming. What I’m thinking is instead of that, have a tag team approach. Have one robot in the goal at all times, and when a robot is facing the wrong direction, it alerts the defending robot to the position of the ball, then retreats to take over.

This can only come through proper testing, so we’ll see how well it goes.

the ball

have been doing more research on the new ball.
the rules do not allow the ball that is actually in use to be used:

2.2. Ball Suppliers.
2.2.1. The official balls for all RCJA tournaments will be:
IR Roboball MK2 made by Wiltronics http://www.wiltronics.com.au/catalogue/shop.php?cid=339
EK RoboSoccer RCJ-05 ball available from Modern Teaching Aids (http://www.teaching.com.au/lego_robocup.asp )

the ball in use is the RCJ-05 ball made by EK in japan ( http://www.elekit.co.jp/material/english_product_html/RCJ-05.php?page=2&ssi=2,3,19 )
this ball uses a step wave at 40 Hz. it's peak wavelength is 940nm.

this means to find it with a regular light sensor you would need to poll the sensor twice with a 0.040sec delay between the polling code as follows:

IF port_1 > 35:
run ball_found_module
ELSE:
WAIT 0.040 sec
IF port_1 >35:
run ball_found_program
ENDIF
ENDIF

Thoughts after state

having finished Second in state with a robot that was built 3 days before and code that was no where near finished i think i need to address some of the short comings:

firstly the failure of the compass sensor. had i been able to effectively use the compass sensor in my program, i could have stop a number of own goals being scored. unfortunately, it never worked. i need to work on a way of prototyping the algorithm i want to use, which means running it by people who understand maths much better than i do and working out exactly how to run calculation with a maximum value of 360.

the second major problem was the horrendous lag created in the program, with the robot jerking and stuttering, and generally not running very smoothly. i have a feeling that this actually cost me the grand final more than anything else... a smooth running robot is more effective than one that stutters uncontrollably and has trouble finding the ball.

the third major issue i had was detecting the range of a pulsing ball. while the IR Seeker V2 would always find the ball it could not tell you distances enough. this meant that there where major issues of the ball being in directly in front of the robot and it not being able to find the ball, instead the robot doing a little dance. it would get "stuck out of phase" polling the ball outside the 40Hz pulse and missing it.

if i can address these major issues, then we'd have a strong entrance into the nationals. on the other hand, if i can find a way of addressing all these issues and adding both communication protocols and positioning values into the program... i think we could win not only standard but premier with the same robots...

to do list

the purpose of this Blog is to document progress and ideas. first thing i want to log is a too do list.

1. redesign the robots... standardized the design (will help when working on communication). this includes deciding on a drive train and developing an effective back spinner or kicker.
2. attempt to learn robot C (but possibly not as i want to get the communication working between the robots...). if not, find the most effective language which allows for effective blue tooth communication.
   
3. work on getting a compass sensor working to stop scoring own goals and make shooting goals easier
4. get the downwards pointing light sensor working- will allow the robot to follow lines laid out on the mat and angle for goals, etc
5. design a set of heuristic rules for communication between the robots
6. design an effective set of communication procedures (optimistically getting the robots to pass the ball around goal keepers, getting the currently attacking robot out of the way, etc)
   
7. complete a set of live tests (against ourselves and other schools)

other things to do include:

• learning the current rules
• fighting school to let us go to nationals
• convincing school to buy new sensors.
• working with other schools for friendly matches
• finding transport to national competition.
  
• not letting it effect my HSC too much (yeah right.)