Well there has been a lot of interest lately with crab/synchro/swerve drives as of late which has inspired me to create one of my own.
This robot is able to drive in any direction while facing in any direction by both rotating and driving all four wheels.
For my version I decided to place the driving motors on the wheel modules. The disadvantage of this is that the wheel modules become very large making the overall robot large. But overall the advantages outweigh the disadvantage of size. Having the motors on the wheel modules greatly simplifies the gearing needed the power the wheels. With less gears needed the amount of backlash that is common in most LEGO inventions is negligible. Also by having the motors on the wheel modules leaves more room for the steering mechanism.
This picture shows a close up of two of the wheel modules:
There are two types of wheel modules used on the robot. There are two powered and two non-powered wheels modules.
Steering is acomplished by two motors located centrally on the robot. These two motors are geared together to power the steering for both the front and back wheel modules.
The following two pictures show the steering mechanism:
(Pictures were taken before the wheels were properly synchronized)
A video of this robot in action will be posted as soon as possible.
Please feel free to post any questions and comments.
Since lego league is over for my team I am exploring options for next year… I think you used four motors didn’t you?
-Greg The Great
I would strongly advise not to do anything like this in Lego League for multiple reasons
First there is the amount of motors used just to drive. Mine uses four, two for drive and two for steering. You will need a minimum of three motors to make an effective driving base leaving you with no powered special function (arm/claw).
Second would have to be the size of the robot. I got a chance to play with this robot a little bit on this year’s playing field and found that it was just small enough to fit threw most of the passage ways. Any slight variation of course would have caused it to either jam between something or destroy playing field pieces.
Next would be that you would need a minimum of two rotation sensor for any kind of accurate control. One for controlling steering and another for measuring distance.
The fourth reason would be alignment issues. Each wheel module is able to get slightly out of alignment from the others due to gear backlash. This is fine if you are driving it around with remote but makes autonomous control extremely hard because of its unpredictable curving when trying to drive straight.
All of these disadvantages add up and I think would really cause a lot of stressful meeting for the kids.
is it just me or is it so annyoing that there is only one variable setting on lego motors…like if you turn them down you turn down both speed and tork? its so annoying!!
This can be fixed… through careful programming and sensors positioned correctly… Sensors often provide good results when used correctly… The line sensors are a pain in the put (especally with this years game) but rotation sensors work miracles. They can be used in ways that only a little kid could think of…
Keep in mind… It will only count as fast as the RCX can process it… If it means loss of torque… then do it… This years game only needed torque for the ATV test… so don’t use the counters on it…
Lego League is not a question of torque it is a question of programming… the better the programming the better the robot… You might have the best robot in the world but without using good programming you will run out there and get a 50 point match… where as if you have a “bad” robot with some awesom programming you will be liable to get a 200-300 point round average (talking from experence)
Well Thats My Nickel…
-Greg The Great