In the recent weeks i have been working on a linefollower robot for a competition in my country and now i am considering changing the design of my robot from a 2 wheel + ball caster to a 4 wheel + ball caster. Here are the reasons:
I am in the end of my highschool, and beggining university I want to participate in a line follower robot competition. The robots are about 15cm x 15cm and so is mine. Currently it can go around 0.9 ~ 1m/s in a track of white line and 10cm radius turns, but due to lack of friction between wheels and floor and great distance between center of mass and motors, it is slipping too much and I believe it is the maximum speed for my project, so I am starting a new one of a 4 wheel robot which, in my opinion, would reduce significantly the slipping problem.
Anyone has previous experience with this kind of line-follower? Maybe it can be a resource for future students who are also in this kind of competition (I have not found information about this topic in the internet).
I suspect that a 2-wheeler will be much more nimble, but perhaps you need to redesign the mass distribution. Maybe you need to change your tyre supplier
Thank you for replying manor_royal. Im planning to buy better wheels https://jsumo.com/shop/slt20-aluminum-silicon-wheel-set-33mmx20mm-pair/ that are also a little bit heavier than the current ones, but I believe that i wont be able to keep adding weight to correct the center of mass(due to motor torque), that is why i believe I should go for 4 motors. Also, the top 3 robots in the last year competition used 4 motors. But also, i am using two tb6612, a two motors 1A H-Bridge / 2A continous one motor H-Bridge and i think that it would not be a good choice to put two 1,6A stall motors in each tb6612...
Well, after a search about moment of inertia it seems that the best option is to have the center of mass of the robot right in the line of the wheels (in case of 2 wheels) for the robot to make faster turns. However, as the base of the robot is currently a triangle, the robot would eventually fall behind, and adding a ball caster behind seems not the best solution as far as it would reduce the normal force in the wheels therefore reducing the friction of the wheels.
Currently, using a 4 wheeled robot seems a good solution as far as it would be relatively easily to put the center of mass between all the 4 wheels, making it easy to make turns, BUT in a turn a 2 wheeled robot can relly in the static friction coeficcient, and as far as I imagine, a 4 wheeled robot would relly in the dynamic friction coefficient, making it easier to slip...
