pic: Team 1619 Presents: Compositron

[mott]

Originally Posted by Canon reeves

Great robot! I do have a few questions however. So why did yall go with tank treads? what are the advantages/ disadvantages? Is the turning really good? how fast does it run?

It's my first year working with the tank treads so some of the other 1619 crew might be able to add their thoughts but here is what I'd say:

Advantages

1 Simplicity of the system - We don't need a system of drive belts/chains to get 8 driven wheels...the treads actually dual-purpose as the drive belt and the tread material. Since we run the center 2 wheels on each side dropped, we can establish our overall belt length and then freely adjust our dropped wheel positions by simply relocating our drop wheels. For us this is further simplified by our 1x2 extrusion frame rail into which our drop wheel axles are attached...giving us almost unlimited options on our drop wheel base.

2 Cost - While this system would otherwise be somewhat costly, we are fortunate enough to have a great partnership with BRECOflex so cost actually becomes an advantage of this system for us. BRECOflex has been a great supporter of our program for a number of years.

Disadvantages

1 Cost - As mentioned above...for the general population, this system would be more costly than other available options.

2 Single Point of Failure - Unlike wheeled 6/8 wheel skid steer systems, a tread system must be direct driven on one of the end pulleys. This means that if a tread belt fails, you are essentially totally crippled on that side. With a wheeled system, you'd likely direct drive one of your dropped wheels, making a drive belt/chain failure less catastrophic. While tread belt failures have been rare in our teams history, they do happen (QF 1.1 in Utah this year) and it is almost impossible to predict when they might occur.



Turning Question - With our drop center design, turning is no issue for us. Without looking closely at our machine on the game field, you'd probably never notice that we were running tank treads simply by the turning dynamics.

Speed Question- Our gear ratio was selected based on acceleration and total required time to cover about 20ft. We assumed that most game actions in Aerial Assist would take place in this distance so we run Ball Shifters with a high gear (7.1:1) floor speed of about 12fps. The tank treads are essentially irrelevant when it comes to speed as we could have chosen any desired gearing and run as fast or as slow as we wanted.

Let me know if you have any other questions and thanks for checking us out!