Compatibility Standards in Hobby Robotics

Compatibility Standards in Hobby Robotics

During our last competition this year, I saw non-TETRIX MAX parts on some of the other schools' robots in every category.  That sparked the compatibility question and The coach, Mr. Courdway mentioned that someone had tried something the year before that came from outside the kits and the holes didn't line up.  So this begged the question...what are the standards for the different levels of robotics and what works together.  I am going to run through the major brands and finish up with scratch building.  

I might as well start with PITSCO TETRIX MAX.  This is the brand name on our educational kits and they use a metric flower pattern for their mounting arrangements.  

This pattern allows for the connections between structural components, servos and motors in arrangements that generally allow a great deal of flexibility in design as long as it stays withing the 45 degree constraints.

Next is a close match, the Actobotics system.  It features a pattern based around SAE measurements and has patterns at .770" and 1.50".  

As you can see from the diagrams above, they are not directly compatible with TETRIX MAX without modification.  That does not mean they should be discounted.  Actobotics has some great components that can enhance any build.  

Another fairly popular brand is Lynxmotion Servo Erector Set.  It has some very popular components and provides some solid servo capabilities.  The Servo pattern is first followed by the two structural patterns.  TETRIX uses a variation on this pattern.

Servo Pattern

Lego Mindstorms are built around the regular Lego brick pattern, but Legos makes an adapter that will allow you to add Mindstorms components to other systems.

FIRST/Colson was developed by FIRST and is not often seen.  VEX Pro, AndyMark, and Nexus use the pattern on some components and perhaps a few others that seek acceptance by FIRST.  

VEX uses a square mounting pattern for all components and offers no compatibility across platforms.

It is possible to hack the VEX components if necessary, but it is often a better proposition to get the components from another more compatible source.

Here is a comparison to all described patterns:

The final pattern of note will be motor mounting bolt patterns.  Various manufacturers use the following front mount pattern for their Spur Gear Motors:

Scratch Build or Part Modification

Assuming we will be building our robots using the TETRIX MAX base components and seeking ways to modify other parts to function with the TETRIX base.  LynxMotion is the closest pattern and Actobotics pattern allows a lot of cross use for the components of each.  

Another alternative is to get relatively inexpensive aluminum stock and drill the holes for the bolts int0 it.  This requires a drill press, a good set of metal drill bits and saws, and possibly a small metal brake.  additionally clamps and taps and dies would assist in the manufacture of specific components to complete your robot.  Here is an Instructible that illustrates the process.

https://www.instructables.com/id/Double-Drill-Channel/

Additionally, the information for this post was gathered from the following sites:

PITSCO.com

ServoCity.com

Lynxmotion.com

FIRST

https://www.robotshop.com/community/blog/show/hobby-robot-industry-standards-hubs-amp-mounting-patterns