pic: Offseason independent swerve design concept chassis

[apalrd]

It looks like you're relying purely on material stiffness to prevent bending, and not section. This is a very heavy approach.

A better way is to design in flanges and box/geometric sections in some way. In sheet metal, this is done with flanges, in a tube frame, this is done with box, C, and angle channel. You will handle the loads much better in this way.


Basically everything in the chassis design is unsupported, and there will be extremely high bending loads on virtually every component. I recommend re-evaluating your construction methods and load paths.

What all of this means:
-Think about where you would place a mechanism on this. Where is it loading the frame? Say it weights 60 pounds. Where are those 60 pounds going? If we assume the mechanism is a point in the middle (worst case), the only thing to support it is the plate aluminum, which will likely bend. The only thing preventing this are two braces in tension on the sides, which are attached to the red boxes, which become a large lever arm, which is likely to bend the connection to the top plate (over time or rapidly, depending on material thickness and connection methods).

Consider an alternative design:
-If using sheet metal (I <3 sheet metal), consider forming a chassis panel on all four sides around the pods from top to near the ground, flanged inwards on the top (and inwards or outwards on the bottom, your choice), and attach the pods to these flanges. Then run two chassis panels down the middle to pick up the inner sides of the pods, with four additional smaller panels to pick up the fourth side of each pod (does this make no sense)? Since this is a swerve, torsional stiffness isn't as important as in a drop center drive. With this, you could use an HDPE disc near the axle of the pod to transfer side loads into the sheet chassis better, reducing loads on your upper bearings (allowing you to design them differently/less beefily).

-If using box or channel, I recomment a similar layout but out of 1x1 box tubing directly under the support plate for the pod. This will provide enough stiffness in 1/8" (I'm not good at the mecanical analysis, I'll leave that out), and would probably work in 1/16" with additional stiffness from the mechanisms. From there you could bring back the red risers (1x1 box) and run another box around the perimeter out of 1x0.5" L,C,or box. Make sure you don't cut the flange to retain stiffness, that is important. You can also triangulate the risers to the upper frame, you will want this if your bumpers are attached to the lower frame.

Try to design around stiffness by sections. This starts with using panels/tubes with sections (folded sheet metal vs unflanged, box/C/L tube), then making larger geometric shapes with the structure (triangles are especially strong, boxes are strong but possible to turn into parallelograms, etc.). Then think of the load paths, where the large forces are coming from, where impacts (bumper loads) are going, where gravity is supporting the robot, etc.