Since I’m home for Christmas break, I’ve spent the last week or so building things out of Vex IQ.
This is the first version of an AWD car. I started designing it to find a use for the VIQ universal joints, and spent a few iterations designing the outboard package. I started with a front outboard package (with steering), and the first-gen rear package (the first 3 images in the album) is shown prototyped.
A prototype of the outboard package:
I went through a few revisions of the control arm geometry, the rear is simple and stiff but the front needs more complexity to allow steering. I’m not 100% happy with it and the next version will be redesigned.
It’s designed for 3 differentials (2 are done so far), for all-wheel drive from a single input with proper speed matching all around.
I’m open to suggestions on the front suspension/outboard package geometry, I’m still not happy with it. What I have now has a lot of bump-steer and bends a lot.
Link to an album with images:
The current state of the car:
I have been testing it with the Modkit code from my motorcycle, when I finish the powertrain I will write dedicated code for it and upload it.
It’s not really a practical drivetrain for a robot, but it’s very practical for a car, which often goes over bumps at high speed. I’ll try to take a video later today. The shocks do really work, on the rear they work well, but the front has bump-steer issues that I’m trying to sort out. In side view, it can go from 2" to 0" of ground clearance.
That’s a very car. The front wheel/steering setup is significantly less complicated than mine - but I was trying to keep it AWD and needed the half shaft to stay constant length through its travel.
This is seriously cool and something that is on my list to build for a project we have on the back-burner over here. The one thing I couldn’t get sorted in my prototyping was the steering arms - with no ball joints or way of simulating ball joints in a small space, I couldn’t come up with a way to let the steering arms pivot as it steers, but follow the hubs up and down as the suspension moves. How did you overcome this?
Just seen the pics on the album which make it clearer - will have a look to see if I can make something similar for our design.