Firebot mechanical parts (2)

In the last post I talked about the design requirements. In this post I’m going to talk about what we’ve ended up with.

So – here are the (more or less) final mechanical parts:

The ladders hold a “sensor block” which mounts the forward-facing camera.

The front “bumpers” are removable with dovetails to lock them in place. This allows for easy changing of the accessories for different events.

The central section of the cab is removable to reveal the channel for storing barrels and mounting the Nerf gun. Here is the robot configured for Eco Disaster:

Those strange keyhole cutouts at the corners are for holding the magnetic rotary encoder PCBs in just the right spot to read the magnet mounted on the brushless motors that Shaun’s worked so hard on.

The front of the chassis and the rear of the chassis are in two parts, with a pivot between them, allowing the front and back wheels to twist relative to each other. This is to ensure that all 4 mecanum wheels touch the ground (for small amounts of unevenness). The pivot is restricted to about 10 degrees of movement. Mecanum wheels (when moving in some directions) rely on the forces produced by opposite wheels to cancel out – this can only happen if they’re all touching the ground. If one wheel isn’t touching the ground, you can get unintended rotations of the robot.

Here’s a view of just the chassis parts, with the pivot point highlighted in yellow. An M5 bolt, washer and nyloc nut go through that pivot to connect the chassis parts.

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