Quadruped Robot: Adapting the Chassis…

Okay, after tinkering with the controllers, I managed to find out the Dagu Mini is actually an Arduino Mini, I think, with ADC inputs and 8 servo PWM outputs and a couple of motor drivers all built in. So in all, a pretty neat little solution. However, I realised I’m going to nee more that 8 servos – 2 for each leg and another two for the head gimble. So I decided to stick with the Hobbytronics Servo driver boardr, as with 16 channels it has more than enough output for my requirements, and I can communicate with it directly over i2c.

So let’s talk about progress in the last few days…

First off, I know most people produce videos these days for this sort of thing, and that’s probably more efficient. But you know what? Screw you, you lazy millenials – you can read this.

Where to start…? Well – I had to redesign parts of the robot. I widened the shoulders, and added a couple of struts to connect them so I can screw the whole thing together and it be rigid. This was to so that the battery pack can fit, but even then it’s a bit tight, so I may go back to the drawing board at some point to try and get all those measurements perfect.

New chassis with wider shoulders and a longer body. Beats the crappy lolly sticks I was using.

Same with the legs. I didn’t factor in any tolerance for the 3D printer so I had to bore out the servo mounts a bit and glue them to the servo shaft which isn’t ideal as it doesn’t leave me with the ability to adjust anything.

So I printed this:

My custom servo hole tester.

It’s a test block with holes that increase in 1/2mm increments so I can test out the optimum size for the holes, that way I know what size to adjust them to when printing out new legs. More on that later.

So this is what we’re left with:

Sorry about the shitty photographs. I’ll get something decent set up, but my workbench is embarrassingly small and I’m not the tidiest of worker…

Next up – Inverse kinematics. I hope you like maths.