I did a bit of tinkering with strut configurations last night and decided to jump right in and go with a 3DOF plus steering setup.
I'm going to try a dual ASB-11 setup between the "knee" and "tibia" joints rather than using "C" brackets there or a "C" and ASB-11 setup. Next week, I should have the rest of the brackets and tubing to complete construction of two of these hybrid legs. I think I have enough servos to fill two of these assemblies, and at present am planning to use HS-645's in the two heavy lifting joints and HS-475's for horizontal movement and wheel steering.
If this all comes together the way I hope, WALTER will be in a two wheel plus caster setup. In this setup, the strut/legs will be added on the chassis points each side of rear center and the caster will be on the front center point. I also have an HS-475 installed on the front center point for a pan/tilt sensor platform with a Sharp IR and PING sensor.
As for motor controllers, I am planning to try out two of the RoboClaw 2x5A
controllers which can be operated from a single UART and has dual quadrature motor decoders built in. Hopefully I will be able to get two of these next month. In the meantime, just to get things running, I'll fall back to my Sabertooth 2x5 just for motion and possibly use the Webbot routines for quadrature decoding.
I just have not chosen the wheels and hubs yet, but am hoping to start out with the ARW-01
wheels and an appropriate hub.
As for controllers, I will bring my Society of Robotics AXON (Atmega640 based) into service. It has 3 additional UARTs in addition to one dedicated to USB. I will use one UART for an SSC-32, one for motor controllers, and one for XBee wireless. It's too bad the AXON has all but 16 I/Os wired for direct battery power. Only 16 I/Os (analog and digitial capable) are wired for 5V use.
For now, the AXON has the I/O and memory (64K flash) I need to do what I want to do with WALTER. I've already got the AXON working with Sharp IR and PING sensors and, thanks to the Webbot library, things are quite easy to do.