I figured I might as well start a project thread on the monstrosity that I'm planning to build. First, here's a screenshot of the current design in Inventor:
In that pose it's 550 mm long, 718 mm wide and 337 mm high. Weight is just short of 10 kg, and will exceed that since I may add more batteries and sensors.
* Make a good sized robot. 'Nuf said.
* Put my mechatronics engineering degree into practice. We also didn't learn as much in some areas as I hoped we would.
* Modularity for added functionality and ease of repairs/replacements. I have thoughts on a 6 DOF arm, a filament extruder and more. Did think about a laser cutter, but that would need a lot of planning and safety considerations. Probably won't do it.
* Allow for autonomous activity or manual control.
Breaking it down a bit further:
* Stable movement over a wide variety of terrain, including stairs. Using this outdoors would be nice, but could get very interesting...
* Enough grunt to carry a multiple kg payload (see modularity goal) at a reasonable pace
* Easy to replace legs if so required.
* Reduce strain on hip servos, especially Hip-Pitch and Hip-Yaw
* Mounting points for additional modules. You can see the front one in the above image, 4 holes on the L-brackets at the front. Subject to change, but probably won't differ by much.
* Battery power to last at least 3 hours. This may be a pipe dream.
* Power management board. Seems like all protection circuitry is made for relatively low power applications (e.g. current draw limited to <20 A). Design for a custom one is going well, a problem will probably crop up though.
* Recharging station. So far, this is much more annoying than it sounds.
* Onboard brains. Eyeballing a FriendlyARM, Beagleboard or similar single-board computer. Will most likely need secondary boards to interface with sensors. Those will be AVR based.
* Sensor suite mostly undefined yet. Only thing I've designed into it are pressure sensors on the feet, and an IMU is practically guaranteed. Will most likely include a vision system, rangefinders and so on.
* Wireless communication. Most likely going to go for Bluetooth or WiFi. From memory the data transmission rates from XBees will be too low to stream video (may be wrong on this though). More and more single-board computers have WiFi though.
* Probably going to go for 3 DOF IK straight off the bat. Constrain Hip-Pitch servo so that the plane generated by the femur and tibia is normal to the ground, then figure out algorithms to use rotation in that plane later. Hello Denavit-Hartenberg convention...
* Would be neat to have some code to read G-code and transform it into robot movements. That'll happen after I make the filament extruder though.
Process plan is:
* Get all servos and mechanical components.
* Build chassis, leg joints &c.
* Build power management board, signal isolaters and whatever else I need.
* Buy single-board computer.
* Get computer to control servos
* Implement IK and gaits
* Make final decision on sensor suite
This will be very long, and probably pricy in terms of my wallet and sanity. At least I have a mill & lathe to work out the mechanical side of things.