The idea is to make an initial 1/4 scale working model (v1) with as many off the shelf parts as poss. Which means the esthetics will not be a consideration. I will aim to make the components of v2 more realistic - but that's to come.
The aim is to replicate and button down the kinematic performance that was simulated - shown in the enclosed video. This will use minimal electric controls and no autonomous capabilities. Electronic controls will be integrated in v1.1.
v1 will be limited to electro-mechanical components and controlling axis motion by a 4ch RC; frame extension/retraction with limit switches, independent wheel drive (channel each side) and rocker-bogie extension/retraction. Frame folding will have manual DPDT switch with limit switches.
v2 will incorporate specifically designed beams, posts and and various other components, with a first pass at incorporating arduino control systems to to make it terrain aware; vision and LiDAR integration to make more autonomous in traversing uneven and rough terrain.
To expedite v1, will minimize design and making of parts - extremely time consuming. After reviewing a number of robotic supplier sites, opted to source approx 90% of the components for the model from ServoCity. Their range of actobotics components makes things simple. (Gotta plug'm - i was very impressed with their site layout - logical, content organized, clean layout and easy to follow - so much easier and nicer than others -in addition, have a great lib of product/part demo videos - highly recommend.) But there is something they could work on, adding multiple wishlists - would make ordering by sub-assembly so much easier!) As subsequent project pics will show, they take the hard out of robotic prototyping!
I will also be making numerous 3D parts - well, over 200 deck hinges and post attachments, along with laser cutting 20 decks. These will make as realistic as poss as i hope to re-use in the v2 model.
Update - 01-07-17
Per last photos, V1 mechanical model is close to complete. Some learning and takeaways were found with the present design and some components. The two wheel design rocker-bogie configuration was found to be inadequate - without the third wheel support, it puts excessive load on the shaft couplings and unnecessary longitudinal loading on the scissor frame. To ameliorate the impact, will add third wheel to rocker arm for a standard configuration.
As seen in the photos, the initial frame was made mostly with plastic scissor beams - these are not rigid enough, lacking longitude and torsional strength, as seen by the bowing of same in the pics. Will change these out for all aluminum beams, same as first scissor unit in model.
The frame cam that lifts the frame at the end of retraction has gone through numerous alterations to find the right profile and lift characteristics - think it's close to final. All 3D printed parts are made of minimal fill to test placement.
The preliminary decks are rough cutouts which serve to test extension and retraction dynamics and confirm hinges will work adequately - so far so good, but the final decks will need to be cut with laser to ensure tolerances are met.
With the completion of the mechanical modifications will start on the elector-mechanics.
Update - 01-25-17
Latest pics show the replacement of the scissor beams with aluminum ones which fixes the bending and torsional issues experienced previously. An Al rocker arm was also added to the wheelbase with respective wheel and motor to provide greater structural stability. Modifications were also done to the frame/shaft coupling - converting from single to dual axis pivot - releasing considerable loading on the frame and improving respective kinematics. The frame cam lifters were also replaced with final designs - however, still experiencing control issues in the lift motion due to the newly added free 2-axis frame/shaft coupler.
With the mechanical structure mostly complete, I have begun the...Read more »