Thursday, April 19, 2012
Boris the chain bar robot (Boreus Hymalis)
I was in Barcelona Spain when I got a funny email from my good friend Jonathan who asked me to see about bringing some robots to an event called "Smukfest" in denmark, the email subject read: "robots for drunken dains". I could not resist responding but I was at a loss as my robots were all booked for the dates surrounding that event. So I proposed to build a new robot that I had bonking around in the back of my mind ever since I acquired a mid 70's Case/Davis track force 700 tracked trenching machine off of craigslist for $500 bucks. So began a two month build of the coolest robot ever.
Starting with 30 year old machinery always presents a pile of extremely challenging problems. I had to start with the first problem of replacing the original clutching track control differential. The Davis machines use a fairly traditional system of two clutches one for each track and a reversible hydraulic pump, I knew of course that this was inherently flawed and hard to fix if it broke and really hard to control via RC systems. So the plan was to use two large hydraulic wheel hub motors from dead scissor lift I salvaged years ago and use the torque tube they mounted to. Unfortunately my seemingly convenient motors were too long to use as the track drive and I had to buy a set of 500ftlb 2000psi rated hydraulic hub motors from surplus center. I then had to design the hub adapters for the spline shafts that the track sprockets keyed into and thanks entirely to Dave Andres who made the large steel adapters for me I was able to complete the hydraulic differential conversion with a high measure of success: damn thing worked like a charm!
It was a relief to finish the differential conversion, but my confident attitude was smashed when I began the long processes of designing the complete hydraulic system. My challenge was simple on paper but seemingly impossible in practice: design a four signal hydraulic electric radio control system based around a 48vdc 500amp Raymond hydraulic pump using spool valves for the tracks and electric valves for the chain bar motor and the chain bar actuator. NOPE!! After dead heading the pump thus stalling the DC motor using electric valves and completely fragging my hydraulic pump I went for manual servo controlled valves on the chain bar and a double stage hydraulic pump I was able to at the very last minute cobble together a functioning robot that could drive and dig ditches at the control of my Futaba 14mz transmitter.
Making its debut on youtube Boris howled to life naked but functioning, his DC hydraulic pump cranking out a comfy 150 amps at 48volts DC (7.2kw) not bad for 2500lb beast of steel lead and iron. Boris was alive!!
Once the movement was established it was time to start thinking about what Boris would look like as a sculpture, that lead me to use Steve Valdez's pipe rolling machine at American Steel. I decided to keep it simple, I came up with a radius that I liked and just rolled about 10 20' steel pipes figuring that the shape and feel of the robot would come into its own once I started placing the rolled pipes around the robots core. And enter Lex. Lex showed up just in time to help me place the pipes and get them tacked into place so I could step back and observe the piece in totality. And the shape continued to form in front of me. Once I had established the over all shape and feel of Boris sheeting and decorating his outside skin with some help from Evan and Jordana soon he was a tracked art piece and not just a naked metal robot bent on destruction but a fully dressed robot bent on destruction!
So Boris was born into world scared of its own shadow and numbed by TV, a world about to have its reality rocked by a robot so unusual and unique only to be shoved into a 20' container and sent off to Denmark.
Boreus Hyemalis by Justin Gray from Mike North on Vimeo.