To avoid the trouble of pouring another motor mount, we bought a new mount from the Robot Marketplace. It’s pretty nice, but pretty simple. It makes me wonder how hard it would be to avoid all this casting mess with a mill. A mill would be nice.

It’s interesting to see how far we’ve progressed on this project by investigating the mounts. We started off with some jigsaw’ed 2×4’s that clamped down with rubber sheets for friction. Many facepalms were had. Working on this robot was another educational experience.

It was like communicating with myself last summer and wondering why in the world I chose to do things the way I did. Axle too large? Hammer it in. Discount possibility things will have to be taken apart later.

Here’s a nice garage-spanning table I made with my dad as a bonus. It’s nice that we don’t have to work on the floor anymore.

Here are the failed attempts at shaft collar wheel hubs that sheared off during our previous run. We started with JB weld, moved to epoxy/gorilla glue? mixture, and settled with some extra strength epxoy. Still didn’t work.

However we have opted to mount the reduction sprocket directly onto the wheel. By the sheer weight of the things we were afraid the hardened steel would be impossible to machine with our inadequate tools. However, we found out that the inside is extremely soft most likely cast iron. Machining worked well, and this solution seems like a confident final solution to our wheel hub problem. It’s a wonder we didn’t think of this painfully obvious solution earlier. More facepalms all around.

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I worked at the urological department of UCI Medical Center as an intern for robotic surgery, and it gave me some ideas on how to improve robotic surgery and how to improve its cost effectiveness. For the multi-million dollar price tag, robotic surgery doesn’t currently do what it was cut out to do.

We have yet to see surgeons operating with near telepathic efficiency on patients thousands of miles away. At best it has only been a slight telepresence of a surgeon supervising operators in a faraway room. The Da Vinci robotic system is operated by a surgeon only ten or twenty feet away connected by wire.

Of course this is limited by the heavy and secured datapath that must be maintained over the course of the surgery to effectively carry out the surgery. But given the high speeds of information propagation these days, why isn’t telesurgery more popular? Surgeons should be able to operate in places too inaccessible or distant from their current location with near full effectiveness (with a nursing staff to match of course). And with some improvements in machine vision, maybe even fully robotic automated surgical procedures in the future.

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So here’s my first robot arm. I’ve had the CAD files done for a while, but I had no time to actually fabricate this thing until now during winter break. The 4-axis frame sans gripper looked like this rendered in SolidWorks:

The base didn’t  turn out as expected since acrylic is expensive and I didn’t want to waste any scrap. I substituted it with a smaller piece of acrylic mounted on some cut up 1×2’s. Yes wood, we meet again. The frame itself was laser cut out of one (surprisingly small) scrap of 6mm acrylic. The arm frame I designed isn’t exactly the strongest or most stable of all possible configurations, but adding steel servo supports was too expensive for my college budget. As a result the base rotation joint is unnervingly unsupported. I will probably need to add a shaft support later if this arm is going to make any fast movements.

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The four servos for each arm DOF are all Hitec brand servos. The gripper and the end effector servo are both from Sparkfun electronics. I was very unimpressed with the gripper. Nothing fit like the site advertised and the medium servo they said would fit needs to be mounted at a strange angle to even fit mounted on the gripper, which seems to be shamelessly taken from Thingiverse (or maybe it is the other way around, which in case I offer my apologies). Either way, the gripper is made of aluminum with decently strong construction, though it is pretty imprecise in its bearings. I won’t be doing any precision gripping with this particular effector.

I’m currently working on some air muscles too, to try to make a Festo style fin ray effect gripper out of molded Polymorph. We’ll see how that turns out later on.

The arm itself is under strain when the position is not exactly neutral, which may be a problem if the arm needs to hold its position for any amount of time. By the way the servos are humming, it seems like I will have to add some counterweight/spring neutralization of the arm’s dead frame weight. Mounting springs between joints would reduce the required torque output of the servos for holding off-centered positions.

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So how does this relate to robotic surgery/telesurgery? I suppose part of me at the end of last summer thought it would be cool to create a cheap/simple system that would require little data transfer and still be able to effectively operate on patients over long distances. This robot arm “might” have that capability, but I am highly doubtful the precision is even close to acceptable.

Future work: I plan to increase the functionality of the servos by modding all of them with the Openservo magnetic encoders. That way I can use velocity profiles etc. to make it all run more smoothly. I’m currently making a simple control system that uses potentiometers on a miniature scale version of the arm to puppet the arm. In the future I will use servos for force feedback. The potentiometers connected to an Arduino and an SSC-32 board I obtained for free from my lab’s clean out giveaway + some XBee’s + a cheap video TX/RX system might allow me to manipulate objects from a distance. That would be one step closer to telesurgery right? Maybe even mount it onto Spirit MK2 and have a nice military IED diffusing robot clone.

At very least, I’ve downloaded some industrial arm controlling software if I ever want to make five more of these things and start my own production line.

OR maybe even make myself one of those robot arm helpers Tony Stark plays around with in Iron Man. Oh the possibilities.

I’ve been interested in quadrupeds for a while, since my sophomore year of high school. Or maybe way longer than that, since I watched Zoids: Chaotic Century years and years ago. Riding a Liger Zero with Jager high speed armor was and still is a goal I strive towards (that and driving a tank).

My research for this semester is to design a hydraulically actuated quadruped with two motors. The motors individually drive the front or back legs, and can support the entire robot in the event of a motor failure. These motors are hydraulic motors from large-scale model airplane landing gear from some far away country, and are extremely expensive, at over 600 dollars each (Cornell funding).

My design as of now looks like this:

Once again with the 3D render option in SolidWorks, making it look like a commercial for an Apple product.

The legs use cylinders, though I would one day love to expand to hydraulic muscles. Those four blocks are the valve manifolds that are servo actuated. The entire chassis will be 3D printed on the standard commercial extruded plastic printer, while the precision parts for the valves will be printed on the UV resin Objet printer.

Maybe if I study hard enough in school, and with enough time, blood, and sweat, it will someday look like this:

So I went to the Maker Faire with my project team to show off our latest Fab@Home work. Though I have followed the progression of the MAKE culture for some time, I never really participated in any of their events. I always wanted to visit a Maker Faire to participate in the combat robotics events, but never had the chance.

3D printers everywhere. The RepRap and the MakerBot really have progressed in popularity since their beginnings a few years back. I was impressed by the sheer number of emerging competitive systems that are constantly adding to the amateur 3D printer culture.

Our project boasts the ability to be more than a 3D printer. We have milling, hot foam cutting, both cold and hot extrusion, and 2D scanning on our bot. Hopefully, by developing our Fab@Home as a platform for tools rather than specializing on 3D printing, our product will appeal as the superior maker’s tool.

I’ve personally been working on displacement tools (squeezing stuff out of syringes), milling, and ice  printing. For the ice table, I basically freeze water on a plate cooled with liquid nitrogen and build up structures. The appeal of ice is its low cost to create molds/temporary models.

The Maker culture is pretty charming (see the singing seafood art car or the flame-breathing dragon). To me, it seems like a more conservative, technical version of the art displays that go on display at Burning Man (though I’ve never been to one myself so no true opinion).

As for 3D printing, I’m personally going to get into bioprinting very very soon. I want to print living cells and stack them into tissues and eventually organs. Though my bioengineer days are past me, I can’t simply abandon the appeal of growing organs from nothing. It’s some sort of Victor Frankensteinian fantasy. Cybernetic organs interlaced with electronic equipment, fully grown kidneys and livers regrown within days, biological self repairing printed living bone structures. It’s all too much. 3D printing is just way too cool.

Last spring semester (2011) I made this pan/tilt setup to mount a turret for Mech Warfare. It’s been stagnant for a while but I might be able to buy the airsoft tank cannon soon. I have an incredibly small 150′ range camera system set up so I might be able to test the full setup soon. However, I haven’t worked on the hexapod for a while as I don’t yet have the funds to buy the nice Dynamixel servos I wanted to use. Hobby servos just won’t cut it for me for a walking robot.

Mechanically, its based off the ServoCity pan/tilt system made of ABS. I made this one out of blue laser cut clear acrylic scrap, and modified it to use the lazy susan turntable as reinforcement for the pan servo axle.

Some time next summer after I’ve gotten used to programming quadrupeds I might consider rebuilding that hexapod for competition 2013. Control is shaky on the standard RC airplane transmitter, and hopefully serial control with the SSC-32 might be better. However, I used some pretty cheap Towerpro servos from Hobbyking for this pan/tilt, so I’m not really confident in the lifespan of this pan/tilt. Hey, at least they were cheap.

With my digital camera taped onto the mounting platform.

There it is. The rebirth of Spirit MK1. It is essentially a moving DDR platform box on wheels as of now. Our old solid steel frame was way too heavy and extremely overbuilt. It was good welding practice, but that old one piece frame just didn’t like to be modified. We tried to change that with our second frame iteration. This frame was made from 1″ aluminum square bar that we initially planned to braze or weld together.

The only welder we encountered was some random guy standing in line behind us at the metal supply store, and our HTS-2000 (advertised to be “stronger than the surrounding material”) failed miserably to stand up to any impact tests. and thus, the bolting began…

Six bolts per corner, three module boxes (drive left, drive right, and center) totaling hundreds of bolts. After we put it together, it started vibrating apart. Assembly number two included hundreds of tension washers. I would not be surprised if the added weight of the steel bolts has negated any weight/strength benefit from using aluminum, but at least the frame will stay shiny without sealing now. Our goal was simply to make the new config drive, which is what we did.

If you look closely you can see three cast motor mounts. Yes! They were a success. However the last mount took forever to make (too many unsuccessful pours) so we might just buy an official motor mount to compensate. On the bot is instead one of our unsuccessfully poured motor mounts. A permanent solution can wait.

Otherwise the configuration is relatively similar to Spirit MK1. We have divided the robot into functional sections. The drive modules just include the transmission. The center module will house the batteries, motors, and electronics. A separate weapons module will be installed at the front/top, while armor plating will cover the exposed sides.

We spent quite a bit of time attempting to make hubs that would effectively restrain the wheels to their axles. However, most of our attempts have been failing. For this iteration, we attempted to double epoxy two shaft collars (that conveniently are the same diameter as the wheel bore) to transmit the torque. After a successful run and rounds of cheering, the robot attempted a tank steer while beached on a rock (we built this thing with low clearance to avoid wedge attacks). The stall was enough to shear off some of our temporary wheel hubs and left the wheels to freely spin.

It will have to wait until winter break however, I’m going to start school soon.