Kevin Gray

Air-Operated Ball Levitation Mechanism--my patent model - This air levitation mechanism was used as the basis for the Harry Potter Levitating Ball Challenge game. The control wheel on the left moved the ball around the disc, while the lever on the right controlled the ball's hover height. I am co-holder of the patent that was issued for this mechanism. The motor and most of the air mechanism is stationary and does not move; the 3 moving parts of the air pump are the fan disc, air duct, and control vanes under it (see a sketch in Working Drawings).

Scoot So Cute crawling doll mechanism - This was a mechanism designed for the Scoot So Cute production doll. The arms and legs moved in a realistic manner to make the model crawl, and the head moved from side to side while crawling. The model was radio-controlled for ease of operation and testing. The doll's head can pivot forward 90 degrees forward and still move side to side; it is locked in place in its forward and back positions via magnets.

Scoot So Cute crawling doll mechanism--adjustable parameters - The mechanism was designed to allow changes to be made to the throw and phasing of the arm and leg motions, and the length of the body could be increased by 1.25 inches. The view here shows the torso at fully extended length, with reference marks for the extension and the left arm phasing adjustment. Setscrews allow quick changes. These adjustable parameters built into the mechanism allowed the most realistic crawling motion to be determined, as well as the optimum length of the doll.

Mechanism partly disassembled - The right-hand body panels and animation components have been disassembled in this view, showing the adjustable-length link that moved the rear leg, and the eccentric brass disc that drove the right arm. The drive servo had failed, and needed replacement. Because of the modular way in which I design and build my mechanisms, disassembly and repair was easy to do.

Liv Twist & Dance mechanism prototype-exploded view of mechanism - This is a photo of all of the mechanism's parts. There aren't many bits, which is just as well--there isn't much room in there.

Liv Twist & Dance mechanism prototype-parts - A closer look at the mechancal bits inside the prototype's body.

Servo driven gearbox and mechanisms - This is a servo-based mechanism that animated a doll model. The servo was modified to act as a bidirectional gearbox with proportional speed control in both directions. The gearbox acted as a gear-up stage, speeding the output of the servo up by more than three times. A kardan-like brass drive coupling compensated for slight misalignment, eliminating binding if the gearbox was flexed. The upper servo controls the motions of the arms via custom-made SLS miter gears.

Arm drive mechanism via servo - The arms were rotated in opposite directions by the three miter gears, driven by the servo in the lower area of the torso. The arm sockets contain springs that pull the hemispheres on the arms into the sockets. This creates enough friction that the arms can be positioned and then moved by the servo without losing their pose.

This is the prototype for the Cupcake Barbie project, showing the doll's mech internals and the cupcake in its uneaten state. The action desired for this prototype was for Barbie to "eat" a cupcake she held in her hand; the cupcake would change state from "Uneaten" to "A big huge bite taken out of it" when it was raised up to near Barbie's face by raising her arm. It would then magically change back to "Uneaten" as her arm was lowered back down. In addition, her head was to incline slightly towards the cupcake when it was at its highest point, as if she was taking a delicate bite. I came up with a way to use magnets to do the magic; the top of the cupcake was built to pivot on a small internal axle. The two sides were then sculpted to be 1) whole, and 2) chomped.

There were magnets everywhere on this model; three magnets in the cupcake (two of them to create a 180 degree magnetic detent so the top would stay in the state it was flipped to), and two magnets in Barbie herself, one in her chin, and one in her chest (visible here). I couldn't think of a simpler way to flip the cupcake top; running a wire through her arm (and bent elbow) to move the top seemed to be painfully complicated at the time. Were I to do it over, a cord threaded through her arm that worked in tension to flip the top might have worked, instead of the pushwire idea that scared me into using the magnets...

Here the cupcake top has just flipped over to show the "eaten" side, driven by the magnet in her chin.

It's more apparent here that Babs has just taken a big honkin' bite o' cupcake!

And suddenly, it looks like she never touched it, as the magnet in her chest flips the cupcake's top back to the unbitten side. "I didn't eat a bite! See?" The magnets would allow as much eating and denial as one would want to indulge in. Sadly, the production model displays none of this action, as it was edited away for production. Instead, Barbie holds a cupcake on a plate, and moves it as if to mash it into her face as you raise her arm. She doesn't "eat' anything, the cupcake stays the same up or down. Such is life, I guess.

Flakpanzer Gepard super-animated R/C model tank (nickname GIZMO) - I have designed and installed multiple animation systems on this Tamiya Flakpanzer anti-aircraft tank to create a super-animated model. The model has twin strobe tubes in the anti-aircraft cannons (with sound), variable drive speed and diesel engine sounds that track with the motor speed, self-deploying and stowing radar systems, and working head, tail, and brake lights. The turret can slew 360 degrees at high speed, and the forward fire control radar tracks with the angle of the cannon.

Flakpanzer Gepard model, AKA GIZMO, interior with hull removed - GIZMO is literally packed with electronics and mechanisms for the various animation and sound effect systems. The model is at the point where there is almost no more room for additional efrects to be installed. But, I am going to install a wireless color videocamera in the Fire Control radar, as well as a pair of visible red lasers to simulate the real tank's infrared laser rangefinder. There's still a bit of space in the turret, and having telepresence on this model would be so cool...

CadZZilla engine shaker and hood release mechanism - This view shows the cable-operated hood release arm. The release system worked by pulling the steel pin in the arm down and away from a disc magnet hidden in the spring-loaded hood, which then popped up. The mechanism that would either open the hood or doors was located in the trunk.

CadZZilla engine shaker and hood release mechanism - The firewall has been removed to show the engine shaker motor and worm gear, and the magnetic hood release latch. The engine shaker would move the engine from side to side, in sync with the increasing or decreasing speed of the engine sound on the audio track. The real engine of the Cadzilla was recorded and used on the audio track for complete authenticity.

Bi-directional gearbox - This gearbox used a single motor to release either the doors or the hood by reversing the direction of the motor. The gearbox used a double worm drive to enable the gearbox to fit in the CadZZilla's small trunk, and to get enough torque from the tiny motor to run the features. A wobble gear was used to separate the two gearbox outputs; the cable that curves around the motor goes forward to operate the hood release. The arm on top of the gearbox pulled release pins back to open the doors.

CadZZilla door release mechanism - The steel pin visible in the door jamb was pulled back by the release mechanism in the trunk, which allowed the spring-loaded door to pop out slightly. There was a magnet mounted in the recess visible in the door which, when closed, touched the pin and held the door closed. Both doors were held closed with this magnetic latch system.

Film-Based Mechanical Flight Simulator Game - This prototype was a mechanical flight simulator game; it was based on two shutterless 8mm film cartridges linked by a common drive system. The images from each unit were back-projected on the viewing screen. Similar in concept to the dual LaserDisc based arcade game Dragons Lair, this prototype would switch between the two film loops by turning on or off each unit's projector bulb. The game involved flying between buildings, and moving the control stick at the rignt time to avoid a crash.

Mechanical Analog-Digital Teaching Clock - This mechanical teaching clock was designed to simultaneously show both analog and digital time. The knob on the minute hand drives the mechanism forward or backward; the hour hand moves 1/12th as fast as the minute hand is moved. A shutter shows only the digital time that the minute hand is pointed toward, to avoid confusion. The mechanism is based on a 12 position Geneva wheel, and has only 12 parts.

Mechanical Analog-Digital Teaching Clock--2:00 - The prototype now shows 2 o'clock.

Mechanical Analog-Digital Teaching Clock--2:20 - The prototype now shows 2:20. A small detent clicked at each of the 12 positions of the minute hand.

Mechanical Analog-Digital Teaching Clock--3:35 - The prototype now shows 3:35. Since the clock's mechanism was driven by the child, no batteries were needed. However, it would have been a simple matter to program a chip to play various sounds and phrases for each position of the hands.

The Happiness Machine, a "mood projector" mechanism - This machine was built for an Honors sculpture course; the assignment was "create a machine that made the viewer happy". Designed to be experienced with one's eyes closed, it projects the feeling of being in front of a campfire at night, in a pine forest, with someone softly playing a guitar. The machine projects pine and smoke aromas, flickering light and IR heat, and a stereo soundfield of a forest (and guitar) at night. The mechanism was cam-controlled; simple but effective.

Thunder Tracker drive system - View of vehicle's drive system. System uses simple compound acetal spur gears and a 3V Mabuchi type electric motor.

Experimental vehicle drive gearbox - This reduced-volume gearbox was designed to fit the area where the stock gearbox was mounted. A new gearbox was needed to change the vehicle's speed in support of the objectives of the research program.

Solar Crawler mechanism - This was a quick model made to test a concept for a solar-powered toy. The amorphous solar panel on top powered the model when placed in sunlight. It is 4-wheel drive, with a pivoting suspension system (borrowed from a production toy). Speed was about 4 feet per minute. The model was later modified with the addition of a small rechargeable battery, so it would keep moving if the sun went behind a cloud (or your hand).

Solar Crawler, climbing over obstacle - The 4-wheel drive and suspension system meant that the crawler could climb a 45 degree slope--as long as the solar panel had light. This concept was explored to see if a vehicle could be controlled by shading the solar panel(s) on its top with a hand--a very simple method of remote control.

Homebuilt solar tracking array - This is a homebuilt equatorial tracker, built to hold five Siemens M55 PV panels. The 250 watt array charges a pair of T-105 flooded call batteries through a 12V Morningstar charge controller. A 12VDC to 120VAC 1200 watt sine-wave converter supplies power to all rechargeable power tools and yard equipment (string trimmer, lawnmower, leaf blower, etc).

Tracker slew motor compartment, open - View into tracker slew motor compartment.