SAM NIKOLSKY

CO

NC

EPTS

Using a focused laser beam to create plasma, images can be

displayed in the air.This volumetric display, coupled with motion tracking allows the user to sketch a form in the air, and have it displayed in true 3D

as it is being created

Based on magnetic levitation technology, MagLev Sufacing is a three dimensional tangible interface for creating 3D surfaces.A planar array of magnetic spheres with each individually contolled on 3-axies creates a surface that can be manipulated, and allows the

form to This concept involves the coupling of motion tracking with an array of LEDs. As the user sketches in the air, their movement is tracked and is displayed with each light acting

as a pixel.The light cube can be a sculptural piece where the public can interact with it and create ʻartwork within

an artworkʼ

Using Fused Deposition Modeling techniques, this concept allows the user to create a form freehand, and have the same form recreated by a

CNC machine.

A pantograph is a device traditionally used to copy and scale drawings. The Digitap Pantograph combines motion tracking with a CNC machine, allowing the user to trace or copy a 3D form and have the actions mimicked by the machine. This allows the reproduction of forms as well as the

ability to scale a model.

Sketching is an important technique for artists and designers to use in the generation of new forms, and in the expression of ideas. Traditionally, sketching has been restricted to two dimensions, with a tool such as a pen marking a medium i.e. paper. Through investigating existing practices and emerging technologies such as 3-D printing and gestural tracking the research will explore the possibilities for the user to create a three-dimensional object or form from only an initial sketch.The end result may be a physical object that is created by the skill of the user. This object can serve as a rapid prototype generated in a matter of seconds, or a refined, finished sculptural artwork crafted by a skilled user

over a number of hours. This research will draw on similar technologies and past projects to determine strengths and weaknesses of each, as well as experimentation with different materials and processes, create prototypes, conduct user testing. The research will explore possible applications of this tool, from design to jewelry to fine art.This tool will draw on technologies found in computer-controlled devices whilst allowing the user to create forms with a ʻhumanisticʼ element to them. This application of skill combined with the technologies will produce an object with similar physical qualities to one produced with rapid prototyping machines whilst retaining qualities of craft.

TECHNICAL IMPLEMENTATION The current prototype comprises five key elements as illus-trated in figure 4.

• A magnetic levitator (a coil driven by PWM sig-nals) that suspends a magnetic object and is capa-ble of changing the object's vertical suspension distance on command.

• A 2-axis linear actuation stage that laterally posi-tions the magnetic levitator and one additional lin-ear actuator for moving the coil vertically.

• Stereo cameras that track ZeroN’s 3D position. • A depth camera to detect users’ hand poses. • A tabletop interface displaying a scene coordinat-

ed with the position of the suspended object and other objects placed on the table.

Untethered 3D Actuation The ZeroN system implements untethered 3D actuation of a physical object with magnetic control and mechanical actu-ation. Vertical motion was achieved by combining magnet-ic position control which can levitate and move a magnet relative to the coil, and mechanical actuation that can move the entire coil relative to the entire system. Two approaches complement each other. Although the magnetic approach can control the position with lower latency and implies promising direction for scalable magnetic propulsion tech-nology, the prototype with pure magnetic controls demon-strated limits in its range: when the permanent magnet gets too close to the coil it becomes attached to the coil even when the coil is not energized. 2D lateral motion was achieved with a plotter using two stepper motors. Given a 3D path as input, the system first projects the path on each dimension, and linearly interpolates the dots to create a smooth trajectory. Then the system calculates velocity and acceleration of each axis of actuation as a function of time. With this data, the system can actuate the object along a 3D path approximately identical to the input path.

Magnetic Levitation and Vertical Control We have developed a custom electromagnetic suspension system to provide robust sensing, levitation, and vertical

control. It includes a microcontroller implementing a pro-portional-integral-derivative (PID) control loop with pa-rameters that can be set through a serial interface. In partic-ular, ZeroN’s suspension distance is set through this inter-face by the UI coordinator. The PID controller drives the electromagnet through a coil driver using pulse-width modulation (PWM). The field generated by the electro-magnet imposes an attractive (or repulsive) force on the suspended magnetic object. By dynamically canceling gravity by exerting a magnetic force on ZeroN, the control loop keeps it suspended at a given distance from the elec-tromagnet. This distance is determined by measuring the magnetic field immediately beneath the solenoid.

Magnetic Range Sensing with Hall-effect sensor Properly measuring the distance of a magnet is the key component in stable levitation and vertical control. Since the magnetic field drops off as the cube of the distance from the source, it is challenging to convert the strength of the magnetic field to the vertical position of a magnet. To linearize signals sensed by the hall-effect sensor, we devel-oped the two-step gain logarithmic amplifier. It logarithmi-cally amplifies the signal with two different gains, based on whether the signal exceeded a threshold voltage value. Designing ZeroN Object We used a spherical dipole magnet as a levitating object. Due to the geometry of magnetic field, users can move the spherical dipole magnet while still keeping it suspended, but it falls when they tilt it. To enable input of a user’s de-sired orientation, a loose plastic layer is added to cover the magnet as illustrated in figure 7. Stereo Tracking of 3D position and 1D orientation We used two modified Sony PS3Eyecams1 to track the 3D position of ZeroN using computer vision techniques with a pair of infrared images as in figure 8. To measure orienta-tion, we applied a stripe of retro-reflective tape to the sur-face of ZeroN. We chose this approach because it was both technically simple and robust, and didn’t add significant weight to ZeroN: an important factor in a levitating object.

1 http://codelaboratories.com/products/eye/sdk/

Figure 6. A simplified version of the magnetic range sensing and levitation circuits.

Figure 5. Mechanical actuation combined with magnet-ic vertical control enables 3D untethered actuation of an object.

Light Painting Cavepainting Spatial Sketch Sketch Furniture FreeD