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Bartlett School of Architecture, UCL

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Orbital Thresholds

Orbital Thresholds

A site specific installation for the UCL north Observatory, Orbital Thresholds is inspired by the mechanical movement of the Orrery. A tradition of exquisite kinetic models that describe astronomical orbits. A fascination with the science of visual spatial-perception has led the team to consider how projection can give the illusion of spatial transformation through light alone.

A multi-axis rotating mechanism constantly manipulates a reconfiguring projection system. Occupant behaviour is tracked and activates the motion of the system’s projection arms. Animated lines-or-shapes projected from the onboard lasers encourages  participant interaction and spatial negotiation. The public are invited to visit and explore through interaction, by how light shapes the boundaries between virtual and visual space.

How can people feel ownership and agency within a space, creating a transformative environment that responds to their paths of motion and gestures? Starting from the questions, the aim of Orbital Thresholds is to create a spatial experience from intangible space with laser projection. We will also explore how people relate to one another in these spaces. Using lasers, real-time tracking technology, a bespoke structure in the UCL observatory is being developed. People tracking tech is used to trigger intrractions between the virtual and physical.

survey co

Fig1. The site survey: UCL Observatory.

Version1: These figures shown below are the first prototype of the mechanism design of the interactive installation “Orbital thresholds”.

Key components diagram Fig2. Key components diagram.

holder structure

Fig3. Holder Structure.

The structure is fixed in the observatory ceiling. When participants move in the observatory, virtual walls and different patterns can be  created by the ‘wall maker’  according to participants’ movements and behavior.


Fig4. Render image.render4

Fig5. Render image onsite.
Parts of Prototype 01

Fig6. Parts of prototype 01.

The prototype is made following the shape of the observatory which is circular. The mechanism of orrery is applied to move each part that holds the laser pointer, galvanometer motor, detecting camera is fixed in the bottom part.

Screenshot 2015-04-09 16.36.48

Fig7. Generating virtual wall and pattern.

The illustration show the sequences of how the wall maker works. The rotation is the trigger and mechanism from the galvanometer motor are the key in transforming point into surface. With the help of fog machine, the virtual wall can be seen and give experience to people.

Screenshot 2015-04-09 16.45.49

Fig8. Prototype Model.


The effects: 1) Multi-laser projection. 2) Rotating Laser. 3) Dynamic projection

Screenshot 2015-07-18 16.28.13

Fig9. The effects of dynamic projected lines.

Possibility of cutting space with projecting lines: 1) Parallel lines. 2) intersect at different points. 3) Intersect at the same point. 4) Hydrid

Screenshot 2015-07-18 16.28.20

Fig10. Possibility of cutting space with projecting lines.

A scenario and effects shown (white: participants; green: projected lines):


Screenshot 2015-07-18 17.03.36


 Fig11. The effects photos in scenario.

In Figure 11, the axonometrical drawing of the core rotating part is analysed. One arm is driven by one stepper motor. Its function is to let the arm rotate clockwise and anticlockwise. In order to ensure that the arm can be balanced and the rotating function can perform well, a spherical roller bearing (no.7) and a thrust bearing are used on the top and bottom of the rotating core part. Spherical roller bearings are self-aligning and are therefore insensitive to misalignment of the shaft relative to the housing and to shaft deflection or bending. At this point we need to reassure that the whole mechanism runs successfully and evenly. The mechanism of the design was simulated in Solidworks software.

Screenshot 2015-06-27 10.13.01副本 Fig12. Axonometric drawing of the core rotating part on the right side. One arm animation picture on the left side.

Screenshot 2015-06-27 10.53.06副本 Fig13. The joints detailed analysis.

An section animation of the core rotating part shown:

With the design of one single arm, the four multiple rotational axis arm was designed, as shown in Figure 13.

four arms render pic

Fig14. Four multiple rotational axis arm analysis.

Screenshot 2015-07-18 17.11.59副本

Fig15. The latest arm version with laser set.

Finally, the overall installation is tested in the observatory, using a holding structure which stands on the dome part to firmly hold it (Figure 14).

Final test in observatory

Fig15. The final installation onsite.


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