Building a Frame

I had originally planned to use trussing to support the lights and had planned to use this to secure the PIR detectors in position and also to cable tie the wiring to. Although this would probably have been the easiest option considering it is the standard for stage lights, such as the follow spots that I plan to use. I was considering methods of how I would be able to hide or cover the trussing so that all it is not completely visible, and consequently will make it appear that the lights are coming out a blank space. I don’t want the technologies and equipment behind the project to be visible, as I feel that it will cause distraction from the light and the relationship between the user and the light. Although, as mentioned earlier, interaction cannot not be entirely sub-conscious I would like to remove the idea of ‘communication with a machine’ as much as possible. As a result I have decided to construct a platform the can be suspended that will house most of the equipment involved with the project. This will include, the lights, the PIR detectors, the wiring, the DMX controller, the PIR controller and the laptop that will control all of the processes. Although this may sound like a lot of equipment to secure, it is relatively lightweight, and should not pose a problem in terms of weight.

The structure will be similar to the flats that are used in the university studios, but will be slightly smaller and more lightweights. The structure will be built out 37mm by 63mm (approximately 1.5 inches by 2.5inches) CLS construction timber, which is extremely sturdy, and supportive. The beams will be 2400mm in length (which is approximately 7"10) and will form a square. Four extra beams that will be secured across the width will then support the square. Over this beamed structure I will secure 6mm plywood boards, acting as a skin upon which the equipment can be secured. Holes will then be cut into this skin, which will allow the lights, which are secured above, to emit the beam. In order for this to be safe as possible batons will be used to securely hold the lights in place. The entire structure will then be supported from the ceiling via welded steel chains that will be connected to the structure with 30mm steel hooks. The structure will be made in a way that will enable it to disassemble easily and then be reassembled once in the studio. This will be made easy by cross dowelling bolts. All of the equipment that is necessary for this to be built is available at Homebase or B&Q. I will then paint the underside of the structure in matt black paint so that it is more camouflaged with the darkness of the structure. Fortunately for me my stepfather is a budding carpenter and offered to help with the construction of the structure. This was beneficial, as although the build would not have been too complicated to produce it would mean that it would be as safe as possible. Health and safety is a big consideration for a structure such as this, something that will be considered later in this text.

Pricing:

Here is a breakdown of the pricing of the materials needed for the structure:

CLS construction timber beams: £1.79 each £1.79 x 8 = £14.32 (homebase)
Welded steel chains: 10m x 8mm = £14.49 each (screwfix)
6mm Plywood Sheets: 2440 x 1220 = £14.86 x 2 = £29. 72 (homebase)
Cross dowelling bolts: £1.90 per pack of 50 (screwfix)
Cross dowels: £1.99 per pack of 50 (screwfix)
Steel Hooks: £2.29 per pack of 5 (used 8) £2.29 x 2 = £4.58 (screwfix)
Black fabric: £18.00 (Matalan)

TOTAL: £85.00

Construction:

1) As the wood already came in lengths of 2400m this dictated the size of structure. In order to produce a square Cut the two side lengths slightly shorted enabling the pieces to be bolted together.

2) Cut recesses (grooves) in left and right lengths, which the cross middle support could then be supported in.





3) Repeated this process with the other two supports.



4) Bolted in position with cross dowels, allowing for easy disassemble.

5) Attached plywood skin to the structure using screws



6) Added small feet to the underside of the structure to allow the platform to be raised slightly of the ground, which prevented the PIR detectors from being damaged.

Health and Safety:

As you can probably imagine there are large health and safety risks associated with a structure such as this, especially considering that it will be hanging from a ceiling and users will walk underneath it. In order to properly assess this I contacted Robert Belton who is the studio manager and organised a meeting between, him, John Viney (the set technician) and myself.

The weight of the structure is the main determining factor of safety and how the structure can be supported from the ceiling. In order to consider this I need to consider the total weight of what would need to be supported. Firstly each light is 10kg (30kg for all lights), the PIR detectors are 80g each (400g for all PIR detectors), the laptop that will be used is approximately 3kg, the structure is wooden structure is 40kg, and I would allow for additional 5kg to cover the weight of both controllers, the wiring, batons to hold the lights in place, power cables, extension leads and everything else that would be housed on top of the structure. The total of all of this comes to 78.4kg, which I will round up to 80kg, to be extra safe.

This is a generous calculation, as I think that it is better to be over the actual weight than under, as any calculations considering the supports will then certainly be safe.

Introduce Sound?

Although I haven’t given the use of sound much consideration during the planning and production of the project, it is something that I would like to consider. I have worked with sound in sensory projects before this and it has always proven to be a valuable asset to the piece. Sound works extremely well in interactive pieces as it gives the user a clear indication that an action/input has been registered. For example, when a user of a computer uses a mouse, a press is acknowledged with a click noise. This is a sound that could be avoided, but is employed as it adds certainty to an action. If the click did not sound then the user could be left wondering if they had clicked adequately.

I am confident that the changes in light, whether colour or on/off, will highlight a change adequately. I like the idea of introducing sound, not only as a method of highlighting change, but also as it helps to engage more senses, making the piece more engrossing.

It is important however that the sound does not distract from the main ideas of the piece, which I still want to be fully focused on the light and how it reacts to touch. The introduction of sound will add a recognition system and another aspect to the relationship between the user and the installation.

As I have already mentioned I do not want the sound to detract from the lights. This means that the sound should be kept to a minimum, maybe introducing a single noise when movement is detected. This could be something as a simple as a click, a tap or knocking. It is a decision that I cannot jump into as although it won’t act as the main output of the installation it will still be extremely noticeable, and if it is the wrong sound it will change the entire dynamic of the piece.

I have also highlighted in earlier entries the interactive aspect of the project is extremely integral to the work, and this is something that could be depicted with the choice of sound. One of predominant ideas that has featured in all of my work since working with new media has been to investigate different methods of computer control, rather than simple using a mouse and a keyboard. As I have mentioned a mouse click is an important method of recognition for a user, as it highlights that a command has been registered. I think it would be quite effective to use this sound within the installation. The sound will play every time that motion is detected.

Minimaforms: Memory Cloud

Memory Cloud was an transient light environment that was exhibited in London's Trafalgar Square in October 2008 that I was fortunate enough to see. Memory Cloud was based on smoke signals, which is one of the oldest forms of visual communication. The public were invited to participate in the installation by sending text messages that were then converted into plumes of smoke. In reality the text messages were projected through clouds of smoke, but gave the illusion that the messages were in fact in cloud form.



The light acted as a virtual ink scrawling through the smoke that perceptually wrote and then erased. This work was extremely relevant to my project, as the main features revolved around smoke and light. It was fascinating how vibrant the text looked as it was projected across the square. Although some texts were not as visible as others, especially when the wind picked up and blew the necessary smoke away from the light, it helped to enrich the idea of smoke signals. As my project is planned to be shown in an enclosed area, wind should not pose a problem, however it is something to consider, obviously not external wind, but any breezes or movement that could effect the movement of the smoke. If the smoke is seen to be moving around the space it could ruin the solidity of the columns.

The above picture was taken from the Minimaforms website as I felt that it help to support my own photos from the installation.

Soldering/DMX controller

Although the USB controlled DMX controller was going to make the project easier to finish (enabling the use of DMX to be controlled by Visual Basic) it did pose another problem. The kit that I has purchased from Maplin was not assembled, and required relatively expert soldering for a total of 119 solder points (shown in the picture below, every gold circle corresponds to a solder point). Although I had some experience with soldering it had been several years since I had last used one, I think the last time would have been during sixth form college.

I first had to buy a soldering kit, which I luckily found cheaply in a home furnishings shop, for only £7.99. The kit came with everything necessary to complete the solderin; a soldering iron, a solder extractor, a spare head to the iron, a holder for the iron and solder.

This was a challenge that I was not particularly looking forward to as the board was imperative to the project and had been relatively expensive therefore it was not something that I wanted to get wrong. I decided that it would be wise to do several test and retune my soldering technique by testing on a spare piece of board and some wire.







Although the solder points probably aren't up to an expert's level I was confident that they would be adequate, which was pleasing as it meant that I would not have to pay somebody to do it for me.

The instructions for the procedure were extremely thorough and easy to follow. Upon starting I was pleasantly surprised with the joints, which were neat, and well placed, shown below. I tested the joints with a digital multimeter as a continuity tester, which confirmed that the joints were satisfactory to support a current.





With my confidence levels increased by these initial joints I proceeded with slightly less caution, but it was a long process.

After I had finished soldering the initial components, including the diodes and resistors I was pleased with the progress, and confident that the finished product would be suitable and would work sufficiently.

Although the initial joints had worked extremely well, it became more difficult once I had to operate closely to other joints, as I had to make sure that the solder did not touch the solder of another component, which would prevent the board from operating properly. As a result I had to use a solder extractor, to remove the touching solder from the joint, which meant that the whole process would take even longer.



This became especially relevant once I started to connect the IC sockets, which have several pins, some of which are not suppose to touch and some are. This meant that I needed to carefully following the schematic diagram in the instruction booklet.

Following approximately an hour and a half of concentration the board was finished and was able to be secured into the case that is provided with it.







At this point there was a real sense of achievement, but I was dubious about whether it would work or not. Much to my amazement it did work first time, and I was soon able to control a light through the the software that was provided, simply with the click of a mouse. This was an exciting breakthrough with the project.

USB DMX controller interface

Although DMX can be controlled using a DMX controller, I need the system to be able to be pre-programmed using Visual Basic, and consequently need a method of connecting the DMX lights to a PC. I was informed by the lighting company that I hired the lights from that such converters do exist. Following a quick search I discovered that Maplin stock a controller, but it does not come assembled. However, I was certain that this component would be vital to the installation, as I would not be able to control the lights without it.



Specifications:
- connected and powered through USB
- 512 DMX channels with 256 levels each
- 3 pin XLR-DMX output connector
- optional 9V battery needed for stand alone test mode
- solid state - fuse protection on DMX output
- dimensions: 106 x 101 x 44.5mm / 4.2 x 4 x 1.75"

http://www.velleman.be/downloads/0/illustrated/illustrated_assembly_manual_k8062_rev3.pdf

The DMX controller converts the signals and commands that the PC sends through USB into a format that the lights can understand. Without the controller the lights would not be able to understand the signals that are sent from the computer. As mentioned the the unit comes with test software, as well as a DLL (Dynamic Link Library) library of code that can be loaded and linked into the executing program, which means that the DMX controller can be called upon without having to program it yourself.

This unit had everything that I would need in order to make it work within the installation, the only problem that it would pose was concerning the soldering aspect, something that I have not done for years. I was confident however, that following some practice I would be able to sufficiently solder in order to connect everything to the circuit board. As well as practicing my soldering techniques I need to get on with the software side of the project, which is now the main focus for the remainder of the time.

Atmosphere of the Installation

It is useful to consider the atmosphere of the installation, and how I want the installation to 'feel' during the presentation. The installation will be presented in studio 1 at university, which is a large space. This will affect how the project is perceived and how the users see the light. The space will also be relatively quiet which will also effect the presentation.

As the users enter the space they will be greeted by the structure with one column of light dissecting the darkness of the rest of the room. I hope that this will be quite enchanting and appealing, and the users will then be invited (one at a time) to move towards the light and explore the space. The light will appear quite mysterious, especially as the rest of the room will appear misty due to the use of haze. I hope that the quietness will add to the exploratory sense of the work, as the user will feel quite alone in the darkness, with only the columns of light to explore. I have been involved in other sensory projects and have found that such works offer the user a more rewarding experience when they are on their own, as they generally feel freer to explore. I think that the piece will appear quite magical and connote ideas of science fiction. The light will hopefully appear crisp, which will be visually stunning. I want the users to want to explore the light, to move towards the columns at investigate them further.

DMX Controlled Lights/ Chauvet Followspot 400g

As mentioned in the previous post I have discovered a follow spot that can be controlled by DMX, the Chauvet Followspot 400g. The Followspot 400G is a 2-channel DMX spotlight featuring 7 dichroic colors, a variable electronic dimmer, variable mechanical iris, variable mechanical focus and has a single gobo slot. The light is also smaller than other follow spots that I have seen and does not get as hot, which will mean it is easier to handle during testing, set-up and the actual presentation than if I was using a full sized follow spot.





The specifications are as follows:

2-channel DMX-512 followspot
7 dichroic colors + white: (red, blue, green, yellow, orange, magenta, UV purple)
Variable electronic dimmer (0-100%)
Variable mechanical iris
Variable mechanical focus
Single gobo slot with 4 free gobos
Beam angle: 2 ° - 12°
Lux: 48,420 @ 1m
Light Source: ENX 82V 360W 75hrs
Power and current: 120V, 60Hz:326W, 3A operating, 8.2A inrush, PF0.92
AC power: 115V/60Hz or 230V/50/Hz
Weight: 20.6 lbs (9.34kgs)
Size: 22.5in x 11.5in x 6.38in
572mm x 292mm x 162mmm

User Manual: http://www.chauvetlighting.com/products/manuals/tfx-fs360_ug-159.pdf

As you can see the beam angle can be as little as 2 degrees, which is the narrowest that I have seen whilst I have been considering stage lights. This will mean that the beam will be almost perfectly collimated, which will hopefully avoid the light from looking like a spotlight and more like a architectural column. Although the light is not completely controllable through DMX, the two options that are available are colour and dimness, which can effectively control if the light is on or off. These are the two options that I wanted to be able to control for the installation.

There are, however, some disadvantages to the 400g. As it is a smaller light it is not as powerful as standard followspots, so the light that it produces will not be as bright as a larger model. This will effect the columns, as the contrast between the light and the darkness will not be as vast, meaning that the columns may not appear as shape and distinctive as they possibly could have been. The beam of light that is produced is also not as sharp as it could be, which will also mean that the columns aren't as distinctive as they could have been if a different light was used. Another disadvantage of the lights is the bulb life. Each bulb lasts for only 120 hours, and the company that I hired from suggested changing the bulb after every 100 hours in order to keep a sharp beam. Although this will not present a problem for the presentation, which will only last for a couple of hours, it may pose a problem when exhibiting the installation in the final year show.

Although the lights do have disadvantages, the advantages greatly out-weigh these, providing a narrow beam with the flexibility that I was looking for.

Change in Lights: Goodbye Motors

I have recently been in Cheltenham, as I find it easier to work there. However, I was aware that I would need to do some further testing, and begin to make final decision, adjustments and amendments concerning the lights. As the lights that I was planning to use are located in London, I decided to try and locate some in the local area. Whilst discussing this with a firm called 'New Day' I was informed that they had a DMX controlled follow spot in stock. This was something that I had not heard of before; I was under the impression that all follow spots were manually operated. Although I have been planning to use motors to move filters across the face of a follow spot, it sounded like a DMX controlled system would be easier to use, program and would greatly reduce construction time, as it would mean that I would not have to spend hours aligning and positioning motors. Although I was not certain that DMX could be controlled in Visual Basic, the programming language that I am using throughout this project, I decided that these lights would be worth a closer inspection. I was informed that the lights were Chauvet Followspot 400g.

Once I had actually seen the lights, tested them, and talked the ideas through with the staff at New Day I was confident that this would be a better option for the installation than the manually operated follow spot that I had planned to use before hand.

Structure of the presentation

I had originally planned to construct a box like structure out of the studio flats. The flats would create an enclosure that would prevent the user from seeing the winches that support the trussing and the lights. This enclosure would also act as a means to contain the haze that would otherwise disperse. In order for this to be suitable for the presentation, the enclosure would have to be quite large, as I want the users to be able to walk around the lights freely, with at least a 1-meter radius, and at this stage I plan to have the lights approximately 1.5 meters apart from one another. Although I did like the idea of producing a solid structure I still want the presentation to be quite free, i.e. I don’t want the user’s movements to be restricted.

As a result I have decided to use a different sort of structure, one that can be suspended from the ceiling. The structure will be hung approximately 8 feet from the ground, and will house all of the equipment (apart from the haze machine) that will be used within the presentation. As a result this will not be able to be seen by the users, rendering it more ambiguous than if it was all supported by a trussing structure. As well as the PIR detectors, controllers, and wiring the structure will also support the lights, and will have sufficient holes in place to allow the lights to shine through, which will give the appearance that the lights are coming from the wooden structure, almost like they are dissecting it. I will also paint the structure black so that does not stand out from the rest of the room, hopefully allowing it to be slightly camouflaged.

As the structure will be supported from the ceiling it will mean that there is more freedom for users to move around the structure. It does mean however that there will not be a wall to prevent the haze from dispersing. Although, this may present a problem following further testing I am confidant that if the haze machine is placed in the correct position then it will provide a large enough quantity of haze to allow the beams to be fully seen. The studio also has large curtains in it, so if the structure can be placed relatively near these, they will act as a make shift wall, stopping some of the haze from escaping into the rest of the room.

The studio that I plan to show the presentation in is a large room, and as a result I would like to use one of the larger studio flats to split the room into two, which will prevent the users from being able to see the structure as they enter the room. At first I would like the users to explore the piece one at a time, and then once each user has explored I think it would be interesting to watch others explore the piece from a distance.

There are health and safety implications attached to this idea of hanging the structure that will have to be considered and discussed with the studio manager and technicians.

Structure of Lights

As I mentioned several times during my consideration of architecture the structure of the lights is extremely important to the installation. I want to make sure that I utilize the space of the structure that the lights will be contained within in, as well as considering how the structure will appear. When columns are used in architecture they are normally equally spaced apart from one another, something that will be apparent with the placement of my columns.

With this is mind I consider several different options. In order to do this I decided how big the the installation space would be, (8ft by 8ft), and drew a square regarding how this would appear. I divided it into equal sections, as this enabled me to better place the lights in terms of distance from one another. I eventually decided upon a final six option (seen below):



Whilst considering the the floor plan I imagined that the user would enter from the left hand side, making the right side the back of the installation. I wanted the user to walk into the structure and to the back of the installation, as I don't think it would be right to walk in and straight away be greeted by a column. This will allow the user to become fully submerged within the installation. Once this light has turned off I would like the next column to be relatively close to the first, with a simple turn taking the user to its side. finally I would like the third column to be positioned as far as possible from this light, (near the entrance side of the installation) requiring more movement from the user. I think such a route will provide the optimum use of space and allow the user to fully explore. I think that these placements will also provide an increased level of surprise as the user will have their back to each of the columns that turn on. I have therefore decided upon the positions outlined in the first diagram, as they fit perfectly into the needs that I have just specified.

Controlling the Servos

Servo motors rely on electronic pulses to control them. The pulses that they receive are extremely rapid, one is expected every 20 milliseconds, and are measured in length to determine how far the motor works. For example, if a pulse of 1.5 milliseconds is received the motor will turn 180 degrees. I am uncertain, however, that the I will be able to generate pulses this quickly using the system that I plan to use. For this reason I have been researching into servo controller. Unfortunately I was unable to find any in any shops, so had to resort to online for one. There were several options, but most of which had to be shipped internationally, either from Europe or America. As I was slightly pressed for time, I continued to try and find a suitable one located within the UK. Eventually I settled on one from Technobots.co.uk. The Pololu Serial 16-Servo Controller allows you to control up to sixteen RC servos from almost any robot controller or computer.



The interface to the servo controller is a standard RS-232 serial port, which meant that it would be possible to control it using the PC that I had planned to use in the installation. Multiple servo controllers can be connected to a single serial line, and they are compatible with servo controllers, meaning that almost an arbitrary number of servos and motors can be controlled with one serial line.

The unit cost £51.14 including the VAT and shipping, which although was relatively expensive was necessary to make the project work successfully. Upon arrival I was considered about the unit, as it was extremely small, and was not pre-assembled, meaning that there would be lots of precise soldering connections, something that I did not like the idea of.



http://www.technobots.co.uk/Data%20Sheets/3800-103.pdf

How would the Servos Work?

The follow spot that I plan use, like most follow spots, has a colour magazine attached to the front of the light. This magazine allows colour filters to be moved in front of the light, consequently changing the colour.

Unfortunately this system is a manual system and cannot be controlled by a computer. As a result I have decided to construct a method of controlling the motors using servo motors. I have already highlighted how a servo motor works; pulse coded modulation controls how far the motor will move. In order to harness this ability I will have to send a pulse to the servo every 20 milliseconds. I am uncertain however that the computer that I am using will be able to generate pulses that quickly. This is something that will have to be tested. If the computer is able to generate pulses this rapidly I will be able to control the length of the pulse that is sent to the servo thus controlling how it moves. If this can be controlled, I will then be able to attach a metal arm, which can be attached to the colour filters. As I have tried to highlight on the picture below the colour filters rotate around a central point, moving into place in an arcing motion (represented by the arrow).



I will then be able to attach an arm to the motor that will move the colour filter into place and back again. In order for such a system to work each arm would have to a motor attached to it. Although I will need to make a final decision about the colour scheme I am currently thinking that I will use red, green and blue. If I stick to this plan I will have to have four motors for every light, which will amount to twelve. There will be four motors per light as I also plan to utilize the metal sheet at the front of the magazine, which will make the little appear to turn on or off. This may prove to be a problem, as the experimental interface board that I am using to detect the signals from the PIR detectors only has 8 digital outputs, so I would need to purchase another one in order for this plan to work. As you can see there are several potential problems with this idea that will have to be tested. I will also have to test how the arms can be attached to the motor, and if I can gain the necessary movement from them. If this system cannot be implemented properly I will have to find another solution to control the colour filters.

Motor from CD-ROM

A CD-ROM drive, from a standard PC, has a stepper motor secured in it that pushes the draw backwards and forwards at the push of a button. As I had an old CD-ROM that wasn't being used I decided to try and take it apart to see how it worked, if it could be reused for my project.

I started by removing the casing around the CD-ROM, which simply involved unscrewing some small screws. Once inside the drive, it was clear that although the motor was visible from the side that it could not be easily accessed. In order to get closer to the motor, the tray and some of the circuitry had to be removed, which although it was a risk that it would break the drive, was still necessary. As predicted one of the circuit boards broke, but this did allow access to the motor. It was interesting to see how small the motor was (pictured below), but then it only has to provide a small amount of torque to be able to power the movement of the tray.







Although, I don't think that the motor will be able to be used in the project it was interesting to see how it works, in terms of the cogs that are attached and it was a visual way of understanding the operation of the motor, i.e. the chain of operation.

Motors: Stepper Vs Servo

Stepper motors:

A stepper motor's shaft has permanent magnets attached to it. Around the body of the motor is a series of coils that create a magnetic field that interacts with the permanent magnets. When the coils are turned on and off the magnetic field causes the rotor to move and it is this sequence of on and off that determines whether the motor rotates forwards in reverse. This sequence is known as the phase pattern and there are several types of patterns that will cause the motor to turn. Common types are full-double phase, full-single phase, and half step.

In order for a stepper motor to rotate, the coils must be constantly turned on and off. If only one coil is energized the motor will just jump to that position and stay there resisting change. This energized coil can pull the full current, without moving. This ability to stay rigidly in position is often considered to be one of the main advantages of stepper motors. The torque at standstill is called the holding torque. As stepper motors can be controlled by turning coils on and off they are easy to control with digital circuitry and microcontroller chips. The controller simply energizes the coils in a certain pattern and the motor will move accordingly. At any given time the computer will detect the position of the motor, as it is easy to track the number of steps that are moved. Most stepper motor control systems will have a home switch associated with each motor that will allow the software to determine the starting or reference "home" position.

Servo motors:


Although there are several different types of servo motors a normal DC motor has one coil with 2 wires. If a charge is connected to the wires the motor will spin, unlike a stepper, which will move a step, and then stay stationary until the coil is turned on and off again.

Servo motors have control circuits, and a potentiometer (a variable resistor, aka pot) that is connected to the output shaft, which allows the control circuitry to monitor the current angle of the servo motor. If the shaft is at the correct angle, then the motor will shut off. If the circuit finds that the angle is not correct, it will turn the motor the correct direction until the angle is correct. A normal servo is used to control an angular motion of between 0 and 180 degrees; the mechanical stop, built on the output gear, will prevent it from turning any further.

The amount of power applied to the motor is proportional to the distance it needs to travel. So, if the shaft needs to turn a large distance, the motor will run at full speed. If it needs to turn only a small amount, the motor will run at a slower speed, a process that is known as proportional control.

RC Servos:

The type of servo motor that I will be considering for this project is the type that is commonly found in hobby airplanes and cars, known as RC (remote controlled) servo motors. Although such motors are housed in small boxes, they contain a complete servo system, including; a motor, a gearbox, feedback device (pot), servo control circuitry, and a drive circuit.

Unlike DC motors, RC servos normally have 3 wires: +v, ground, control. The control wire is used to communicate the angle, which is determined by the duration of a pulse that is applied to the control wire. This is called Pulse Coded Modulation. The servo expects to receive a pulse every 20 milliseconds (.02 seconds) and it is the length of the pulse that will determine how far the motor turns. For example, a 1.5 millisecond pulse will make the motor turn to the 90 degree position (often called the neutral position). If the pulse is shorter than 1.5 ms, then the motor will turn the shaft to closer to 0 degrees and if the pulse is longer than 1.5ms, the shaft will turn closer to 180 degrees.

Colour and on/off

As the project has progressed the initial ideas have developed and consequently I am now trying to something that is quite different from the original plan. As previously outlined it became unlikely that I would find a method of producing a square beam of light, and also to make it bend or contract. Since then I have discovered follow spots, which can produce a relatively collimated beam over the distance that I intend to throw it over. On the follow spot that I tested there was a magazine fitted to the front that contained 5 different colour filters, and a metal disk that could be moved into place that would give the impression that the light had been turned off.



This led me to the idea of having three separate light columns that would be able to change colour and turn on or off (similarly to Siegrun Appelt) as users moved around them. In order for this to be achievable the sensors would have to be connected via a computer to a system that could move the filters back and forth in front of the lights. Such a system would allow for three columns of light to change colour and to appear (turn on) or disappear (turn off). Although this is quite different from the original plan I feel confidant that this would be an effective piece of work.

What Colour?

As there are three columns of light I wanted to keep the colour scheme to three colours as well. The most common colour model is RGB (red, green and blue). Red, green, and blue are the primary stimuli for human color perception and are the primary additive colors. The relationship between the colors can be seen in this illustration below:



The secondary colors of RGB, cyan, magenta, and yellow, are formed by the mixture of two of the primaries and the exclusion of the third. Red and green combine to make yellow, green and blue make cyan, blue and red make magenta.
The combination of red, green, and blue in full intensity makes white. White light is created when all colors of the EM spectrum converge in full intensity. This is something that I can consider with the order of colour changes within the installation.

RGB as a color model relates very closely to the way that we perceive color with the r g b receptors in our retinas. RGB is the basic color model used in television or any other medium that projects the color. It is the basic color model on computers and is used for Web graphics, but it cannot be used for print production.

Due to the importance of RGB, and the fact that in full intensity they make white light, the other form of light present in the installation, I think that it is highly appropriate to use the colour scheme in the installation.