Creation of an Auto-Tracking Theatrical Spotlight · 2008-12-24 · Creation of an Auto-Tracking Theatrical Spotlight First Semester Report ... Figure 3 Version 1.1 Chapter I: Introduction

1 Updated : 12/16/2008 Version 1.1

Creation of an Auto-Tracking Theatrical Spotlight

First Semester Report

Fall Semester 2008

By

Eminet Ayele

James Hagan

Andrew Katers

Nicholas Powers

Prepared to partially fulfill the requirements for ECE401

Report Approved: ___________________________________________________ Project Advisor

___________________________________________________ Senior Design Coordinator


Abstract

What are the two big factors that can influence the effectiveness of a production on the

stage, or a presentation? Time and money. There are people behind the stage and the curtain

directing and assisting the actors, controlling the lights, and cueing the show. What is the

common element between all of these things? The potential for human error. In order to

increase the effectiveness of a production or presentation the potential for human error can be

eliminated from certain systems. One of the systems that can be changed is manual control of

spotlights. Our project is going to be the development of a device that will be able to

supplement the manual control of spotlights with the potential for automated tracking of an

actor/ presenter on stage.

Recent technological developments in the wireless field have allowed us to develop a

project that differs from existing implementations. We will be utilizing a specific set of

hardware from Texas Instruments combined with a motorized theatrical light from Electronic

Theatre Controls. This specific set of hardware is unique in the capabilities it affords us when

developing a wireless tracking solution. The hardware from TI has a specific built-in feature

know as “Z- Locator” which allows the team to determine the X-Y location of the presenter. The

X-Y data will then be used to properly position the light so that it targets a desired position.

Throughout the semester we have been experimenting with this system to determine

how viable it would be for this application. We have tested the radio functions of the

processors in a theatrical environment which is similar to real life situations regarding

interfering noise. It was determined that the hardware we are using is sufficient enough for the

environment and accuracy which we require for proper functionality. The next steps for the

project will be to continue programming the processors and create circuit boards for all of the

needed components.


Index

Title 1

Abstract 2

Index 3

List of Figures 4

I. Introduction 5

a. Previous Work 5

b. Current Work 6

II. Components 7

a. TI Hardware 7

b. ETC Hardware 7

III. System Breakdown 8

a. Control Module 8

b. DMX Processor 9

c. DMX-512 11

d. Triangulation Processor 12

IV. Hardware 15

V. Timeline 16

VI. Conclusion 17

Appendix A – Abbreviations 18

Appendix A – Budget 19

Appendix B – UCA Signal Analysis 20


List of Figures

FIGURE 1 FOGBox 5

FIGURE 2 SLIDEBox 5

FIGURE 3 WALLBox 5

FIGURE 4 Wireless Box 5

FIGURE 5 CC2430 6

FIGURE 6 CC2431 6

FIGURE 7 Grid Layout 6

FIGURE 8 ETC Source Four Revolution 7

FIGURE 9 System Breakdown 8

FIGURE 10 Main Program Flowchart 9

FIGURE 11 Subprogram Flowchart 10

FIGURE 12 DMX Capture 11

FIGURE 13 Triangulation Flowchart 13

FIGURE 14 Calibration Mode Flowchart 15

FIGURE 15 Timeline 16


Chapter I: Introduction to the RAMBox:

a. Summary of previous work

The first RAMBox project was started in 2003. At the time there were no devices that could control a PowerPoint slide show through the DMX-512 Protocol. Seeing a need for this the team decided to create a device that could accomplish this goal. The team created a device that would receive a signal through the DMX Protocol and transmit the given command to a waiting computer program which would interpret the signal and use it to control the computer functions. The device was quiet successful and the resulting design was purchased by ROSCO Industries. ROSCO then developed the design into a commercial product which they sold as “Keystroke.”

During the following years the project continued to thrive and resulted in several other functional DMX devices. “FOGBox” (Figure 1) was used to control a fog machine onstage through the DMX network, “SLIDEBox”( Figure 2) was used to advance a slide projector, and “WALLBox” ( Figure 3) was a DMX controlled power strip. More recently the project has moved into the wireless realm with “WIRELESSBox” (Figure 4) which allowed the transmission of DMX signal without expensive cabling. Last year’s project was the development of a wireless controller for LED panels & a stage prop candle.

Figure 1 Figure 2

Figure 3 Figure 4


b. Current Work

At the beginning of this semester, the RAMBox team made a decision to design an auto tracking theatrical stage light. This careful decision was based on the history of RAMBOX to make theatrical devices more capable and resourceful using the DMX-512 protocol. In addition to that the team recognized the broad capabilities of the TI development kits that were already a part of the RAMBox project from the previous year. This design can be applied to a wide variety of situations such as public speaking forums, professional presentations, and theatrical stage performances.

The brief plan of this year’s project is to auto track a presenter or an actor in a stage with a theatrical stage light by having him/her wear a transmitter. This is accomplished by using the two CC2430 and CC2431 TI development kits that were donated to last year’s RAMBox project.

One CC2430 will be working as blind node, while we have many of the reference nodes. (Figure 7). The blue dot represents the actor while the reference nodes are placed at specific locations on the stage (red dots). Reference nodes are a stationary devices with a well-known and stable location (X/Y position), that can tell the Blind node where its location is on request. We need between 3 and 16 reference nodes to calculate the location of a blind node (the more nodes we use, the greater the accuracy). Then blind node, when requested, will calculate its location based off the data it received and sends that information to the controller.

Figure 5 Figure 6

Stage

= Reference

Node

= Blind Node

Figure 7


Chapter II: Components

a. TI Hardware

Texas Instruments has provided multiple development kits to the project that are being carried

over from the previous year’s project. These consist of a 2430/2431DK development board that is used

to run diagnostics and program the actual 2430/2431DVM modules (Figures 5 and 6). The reason these

were chosen for this specific project is due to some unique features they posses. Both chips are based

off of the Intel 8051 processor. The 2431DVM also contains extra logic for the TI Z-Locator software

stack. All of this hardware was inherited with the project and thus required no spending as of yet.

The 8051 processor is a 16 bit processor containing 16kb of program memory and 128 bytes of

data memory. It runs at a clock speed of 32MHz. This processor is overkill for this project but has

provided us with a unique opportunity with its extensive feature list. It is programmable in C which helps

to minimize the learning curve and there exists a significant amount of demo code to ease the learning

process.

The main point to these chips sits with the Z-Locator hardware of the 2431DVM. This allows the

processor to determine its location on an X-Y grid relative to a set of known reference nodes consisting

of 2430DVM’s.(Figure 7) This is key to our project since it allows us to pinpoint the actor’s position on

stage and translate that into angles that the light will be adjusted to. These processors are also low

power and compact making them ideal for carried modules.

b. ETC Hardware

Electronic Theatre Controls has provided the project with a

Source Four Revolution Light (Figure 8). This is the other key to our

project which will help to minimize the amount of necessary

engineering. The light is a 2-axis motorized theatrical light that is

completely compatible with the DMX-512 protocol. It uses

approximately 19 channels to control various functions of the light.

The acquisition of this light meant that we do not need to engineer

our own mount and motor system for a traditional theatre light.

This is significant since motor controls can be notoriously difficult

and being stuck on this problem would have slowed us down quite

a bit. Figure 8


Chapter III: System Breakdown

When the system is broken down it falls into 3 major parts; The Grid/Blind node system, the

Control Module, and the light. The Grid consists of 2430DVM Reference Node chips with known X-Y

coordinates and the Blind Node which determines its location from the Reference Nodes.

The Control Module consists of 2 processors; The DMX Processor and the Triangulation

Processor. The DMX Processor will handle all DMX interactions such as determining the inputs from the

light board and outputting the lights DMX code which contains the necessary angles to center on the

blind node on stage. The Triangulation Processor handles the data flowing from the blind node and

determines the appropriate angles for the light to point at relative to its location from the blind node.

The light is the final part of the system. Its actual function is limited to receiving the completed

DMX signal and then orienting itself in the appropriate direction so that is will center on the blind node.

a. Control Module

The control module consists of two Texas Instrument CC2430 processors. These

processors are responsible for triangulation calculations and DMX 512 bit stream encoding and

decoding. The purpose for two different processors is to ensure a fast response of the light to

changes in location of the presenter. Since the controller module is reading a continuous bit

stream from the DMX slider board, processing time is of a major concern. By splitting the tasks

Stage

= Reference

Node

= Blind Node

Triangulation

Processor

Light Board

DMX

Processor

Other DMX Equipment

Control Module

Figure 9


of this module between two processors, we will be able to dedicate a portion of the processing

to reading and outputting this stream.

b. DMX Processor

The DMX processor is the process by which the light board or the control module will

connect to and communicate with the Source 4 light. The main DMX process will initialize all of

its registers, gather the triangulation information needed from the Triangulation process, and

then read in the correct light board channel to determine which mode the control module is

currently in. The channel slider on the light board can move from a bit value of zero to 255.

There are currently three modes that the light can enter: Active mode, Bypass mode, and

Calibration mode. If the value on the slider is between zero and 64, we are in Active mode. If

the value on the slider is between 65 and 250, we are in Bypass mode. And if the value on the

slider is greater than 250, we are in Calibration mode. The flowcharts for the main DMX

process and the three separate modes are shown in figures 10 and 11.

Figure 11 Main Program for

DMX Processor

Initialize

Registers and

Memory

Read In

Desired

DMX

Channels

Which Mode?

Check Value of

“Mode” Channel

Active

Mode

(value less

than 64)

Bypass Mode

(value

between 65

and 254)

Calibration

Mode

(value =

255)

Get DMX Start

Address from

Triangulation

Processor

MAIN PROGRAM Figure 10


In Active mode the light will be following the actor or presenter where ever they move to on

stage. The light will enter Active mode after running a check on the correct channel to

determine if it is within the correct value. Once in Active mode the light will track the actor by

first gathering the correct angles from the Triangulation process. The Triangulation process

then will turn the angles into a DMX value and send them over to the DMX process so they can

be inserted into the DMX bit stream. Once the DMX process has the triangulation values, it will

store them into a register and insert them into the DMX serial bit stream that travels to the

light using a UART Chip (Universal Asynchronous Receiver/Transmitter). This will happen

multiple times a second. After each execution the Control module will again check what the

slider value is at.

Active Mode for

DMX Processor

Get Current Light

angles from

Triangulation

Processor

Send DMX

String to the

Light

End Active

Mode

Insert Angles into

Outgoing DMX

Data

ACTIVE MODE

CALIBRATION

MODE

Calibration Mode for

DMX Processor

Set Program Flag

High for

Triangulation

Processor

Send DMX

String to the

Light

Request for

Rotation Value 2?

End Calibration

Mode

No

Yes

Give Rotation

Value 1 to

Triangulation

Processor

Give Rotation

Value 2 to

Triangulation

Processor

Bypass Mode For

DMX Processor

Send DMX

String to the

Light

End Bypass

Mode

BYPASS MODE

Figure 11


Bypass mode will mostly be hardware. The main DMX process will check that the

module is in Bypass mode and it will feed the DMX values from the light board directly through

to the light. This mode is used mostly for a stationary spot light or if the light board operator

wants a desired position for the light other than the actor or presenter on stage.

Calibration mode is how the light will be programmed to the stage, so that it will know

when an actor moves from point A to point B, how far it needs to sweep the stage. This mode

will be the most complex of the three. This mode is primarily run by the Triangulation process

instead of the DMX process. How it works is the actor will move to one point on the stage. The

user at the light board will then center the light on the actor how they want it to appear. Once

the light is set the actor will press a button on their blind node to signal to the control module

that the spot is set. The DMX processor will then take the current DMX values for the light and

relay them over to the triangulation processor. The Triangulation processor will then use this

value to calculate the correct triangulation angles to the light. This process will then be

completed three additional times to accurately calibrate the light to the stage.

c. DMX 512

DMX 512 is a protocol by which all light boards communicate with lighting equipment. It

was originally designed to only communicate with the lighting equipment but it is also used to

operate anything that can be controlled digitally. Some of the problems with DMX 512 is it is

unidirectional, serial, and asynchronous. The unidirectionality to the signal means that there is

no error checking with the DMX signal. So it should not be used for any complex systems that

need that error checking such as pyrotechnics and hydraulics.

Figure 12


A DMX signal consists of 512 separate channels of 8 bit data blocks, a Mark before break, and a

break. Figure 12 clearly shows a recorded DMX signal. The logic high seen at the beginning is

the end of the DMX signal and is called the Mark before Break. This mark signals the end of the

DMX stream. The logic low following the Mark is called the Break. This Break preps the devices

that there will be an incoming signal. To determine the difference between each channel there

is a start and stop bit surrounding the 8 bits of data for that channel. The stop bit for the

previous channel is two logic high bits and then the start bit for the next channel following the 2

logics high bits is one logic low bit. After this logic low bit is seen the following 8 bits of data are

the value used for that particular channel.

d. Triangulation Processor

The triangulation processor is responsible for the triangulation calculations which

translate location of the presenter into angles of rotation of the light. To accomplish this, it will

need to communicate both with the parallel DMX processor within the control module and with

the blind node worn by the presenter.

To acquire information regarding the location of the presenter, the triangulation

processor will communicate with the blind node using the internal radio. This processor will

request the “X” and “Y” location

For communication with the DMX processor, we have decided to wire a direct link

between the two processors using one of the I/O ports on each chip. Because of this, they will

be able to pass data as an entire byte. By using this method, data will be updated in a quick and

efficient manner. In addition to the 8-bit port for the passing of data, we will be using two bits

on an additional port to communicate the desired data and if that data is present on the port.

Below is the program flow chart for main program of the triangulation processor. After

initialization, the processor will decide which mode it should be in. If the processor does not

sense that it is in calibration mode, it will constantly poll the location of the presenter from the

blind node. This process relates to the routines within the red dotted lines. Once the processor

has acquired the “X” and “Y” location from the blind node, it will need to calculate the

corresponding angles which will allow the light to point at the presenter. In addition to figuring

the angles, it will compare these angles with a table which will determine the proper 8-bit

binary value which is needed to insert into the commands of the light. Upon completing the


calculations, the triangulation processor will place the first of the two binary values which

represent the rotation of the light into the register linked with the DMX processor. At this

point, the triangulation processor will once again request the location of the presenter from the

blind node and start the process over again.

Main Program for

Triangulation Processor

Set Up

Registers and

Memory

Acquire

DMX Start

Point

Send Start Value

to DMX

Processor when

Requested

In Program

Mode?

Request

X and Y

from Blind

Node

Store First Angle

for DMX

Processor

Calibration

Mode

**NOTE THAT THIS PROGRAM CONSTANTLY

UPDATES THE ANGLES BUT ONLY GIVES THE

ANGLES TO THE DMX PROCESSOR UPON

INTERRUPT. THIS CAN HAPPEN ANY TIME

INSIDE THE DOTTED LINES

Start Angle

Request Interupt

Give Second

Angle Value to

DMX

Processor

End Interupt

PROGRAM FLOW CHARTS FOR TRIANGULATION PROCESSOR

GREEN = GET DATA FROM ANOTHER PROCESSOR

YELLOW = SEND DATA TO ANOTHER PROCESSOR

BLUE = USE INTERNAL PERIPHERALS

Triangulate Angles

The process of triangulation calculations will continuously occur ensuring that the most

recent information about the location of the presenter is available for the DMX processor.

During this process, the first value needed by the DMX processor will be setting in the I/O port,

but we have devised a protocol which will allow the other value to be passed over the port

whenever requested. This process involves handshakes between the two processors. Once the

DMX processor has acquired this first value, it will signal the triangulation processor to store

the second value on the port by setting its handshake bit high. This high signal tells the

triangulation processor to load the second value on the port and, upon completion, the

processor will signal with a voltage high handshake to let the DMX processor know that the

second value is ready for polling. This process will continually repeat unless the triangulation

processor senses that the user has entered the calibration process.

Figure 13


Triangulation Calculations:

There is a need to calibrate the triangulation processor to the parameters of every

installation. We understand that every stage will be of a different size and every light will be

placed at a different location relative to the stage. Because of this, we have created a

calibration process which will allow the system to adjust to these differences. During the

calibration process, the triangulation processor switches from having a passive role in the

control module in which it gives data to the DMX processor upon request to the active role of

acquiring information. In order to calibrate the system, the triangulation processor will need

both the location of the presenter on the stage and the angle of the light when it is pointing at

the presenter. To accomplish this, the processor will wait for a signal from the blind node

stating that it is time to acquire the information.

Retrieving the location of the presenter will be done through communications with the

blind node through the built in radio. To acquire information regarding the rotation of the light,

the triangulation processor will use the linked I/O port between itself and the DMX processor.

The DMX processor will constantly place the most current lateral rotation of the light on this

port. Once the triangulation processor has read this value, it will signal the DMX processor to

pass the vertical angle value by setting the handshake value high. When the DMX processor

returns a signal high handshake, the triangulation processor will collect the second angle value

and wait for the user to indicate another location on the stage is ready to record.

Z

Xx 1tan

Z

Yy 1tan


PROGRAM FLOW CHARTS FOR TRIANGULATION PROCESSOR

GREEN = GET DATA FROM ANOTHER PROCESSOR

Start Calibration

Mode

Wait Untill Ready

to Grab Location

Data

Request

X and Y

from Blind

Node

Acquire First

Angle From

DMX

Processor

Acquire

Second Angle

From DMX

Processor

Flag DMX

Processor for

Second Angle

Acquired 4

Sets of Data?

Calculate Location

of Light

Store Light

Coordinates in

Flash Memory

End Calibration

Mode

NO

Once four different locations on the stage have been recorded, the triangulation

processor will proceed to determine where it is located relative to the stage. This requires

calculating the “X”, “Y”, and “Z” location in space. With the use of four different sets of data,

we have determined that the processor will be able to calculate twelve different values for the

“Z” coordinate and six values for both the “X” and “Y” coordinates. Upon calculation of these

values, the different values for each direction will be averaged to ensure the most accurate

representation of the location of the light.

Calibration Calculations:

Chapter IV: Hardware Layout

We have divided the major hard ware layout we need to do for this project in two three areas:

Reference node: this is the line powered node. For the PCB design, we will include voltage

regulators, antennas, and selector switches. Since we have more than one reference nodes, we

will need to design and obtain many of these layouts.

21

21

tantan

xxZ

tanZxX Z

Yy 1tan

Figure 14


Blind node: unlike the reference nodes, this is completely wireless and thus battery powered. In

addition to the basic hardware layouts that were mentioned above for the reference node, this

will need a battery pack on the PCB design.

Control Module: because of the complexity of this controller, we will need to implement two

CC2430 processors on the hardware implementation. In addition to that we will need

transceivers for the voltage conversion on this controller.

Chapter V: Timeline

Timelines for RAMTrack Auto Tracking Spotlight

August September October November December

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Find Source for Manufacturing of

Create Program for Sending DMX Code

Create Program for Receiving DMX Code

Test Radio Functions and Z-Location Engine

Determine Calculations

for Triangulations

Research DMX and UART Protocol

Create Circuit for Transmission of DMX Code

Create Circuit for Receiving DMX Code

Research Radio and Z-Location Engine

Create Initialization Procedure for Main Program

Design Circuit Board for Reference Nodes

Create Triangulation Code

Determine Hardware Needed

Create Code for Reference Nodes

For timeline, we have split the design process into three different parts. There is the hardware,

triangulation processor, and DMX processor schedules. The main part of each of the timelines

focused on research and requirements of the processors. Since we have several processors

which need to be constantly communicating with each other, we felt there was a need to make

sure every part of the process was researched adequately. Failure to fully understand all of the

used peripherals on the processors would result in future confusion and delays.

Once we understood exactly how the processors can be used, we needed to determine

how the different processors were going to interact with each other and derive protocols for

Figure 15


these interactions. This consisted of determining data transfer protocols and hardware

interconnections.

Finally, we would be ready to start programming the processors. This came with its own

problems. The main problem is the requirement that the flash programmer designed for the

processors required that they be programmed using C language. Since everybody in the group

was new to this language, there have been delays in the programming portion of the schedule

while we create a better understanding of C.

Chapter VI: Conclusion

Where we are at

The project has managed to complete some major milestones in many of our necessary

parts. Currently most of the necessary hardware has been gathered to allow for system testing.

Wireless signal analysis in the theatre atmosphere has been completed which allowed us to

determine necessary broadcast strength and channel to avoid the majority of interference and

still maintain necessary battery lifetimes. We will be broadcasting at +13dB on channel 21 of

the 2.4GHz spectrum. All program flowcharting has been completed. This means that we can

now move onto programming the functions for our processors. The interface to the light is in

design along with the Control Module. The triangulation software is currently being coded and

nearing completion.

Where we are going

Next semester has quite a few significant goals. The first and most important is to

solidify the wireless linking of the blind, reference and control nodes. This is necessary for

obvious reasons and it must also be incredibly stable and reliable. This link is key to having the

carried blind node and interference cannot be tolerated in order to maintain the needed

accuracy. This should not be a problem if we stay on our determined broadcast strengths and

channels. The DMX translation and handling software needs to be coded so that we can handle

signals from the light board and construct the DMX signal for the light. The last piece of the

puzzle will be final hardware design for each module in a prototype stage.


Appendix A – Abbreviations

DMX - Digital MultipleX signal


Appendix B - Budget

Project Allowance: $250 per semester

Current Spending: $0

Remaining Budget: $250

Anticipated Expenses:

PCB Board Manufacturing: TBD

Node Hardware: Approx $100

Extra 2430/2431DVM’s Approx $500

Donations:

ETC: Source Four Revolution $3500

Total: $3500


Appendix C – UCA Signal Analysis PER/1000 RSSI

[db]

Base Case(6 inches) 0 54

5 Feet 0 80

10 Feet 228 98

15 Feet 228 97

20 Feet 583 100

25 Feet 583 100

30 Feet 940 100

35 Feet 940 100

40 Feet 940 100

45 Feet 940 100

50 Feet 940 100

55 Feet 940 100

60 Feet 940 100

65 Feet 940 100

Black Box Theater


5 Feet 0 76

10 Feet 0 88

15 Feet 8 87

20 Feet 0 89

25 Feet 0 89

30 Feet 2 92

Thrust Theater


5 Feet 0 80

10 Feet 0 84

15 Feet 31 91

20 Feet 0 84

25 Feet 3 90

30 Feet 0 93 PER/1000 RSSI [db]

35 Feet 478 98 channel 26, Power 0 333 97

35 Feet channel 26, Power 13

50 87


0 93

35 Feet (hand On the way) channel 11, Power 13

497 100

35 Feet (hand On the way) channel 11, Power 19

1 96

35 Feet (hand On the way) channel 26 Power 13

27 94

35 Feet (body On the way) channel 26 Power 13

0 92


40 Feet 286 96

Back Of the Theater-Back of the Stage 582 100

Back Of the Theater- Front Stage 20 91

Organ Hall


5 Feet 83 90

10 Feet 83 93

15 Feet 0 87

20 Feet 272 98

25 Feet 101 93

30 Feet 35 95

35 Feet 498 97

Art Classroom


5 Feet 69 84

10 Feet 83 83

15 Feet 279 93

20 Feet 292 96

25 Feet 70 90

30 Feet 143 94 PER/1000 RSSI [db]

35 Feet 799 100 High Power, Power 13

63 83

35 Feet High Power, Power 19

53 80

35 Feet channel 26, Power 0 93 646


0 88

Documents

Creation of an Auto-Tracking Theatrical Spotlight · 2008-12-24 · Creation of an Auto-Tracking Theatrical Spotlight First Semester Report ... Figure 3 Version 1.1 Chapter I: Introduction