Automation Glossary

Glossary of commonly used vocabulary in stage engineering and technical theatre, to help amateurs and professionals alike. If you have any definitions you’d like to contribute, please email me and I’ll credit your name at the bottom of the glossary.

Obtained from the Internet.

ABTT

Association of British Theatre Technicians

AC

Alternating Current Acceptance Testing Procedure (ATP) The process of verification after commissioning during which time the system is proven to meet the specified requirements.

ACN

The ESTA Architecture for Control Networks is more formally known as ANSI/ESTA E1.17, Entertainment Technology - Multipurpose Network Control Protocol Suite.

Actuator

A motor or transducer that converts electrical, hydraulic, or pneumatic energy to affect motion. Anti-rake To create or modify a platform to level the rake or slope.

Apron

In a traditional theatre, the part of the stage which projects in front of the curtain; depending on the structure and layout of the theatre, this can often be extended by building out over the pit.

Armature

A revolving structure in an electric motor or generator, wound with the coils that carry the current. Asymmetric Digital Subscriber Line (ADSL) Used to describe high-capacity data transmission, usually in relation to an Internet connection.

Automation

The technique of making an apparatus, a process, or a system operate automatically by mechanical or electronic devices, replacing human labour.

Axis (pl. axes)

Each individual moving element (e.g. a scenery bar, a stage lift, or a flying performer) is defined, in automation terms, as an ‘axis’ (or ‘axes’ in the plural). An axis is controlled with a motor and drive unit. The terms ‘single-axis’ and ‘multi-axis’ are used when referring to one or more of these moving elements. 


Banjo (US)

A horizontal rail, along which a curtain runs (also known as banjo track).

Bar (US Batten)

An aluminium pipe suspended over the stage on which lighting fixtures, scenery or curtains can be hung. Bars can be lowered to the stage (flown in) or raised into a fly tower above the stage (flown out) using a counterweighted fly system or automation. Bars are normally referred to by number e.g. no. 1 bar, no. 2 bar, etc. The no. 1 bar is the one immediately behind the proscenium or the frontmost bar which hangs over the stage in a non-proscenium arch theatre.

BS

British Standard 


Clew plate

Used to join multiple cables, or steel wire rope, at a single point (the clew) to a single larger cable.

Closed loop

Refers to a system which has reference sensors that provide constant feedback to enable machinery etc. to automatically adjust and maintain performance (see also ‘Open loop’).

Commissioning

The process by which an automation system is tuned, programmed and mechanically polished to achieved the smooth and correct motion of each element – this takes place prior to show programming.

Control desk / control console

A piece of automation equipment which sends control signals to the automation system and allows the operator to view system information. The desk (also known as graphical user interface) is designed to allow an operator/programmer to communicate with the automation system in a simplistic manner that can be easily understood.

Counterweight assist system

A system that replaces the human effort of a counterweight system with a winch or other automated system. Counterweight flying system (Arbour US) Method of flying scenery that uses a cradle containing weights to counterbalance the weight of the scenery being moved.

Cue

In automation terms, a pre-recorded sequence of motion (see also ‘State’). 


D:d

Bending ratio of D (diameter of pulley sheaf or drum) to d (diameter of SWR)

DC

Direct Current

Dead (also marks or trims US)

A designated height for a piece of scenery or bar; a label or marker for a physical position or target. Manual flymen use a Dead on a rope as an indication of the position of a scenic piece i.e. all the way in (in view) or out (out of view) or at a mid point. For manual operation, this mark would traditionally be a cotton tape wound through the strands of the rope but this has been replaced more recently with PVC tape or similar. Automation operators label Deads with a number and/or colour system such as ‘Dead 1’.

Dead man’s handle (DMH)

A safety device in the form of a button, handle or similar that must be held down in order to move an axis.

Double-purchased

A system where the cables are reeved over pulleys in such a way that there is a mechanical advantage (of two to one) within the system

Drop pulley

A diverter pulley that ‘drops’ or diverts a rope through a theatre grid.

Dyneema® rope

A superstrong polyethylene fiber that offers maximum strength combined with minimum weight. 


E-Stop, Emergency Stop

A safety button that will immediately stop all axis movement when pressed.

Encoder

A device which measures angular position and can therefore be read by a position control system.

EnDat

Encoder Data, is a proprietary protocol developed by Heidenhain

ESTA

Entertainment Services & Technology Association

Ethernet

Ethernet is the most widely-installed local area network (LAN) technology. Ethernet was named by Robert Metcalfe, one of its developers, after the passive substance called ‘luminiferous ether’ that was once thought to pervade the universe, illustrating the way that Ethernet cabling, also a passive medium, could similarly carry data everywhere throughout the network. 


Factory Acceptance Tests (FATs)

A major project milestone whereby the supplier demonstrates, usually with off-site testing, that the system design and manufacturing meets the contract specifications.

Fit up

Building of the set on stage.

Flats

Movable sections of stage scenery, traditionally consisting of a wooden frame and a decorated panel of wood or cloth but more likely to be composed of steel frames in the modern theatre environment.

Flight case

A case for protecting delicate equipment, such as control desks, during transportation. Smaller cases have handles but larger flight cases usually come on castors for easier management. Some equipment, especially touring kit such as AU:tour, will come with its own flight case.

Flying bar / flybar (Barrel US)

The metal bars to which scenery and lanterns are attached for flying above the stage.

Flyman / flyperson

The operator of the theatre's flying system.

Flytower (Flys or Fly loft US)

Upward extension of the stage walls to allow scenery to be flown up until it is out of sight of the audience; it is also a structural support for the grid. The load on the grid is transferred to the ground via the walls of the theatre. The ideal flytower should be more than twice the height of the proscenium arch, when it is said to have 'full flying height'. For example, The Royal Opera House in London has a triple height flytower, to allow storage of flying pieces in repertory theatre.

Free groups

Axes that move simultaneously but with each axis maintaining independence from the others (see also ‘Locked groups’ and ‘Safe groups’).

Front of House (FOH)

Anything which happens on the audience side of the curtain is said to happen "front of house".

Gearbox

The metal casing enclosing a set of gears (in a motor), in order to provide mechanical advantage and correspondingly reduced motor/brake sizes as well as increasing torque.

Get in/get out

In touring productions, the term 'get in' is used to describe installing and setting up all the touring equipment, scenery and props in the theatre. The reverse is the 'get out'.

Grid

The grid is literally a grid within the roof covering all areas of the stage that require flying, on which the pulleys of a flying system are supported. The grid is usually constructed from metal or wooden beams. Grid is short for ‘gridiron’.

GRT

Gross Registered Tonnes

Hemp

A hemp rope. Hemp or ‘hemp set’ can also refer to a flying system that consists of a number of (hemp) ropes that run over a pulley and are attached to a bar directly (without counterweights); the bar is raised and lowered purely by human effort.

Hydraulic

Of, involving, moved by, or operated by a fluid under pressure. Modern hydraulic systems usually use oil but in the past water was used.

Iron

Safety curtain. 


Jigger ram

A hauling system utilising a hydraulic ram as the prime mover with multiple pulleys mounted at each end and wrapped with one or more wire ropes, such that a given extension of the ram causes two or more times that movement in the rope according to the number of wraps. 


Kabuki drop

This term derives from a traditional Japanese style of theatre. The technique is used for dropping a drape or other lightweight fabric in a quick, single motion from the ceiling for s sudden reveal of the stage or performers. The system traditionally consists of a bar that attaches to a standard flying bar and is able to spin around. The bar has prongs welded to it on which the curtain is hung. On cue, the pole is rotated so that the prongs point downwards and the curtain consequently falls. However, many other Kabuki techniques other than this example are in use in theatre.

Kevlar® rope

A rope spun from light, strong synthetic fibre

ksi

NA measurement of force (1000 psi) 1ksi = 6.89MPa 


Lay

The lay of a rope refers to the direction of the twist of the strands which compose it – if a combination of directions is used the rope may be regarded as having a low rotation, i.e. in normal operation the rotational effect of a rope moving over a pulley is minimised.

Lighting bridge

A walkway above the stage which may be in a fixed or suspended position, on which lights are hung and from which they may be maintained or modified.

Live end / dead end

The live end of a rope is the load bearing end in a termination, such that it directly carries the load of the hanging. The dead end is the returned section of rope coming out of a termination and as such has no direct load applied. The phrase ‘never saddle a dead donkey’ is used by theatre practitioners to remember which way round a Crosby termination ‘dog’ should be applied to a rope.

Load brake

A secondary brake on a winch in direct line with the winch drum, which holds the load should the system fail.

Locked groups

Axes that move simultaneously and are linked together to maintain their relative position. These can be locked by position, velocity, torque or physical linkage (see also ‘Free groups’ and ‘Safe groups’).

LOLER

Lifting Operations and Lifting Equipment Regulations 1998 


Minimum Breaking Load (MBL)

The minimum load at which point an lifting arrangement will fail or yield.

MPa

SI measurement of force in Mega Pascals (1000 Pa or 1000N/m2). 1MPa = 0.145 ksi

Mutually-exclusive

Said of a multi-user operating system in which a safety feature prevents the same axis from being accessed by more than one control desk at a time. 


Open loop

Refers to a system that does not have the capacity for feedback, meaning that errors have to be manually corrected (see also ‘Closed loop’). 


Passerelle

A walkway leading beyond the proscenium arch around the audience side of the orchestra pit. Enables actors to get very close to the audience, and often used in musical theatre or cabaret performances.

Pinion

A small cogwheel that engages or is engaged by a larger cogwheel or a rack (see also ‘Rack and Pinion’).

Pit

The sunken area in front of the stage, which houses the orchestra in a traditional theatre. Some orchestra pits modern theatres have lifts which can be raised to convert the pit area into standing room for live events or to increase the seating in the auditorium.

PLASA

Professional Lighting and Sound Association

Pneumatic

Of, involving, moved by, or operated by compressed air.

Point hoist

A simple winch that provides a single suspension point that can be deployed at any position in a grid.

Programmable Logic Controller (PLC)

A control device designed specifically for industrial machines that perform logical operations but now utilised commonly in stage automation systems.

Proscenium

The area of a modern theatre that is located between the curtain and the orchestra. The proscenium arch is the opening in the wall which stands between stage and the auditorium. A proscenium theatre has the traditional 'picture frame'-style stage area common in older venues.

PUWER1

Provision and Use of Work Equipment Regulations 1998 


Rack

A cabinet, usually of a standard width, into which various components can be fixed to transport or store equipment or house it during use. Racks are often used for touring equipment, and allow easy access to both back and front panels. The height of a rack is measured in 'U's; one rack unit is 1.75" (44.45mm) high and a standard rack is 19" high.

Rack and pinion

A device for the conversion of rotary and linear motion, consisting of a pinion and a corresponding rack.

Raked

Describing a stage or auditorium floor which is raised at the back and slopes downwards towards the front (see anti-rake). The angle of the incline is referred to as the 'rake'. In modern theatres, the audience seating is usually raked rather than the stage.

Ram

The plunger or piston that creates the linear motion of a hydraulic control system. The plunger is forced to extend or retract by compressed oil directed by control valves (this can be controlled by a manual valve or electrically powered solenoid valve).

Reeve

To fasten or fix a rope or rod by passing it through a hole, ring, pulley, or block.

Repertory (abbrev. rep. also stock US)

A theatre in which a resident company presents works from a specified repertoire, usually in alternation or rotation, and each production has a run of limited length, meaning there is normally one production in performance, one in rehearsal, and several in varying degrees of planning. In the British system, even quite small towns in the past would have had a repertory theatre and the resident company would present a different play every week. These days it is more often the remit of opera and ballet companies.

Revolve

A turntable built into the stage floor on which scenery or actors can be positioned and then rotated into view. A revolve can be automated or manually rotated and can also be built on top of an existing stage. 


Safe edge (Astragal US)

A compressible, rubber rim that is used around the edge of a lift, to stop the lift in case of an emergency, thereby protecting limbs that could get trapped. The safe edge may be monitored by contacts closing as the edge is compressed or by resistance change, in which case the system will be programmed to fail.

Safe groups

Axes that are linked to a single piece of scenery but may have differing speeds or paths. This type of group contains an inherent safety relationship so that if one axes fails then they all stop (see also ‘Free groups’ and ‘Locked groups’).

Safe Working Load (SWL)

The load which a lifting device or arrangement can safely lift, suspend or lower. The load represents a mass or force which is much less than that required to make the lifting equipment fail.

Safety Factor (SF)

The ratio of the maximum stress or load which something can withstand to the stress or load which it was designed to withstand under normal operation.

Safety Integrity Level (SIL)

A safety integrity level (SIL) is a measure of safety system performance, in terms of the probability of failure on demand. There are four discrete integrity levels, SIL 1-4. The higher the SIL level, the higher the associated safety level and the lower the probability that a system will fail to perform properly.

Sliders

Usually flat panels of scenery tracked to run across stage manually or automated. Many slider formats have been used in the past with differing sizes, shapes and effects.

Sloat

Stands for 'sliding, lifting, opening, automated trap'

Spotter

Member of stage or automation crew who watches particular equipment moving in order to communicate to the operator if anything is out of the ordinary or if a particular effect needs to be ‘clear to run’.

Sprocket

A toothlike projection arranged on a wheel rim to engage the links of a chain.

Stage deck

A false stage floor which is built over the existing stage floor. A stage deck is generally used if machinery or effects are required to be built into the floor (such as floor tracks or smoke effects). This is often employed during tours as the floor contains all machinery and cable runs required for the touring show and remains discrete from the host theatre’s stage floor.

Stage tracks

Rails in the stage floor or stage deck along which scenery, props, trucks or wagons can be pushed or pulled using automation or manual effort.

Stage truck

A moveable platform that accommodates a 3-D stage set for scene changes and usually runs along stage tracks in the stage deck or stage floor. Radio- controlled trucks are free-moving and are not limited by the positioning of stage tracks.

Stage wagon

A type of stage truck which is larger and usually installed as a permanent feature of the infrastructure of a venue. For example, at the Royal Opera House in London wagons are used to deliver a complete built set to the stage from a storage or rehearsal position.

Star trap

A section of stage floor which can be opened to bring up or take down a performer quickly using a counterweighted or automated elevator under the stage. Originally in the form of upward hinging flaps in a ‘star’ pattern enabling the performer to burst through with dramatic effect – these days drop and slide traps are more usually employed.

State

In automation programming terms, a pre-recorded sequence of motion (also see ‘Cue’).

Steel Wire Rope (SWR)

A cable made of twisted steel, often used to replace hemp ropes due to its durability. The rope can be in an array of formations made up with differing numbers of strands and twists (e.g. 7 by 19 referring to 7 groups of 19 strands). Each group is twisted together and then the groups twisted around each other, to increase tensile strength. In modern theatres, steel wire rope may be replaced by Dyneema rope or Kevlar rope.

Striking

Striking the set (usually referred to as the 'get out' in modern touring theatre) is the dismantling of the set.

System server

A computer that provides central data storage facilities. 


Tabs

Derived from 'tableaux curtains' (a type of curtain that was drawn upwards and outwards also known as a swag curtain) this now refers generally to any house stage curtain/s, including a vertical-lift front curtain (house tabs) and horizontal-draw curtains which meet in the middle and open outwards.

Tech

Abbreviation used for technical rehearsal.

Thrust stage

A stage arrangement which encroaches into the auditorium with the audience seated along three sides.

Torque

A turning or twisting force.

Travelators

A motorised, horizontally-moving belt at stage level, the direction and speed of which can be controlled. Travelators are used for moving scenery or actors onstage or offstage. 


Ultimate Tensile Strength (UTS)

The maximum pulling force to which a material can be subjected without failure.

Universal Serial Bus (USB)

Port to connect hardware to a computer, incorporated into newer control desks for easy transfer of information and increased connectivity

USITT

United States Institute for Theatre Technology