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Lunar Module Attitude Controller Assembly Digital Input Processing José Portillo Lugo jportillo34@hotmail






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Lunar Module Attitude Controller Assembly Digital Input Processing José Portillo Lugo jportillo34@hotmail.com. Uses the Apollo Guidance Computer Counter Interrupt system. Two types of Input to the Apollo Guidance Computer: PROPORTIONAL
Lunar Module Attitude Controller Assembly Digital Input Processing José Portillo Lugo jportillo34@hotmail

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Slide 1

Lunar Module Attitude Controller AssemblyDigital Input ProcessingJosé Portillo Lugojportillo34@hotmail.com

Slide 2

Uses the Apollo Guidance Computer Counter Interrupt system.

Two types of Input to the Apollo Guidance Computer:

PROPORTIONAL

Make use of the LM Guidance Computer Counter Interfaces for Analog-to-Digital conversion, and Transformer-based Interface circuit.

Used for Rate Command Augmentation Mode.

DISCRETE

Make use of the LM Guidance Computer discrete Interface Channel bits.

Used for Pulse Mode.

Used for Man-in-the-Guidance-Loop capabilities.

Lunar Module Attitude Controller AssemblyDigital Input Processing

Slide 3

Proportional Input Processing

Slide 4

1958: NACA technical paper describing “Systems that Command Velocity” as

feedback control concept.

Simulator investigation of Command Reaction Controls - Holleman, Euclid C.; Stillwell,

Wendell H. - NACA RM H58D22 - April 14, 1958.

1959: Development of a Self-Adaptive flight control system: the X-15 research

1960: vehicle.

1963: Development of an Analog Rate Command Augmentation/Attitude-Hold

1964: control system for the Gemini Spacecraft.

1964: AIAA conference paper describing a Rate Command and Acceleration

Comand systems implemented in the Langley Research Center Gemini-

Agena Docking Simulators.

Full-Scale Gemini-Agena Docking using Fixed and Moving base Simulators - Hatch, Howard G.;

Riley, D. R.; Cobb, J. - AIAA paper 64-334 - June-July 1964.

1964: Apollo lunar program: decision to implement a “Digital Autopilot” for the

Lunar Module Primary Guidance System.

Manual Rate Command Augmentation SystemsA brief chronology

Slide 5

1966: NASA LRC technical paper describing a Rate Command and

Acceleration Command electronic control system for control of the

Lunar Landing Research Vehicle.

Flight Tests of a Manned Rocket-Powered Vehicle Utilizing the Langley Lunar Landing

Research Facility - O’Bryan, Thomas C. - Presented at AIAA Guidance and Control Specialists

Conference - Siattle, Washington - August 1966.

1966: NASA technical paper describing a Rate Command Augmentation

system (fly-by-wire bang-bang) implemented in the DFRC lunar Landing

Research simulation vehicle.

Operational experience with the Electronic Flight control Systems of a lunar-Landing

Research vehicle - Jarvis, Calvin R. - NASA TN D-3689 - July 5, 1966.

1966: Grumman Aircraft developed a Lunar Module Simulator for development

and testing purposes. An Analog processing for the Hand Controller was

implemented.

Lunar Module Hover and Landing, Separation and Docking Simulation - Greene S.; Russo, J. -

Presented at AIAA Flight Test, Simulation and Support Conference - Cocoa Beach, Florida -

February 6-8, 1967.

Manual Rate Command Augmentation SystemsA brief chronology

Slide 6

1968: Development of a Rate Command Augmentation system embedded into

the LGC Digital Autopilot.

1969: First flight test of the Lunar Module Digital Autopilot, including its manual

Rate Command Augmentation/Attitude-Hold capability.

Apollo 9 Mission in earth orbit.

1969: First Lunar Landing operation for the Lunar Module Digital Autopilot.

Apollo 11 Mission. It includes an more complete Manual Rate Command Augmentation System.

Manual Rate Command Augmentation SystemsA brief chronology

Slide 7

Embedded into the Digital Autopilot Software.

Shows all the advantages of Digital Control System implementations over Analog Control System implementations: input data processing follows conditional paths, switching points, and storage for external entered and internal fixed memory constant parameters.

Make use of the Counter Interrupt system of the Apollo Guidance Computer.

External

Control

Parameters

Proportional Commands

Apollo Lunar Module Digital Manual Rate Command Augmentation System

Slide 8

“Start Gating” bit

“A” Circuit

10 cps

HI

(proportional)

RHCCTR Counter

LO

Out-Of-Detent Inbit (Channel 31)

10 cps

Apollo Lunar Module Digital Manual Rate Command Augmentation System

Interface Level

Digital Autopilot

DETENTCK EXTEND

READ CHAN31

TS CH31TEMP

MASK BIT15

EXTEND

BZF RHCMOVED

CAF OURRCBIT

MASK DAPBOOLS

EXTEND

BZF PURGENCY

RHCMOVED CS RCSFLAGS

MASK BIT9

ADS RCSFLAGS

CA OURRCBIT

MASK DAPBOOLS

EXTEND

BZF JUSTOUT - 1

RATERROR CA CDUX

TS CDUXD

Slide 9

Two steps:

INITIALIZATION PASS.

NORMAL RATE COMMAND PASS.

Two Control Laws were employed for Manual Rate Command Augmentation:

DIRECT RATE

Used each time the change in “Commanded Rate” between two Digital Autopilot passes exceeds a “Breakout Level” Switch.

Computes Jet-on time based only in Rate Error information: do it fast!

To damp vehicle Rates below a “Target” Dead Band (before return control to the Attitude Hold Autopilot).

Used on a per-Axis base.

PSEUDO-AUTOMATIC

Used while there is no Manual input. To Hold an Attitude.

Computes Jet-on time based upon Rate and Attitude Error information.

Uses a Phase-Plane logic to exercise Control.

It can achieve very small Commanded Rates.

Used on a per-Axis base to prevent Attitude drift about uncommanded Axes.

Apollo Lunar Module Digital Manual Rate Command Augmentation System

Slide 10

Commanded

Rate Exceeds

Breakout Level?

Apollo Lunar Module Digital Manual Rate Command Augmentation SystemControl Law Selection

Scaling

yes

+

ACA

Counter

DIRECT RATE

Control Law

-

no

PSEUDO-AUTOMATIC

Control Law

MCR

Breakout

Level Switch

Dead Band Switch

Control

Flow

Flags

  • Digital Autopilot Control Parameters:

  • Constant Values in Rope Memory

  • Entered in-flight by crew

  • Flags set ON/OFF by previous iterations

Slide 11

Discrete Input Processing

Slide 12

Make use of the Guidance Computer Input Channel.

Provides a way to input low Rate Commands as well as Man-in-the-Guidance-Loop capabilities.

Discrete Commands

External

Control

Parameters

Apollo Lunar Module Digital Manual Minimum Impulseand LPD Redesignator

Slide 13

Out-Of-Detent Inbit (Channel 31)

10 cps

Interrupt 10 (Redesignator Trap)

“D” Circuit

Discrete

Inbit (Channel 31)

Minimum Impulse

& Discrete LPD

Apollo Lunar Module Digital Manual Minimum Impulseand LPD Redesignator

Interface Level

Digital Autopilot

CA L No

MASK -AZBIT

CCS A

-AZ CS AZEACH

ADS AZINCR1

CA L

MASK +AZBIT

CCS A

+AZ CA AZEACH

ADS AZINCR1

CA L

MASK -ELBIT

CCS A

-EL CS ELEACH

ADS ELINCR1

CA L

MASK +ELBIT

CCS A

+EL CA ELEACH

ADS ELINCR1

TCF RESETRPT

Fixed-Address Instruction

4050 DXCH ARUPT

4051 CA RUPT10BB

4052 XCH BBANK

4053 TCF PITFALL

Slide 14

Two Discrete Inputs:

MINIMUM IMPULSE

Enables the crew to perform economical low Rate maneuvers.

Embedded into the Digital Autopilot Software.

LM Guidance Computer Channel 31 includes the Input bits.

LPD REDESIGNATOR

Enables the crew to enter into the Lunar Landing Automatic Guidance Loop.

Embedded into the Landing Approach Phase Guidance Software (the so called “Manual Steering Section”).

LM Guidance Computer Channel 31 includes the Input bits.

LPD Redesignation Input Commands are processed by the Interrupt system.

Apollo Lunar Module Digital Manual Minimum Impulseand LPD Redesignator

Slide 15

Uses the Apollo Guidance Computer Counter Interrupt system.

Two types of Input to the Apollo Guidance Computer:

PROPORTIONAL

Make use of the LM Guidance Computer Counter Interfaces for Analog-to-Digital conversion, and Transformer-based Interface circuit.

Used for Rate Command Augmentation Mode.

DISCRETE

Make use of the LM Guidance Computer discrete Interface Channel bits.

Used for Pulse Mode.

Used for Man-in-the-Guidance-Loop capabilities.

Lunar Module Attitude Controller AssemblyDigital Input ProcessingIn resume

Slide 16

Handling Qualities for Pilot Control of Apollo Lunar-LandingSpacecraft – Cheatham, D. C.,Hackler, C. T. - Journal ofSpacecraft and Rockets, Vol. 3, No. 5, May 1966, pp. 632-638.

MIT's Role in Project Apollo - Volume III – Computer Subsystem – Hall, Eldon C. - August 1972.

Manual Attitude Control of the Lunar Module – Stengel, Robert F. – AIAA paper 69-892 –August 1969.

Apollo Experience Report - Crew Station Integration - Volume III– Spacecraft Hand ControllerDevelopment - Wittler, rank E. – Lyndon B. Johnson Space Center, Huston Texas 77058 - March 1975.

A Manual Retargeted Automatic Landing System for the Lunar Module - Klumpp, Allan R. – Journal of Spacecraft and Rockets - Volume 5 - Number 2 -February 1968 - pp 129-138.

Lunar Module Digital Autopilot - Widnall, William S. - Journal ofSpacecraft - Vol. 8, No. 1- January 1971.

Lunar Module Attitude Controller Assembly Input Procesing – Portillo Lugo, José R. – MAPLD 2004 Conference paper – September 2004.

References


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