SPS BACK UP RCS CONTROL

Scanned pages: 1507-1510
# Copyright:  Public domain.
# Filename:  SPS_BACK-UP_RCS_CONTROL.agc
# Purpose:   Part of the source code for Luminary 1A build 099.
#    It is part of the source code for the Lunar Module's (LM)
#    Apollo Guidance Computer (AGC), for Apollo 11.
# Assembler:  yaYUL
# Contact:  Ron Burkey <info@sandroid.org>.
# Website:  www.ibiblio.org/apollo.
# Pages:  1507-1510
# Mod history:  2009-05-27 RSB  Adapted from the corresponding
#        Luminary131 file, using page
#        images from Luminary 1A.
#
# This source code has been transcribed or otherwise adapted from
# digitized images of a hardcopy from the MIT Museum.  The digitization
# was performed by Paul Fjeld, and arranged for by Deborah Douglas of
# the Museum.  Many thanks to both.  The images (with suitable reduction
# in storage size and consequent reduction in image quality as well) are
# available online at www.ibiblio.org/apollo.  If for some reason you
# find that the images are illegible, contact me at info@sandroid.org
# about getting access to the (much) higher-quality images which Paul
# actually created.
#
# Notations on the hardcopy document read, in part:
#
#  Assemble revision 001 of AGC program LMY99 by NASA 2021112-061
#  16:27 JULY 14, 1969

# Page 1507
# PROGRAM NAME:    SPSRCS
# AUTHOR:    EDGAR M. OSHIKA (AC ELECTRONICS)
# MODIFIED:    TO RETURN TO ALL AXES VIA Q BY P. S. WEISSMAN, OCT 7, 1968
# MODIFIED TO IMPROVE BENDING STABILITY BY G. KALAN, FEB. 14, 1969
#
# FUNCTIONAL DESCRIPTION:
#  THE PROGRAM CONTROLS THE FIRING OF ALL RCS JETS IN THE DOCKED CONFIGURATION ACCORDING TO THE FOLLOWING PHASE
#  PLANE LOGIC.
#
#  1. JET SENSE TEST (SPSRCS)
#    IF JETS ARE FIRING NEGATIVELY, SET OLDSENSE NEGATIVE AND CONTINUE
#    IF JETS ARE FIRING POSITIVELY, SET OLDSENSE POSITIVE AND CONTINUE
#    IF JETS ARE NOT FIRING, SET OLDSENSE TO ZERO AND GO TO OUTER RATE LIMIT TEST
#
#   2. RATE DEAD BAND TEST
#    IF JETS ARE FIRING NEGATIVELY AND RATE IS GREATER THAN TARGET RATE, LEAVE
#      JETS ON AND GO TO INHIBITION LOGIC.  OTHERWISE, CONTINUE.
#    IF JETS ARE FIRING POSITIVELY AND RATE IS   LESS  THAN TARGET RATE, LEAVE
#      JETS ON AND GO TO INHIBITION LOGIC.  OTHERWISE, CONTINUE.
#
#  3. OUTER RATE LIMIT TEST (SPSSTART)
#    IF MAGNITUDE OF EDOT IS GREATER THAN 1.73 DEG/SEC SET JET FIRING TIME
#      TO REDUCE RATE AND GO TO INHIBITION LOGIC.  OTHERWISE, CONTINUE.
#
#  4. COAST ZONE TEST
#    IF STATE (E,EDOT) IS BELOW LINE E + 4 X EDOT > -1.4 DEG AND EDOT IS LESS THAN 1.30 DEG/SEC SET JET TIME
#       POSITIVE AND CONTINUE.  OTHERWISE, SET JET FIRING TIME TO ZERO AND CONTINUE.
#    IF STATE IS ABOVE LINE E + 4 X EDOT > +1.4 DEG AND EDOT IS GREATER THAN -1.30 DEG/SEC, SET JET TIME NEGATIVE
#       AND CONTINUE.  OTHERWISE, SET JET FIRING TIME TO ZERO AND CONTINUE.
#
#  5. INHIBITION LOGIC
#    IF OLDSENSE IS NON-ZERO:
#      A) RETURN IF JET TIME AS THE SAME SIGN AS OLDSENSE
#      B) SET INHIBITION COUNTER* AND RETURN IF JET TIME IS ZERO
#      C) SET INHIBITION COUNTER,* SET JET TIME TO ZERO AND RETURN IF SIGN
#         OF JET TIME IS OPPOSITE TO THAT OF OLDSENSE
#    IF OLDSENSE IS ZERO:
#      A) RETURN IF INHIBITION COUNTER IS NOT POSITIVE
#      B) SET JET TIME TO ZERO AND RETURN IF INHIBITION COUNTER IS POSITIVE
#    *NOTE: INHIBITION COUNTERS CAN BE SET TO 4 OR 10 FOR THE P AND UV AXES,
#    RESPECTIVELY, IN SPSRCS.  THEY ARE DECREMENTED BY ONE AT THE BEGINNING OF
# Page 1508
#    EACH DAP PASS.
#
#  THE MINIMUM PULSE WIDTH OF THIS CONTROLLER IS DETERMINED BY THE REPETITION RATE AT WHICH THIS ROUTINE IS CALLED
#  AND IS NOMINALLY 100 MS FOR ALL AXES IN DRIFTING FLIGHT.  DURING POWERED FLIGHT THE MINIMUM IS 100 MS FOR THE
#  P AXIS AND 200 MS FOR THE CONTROL OF THE U AND V AXES.
#
# CALLING SEQUENCE:
#    INHINT
#    TC  IBNKCALL
#    CADR  SPSRCE
#
# EXIT:
#    TC  Q
#
# ALARM/ABORT MODE:  NONE
#
# SUBROUTINES CALLED:  NONE
#
# INPUT:    E, EDOT
#      TJP, TJV, TJU    TJ MUST NOT BE NEGATIVE ZERO
#
# OUTPUT:    TJP, TJV, TJU

    BANK  21
    SETLOC  DAPS4
    BANK

    COUNT*  $$/DAPBU

    EBANK=  TJU
RATELIM2  OCT  00632    # 1.125 DEG/SEC
POSTHRST  CA  HALF

    NDX  AXISCTR
    TS  TJU
    CCS  OLDSENSE
    TCF  POSCHECK  # JETS FIRING POSITIVELY
    TCF  CTRCHECK  # JETS OFF.  CHECK INHIBITION CTR
NEGCHECK  INDEX  AXISCTR    # JETS FIRING NEGATIVELY
    CS  TJU
    CCS  A
    TC  Q    # RETURN
    TCF  +2
    TCF  +1    # JETS COMMANDED OFF.  SET CTR AND RETURN
SETCTR    INDEX  AXISCTR    # JET FIRING REVERSAL COMMANDED.  SET CTR,
    CA  UTIME    # SET JET TIME TO ZERO, AND RETURN
# Page 1509
    INDEX  AXISCTR
    TS  UJETCTR
ZAPTJ    CA  ZERO
    INDEX  AXISCTR
    TS  TJU
    TC  Q
POSCHECK  INDEX  AXISCTR
    CA  TJU
    TCF  NEGCHECK +2
CTRCHECK  INDEX  AXISCTR    # CHECK JET INHIBITION COUNTER
    CCS  UJETCTR
    TCF  +2
    TC  Q    # CTR IS NOT POSITIVE.  RETURN
    TCF  ZAPTJ    # CTR IS POSITIVE.  INHIBIT FIRINGS
    TC  Q    # CTR IS NOT POSITIVE.  RETURN
    OCT  00004
UTIME    OCT  00012
    OCT  00012
OLDSENSE  EQUALS  DAPTREG1
NEGFIRE    CS  ONE    # JETS FIRING NEGATIVELY
    TS  OLDSENSE
    CA  EDOT
    TCF  +4
PLUSFIRE  CA  ONE
    TS  OLDSENSE
    CS  EDOT    # RATE DEAD BAND TEST
    LXCH  A
    CS  DAPBOOLS  # IF DRIFTBIT = 1, USE ZERO TARGET RATE
    MASK  DRIFTBIT  # IF DRIFTBIT = 0, USE 0.10 RATE TARGET
    CCS  A
    CA  RATEDB1
    AD  L
    EXTEND
    BZMF  SPSSTART
    TCF  POSTHRST +3

SPSRCS    INDEX  AXISCTR    # JET SENSE TEST
    CCS  TJU
    TCF  PLUSFIRE  # JETS FIRING POSITIVELY
    TCF  +2
    TCF  NEGFIRE    # JETS FIRING NEGATIVELY
    TS  OLDSENSE  # JETS OFF
SPSSTART  CA  EDOT    # OUTER RATE LIMIT TEST
    EXTEND
    MP  RATELIM1
    CCS  A
    TCF  NEGTHRST  # OUTER RATE LIMIT EXCEEDED
    TCF  +2
    TCF  POSTHRST  # OUTER RATE LIMIT EXCEEDED
    CA  EDOT    # COAST ZONE TEST
# Page 1510
    AD  E
    EXTEND
    MP  DKDB    # PAD LOADED DEADBAND.  FRESHSTART: 1.4 DEG
    EXTEND
    BZF  TJZERO

    EXTEND
    BZMF  +7
    CA  EDOT
    AD  RATELIM2
    EXTEND
    BZMF  TJZERO
NEGTHRST  CS  HALF
    TCF  POSTHRST +1
 +7    CS  RATELIM2
    AD  EDOT
    EXTEND
    BZMF  POSTHRST
TJZERO    CA  ZERO
    TCF  POSTHRST +1

RATELIM1  =  CALLCODE  # = 00032, CORRESPONDING TO 1.73 DEG/SEC
RATEDB1    =  TBUILDFX  # = 00045, CORRESPONDS TO 0.101 DEG/SEC

# *** END OF LMDAP  .015 ***