Source Code

013264,000001: # Copyright: Public domain. 013265,000002: # Filename: LEM_GEOMETRY.agc 013266,000003: # Purpose: A section of Luminary 1C, revision 131. 013267,000004: # It is part of the source code for the Lunar Module's (LM) 013268,000005: # Apollo Guidance Computer (AGC) for Apollo 13 and Apollo 14. 013269,000006: # This file is intended to be a faithful transcription, except 013270,000007: # that the code format has been changed to conform to the 013271,000008: # requirements of the yaYUL assembler rather than the 013272,000009: # original YUL assembler. 013273,000010: # Reference: pp. 327-332 of 1729.pdf. 013274,000011: # Contact: Ron Burkey <info@sandroid.org>. 013275,000012: # Website: www.ibiblio.org/apollo/index.html 013276,000013: # Mod history: 05/10/03 RSB. Began transcribing. 013277,000014: # 05/14/05 RSB Corrected website reference above. 013278,000015: # 2010-08-24 JL Fixed page 330 number. 013279,000016: 013280,000017: # Page 327 013281,000018: 23,2041 BANK 23 013282,000019: 13,2000 SETLOC LEMGEOM 013283,000020: 13,2000 BANK 013284,000021: 013285,000022: 13,2070 30,2000 SBANK= LOWSUPER 013286,000023: 13,2070 E5,1642 EBANK= XSM 013287,000024: 013288,000025: # THESE TWO ROUTINES COMPUTE THE ACTUAL STATE VECTOR FOR LM,CSM BY ADDING 013289,000026: # THE CONIC R,V AND THE DEVIATIONS R,V. THE STATE VECTORS ARE CONVERTED TO 013290,000027: # METERS B-29 AND METERS/CSEC B-7 AND STORED APPROPIRATELY IN RN,VN OR 013291,000028: # R-OTHER,V-OTHER FOR DOWNLINK. THE ROUTINES' NAMES ARE SWITCHED IN THE 013292,000029: # OTHER VEHICLE'S COMPUTER. 013293,000030: 013294,000031: # INPUT 013295,000032: # STATE VECTOR IN TEMPORARY STORAGE AREA 013296,000033: # IF STATE VECTOR IS SCALED POS B27 AND VEL B5 013297,000034: # SET X2 TO +2 013298,000035: # IF STATE VECTOR IS SCALED POS B29 AND VEL B7 013299,000036: # SET X2 TO 0 013300,000037: 013301,000038: # OUTPUT 013302,000039: # R(T) IN RN, V(T) IN VN, T IN PIPTIME 013303,000040: # OR 013304,000041: # R(T) IN R-OTHER, V(T) IN V-OTHER (T IS DEFINED BY T-OTHER) 013305,000042: 013306,000043: 13,2070 COUNT* $$/GEOM 013307,000044: 13,2070 43414 SVDWN2 BOF RVQ # SW=1=AVETOMID DOING W-MATRIX INTEG. 013308,000045: 13,2071 04756 AVEMIDSW 013309,000046: 13,2072 26073 +1 013310,000047: 13,2073 53775 VLOAD VSL* 013311,000048: 13,2074 01521 TDELTAV 013312,000049: 13,2075 57605 0 -7,2 013313,000050: 13,2076 53655 VAD VSL* 013314,000051: 13,2077 01535 RCV 013315,000052: 13,2100 57576 0,2 013316,000053: 13,2101 25220 STOVL RN 013317,000054: 13,2102 01527 TNUV 013318,000055: 13,2103 53257 VSL* VAD 013319,000056: 13,2104 57602 0 -4,2 013320,000057: 13,2105 01543 VCV 013321,000058: 13,2106 77657 VSL* 013322,000059: 13,2107 57576 0,2 013323,000060: 13,2110 15226 STODL VN 013324,000061: 13,2111 01517 TET 013325,000062: 13,2112 01234 STORE PIPTIME 013326,000063: 13,2113 77616 RVQ 013327,000064: # Page 328 013328,000065: 13,2114 53775 SVDWN1 VLOAD VSL* 013329,000066: 13,2115 01521 TDELTAV 013330,000067: 13,2116 57605 0 -7,2 013331,000068: 13,2117 53655 VAD VSL* 013332,000069: 13,2120 01535 RCV 013333,000070: 13,2121 57576 0,2 013334,000071: 13,2122 25720 STOVL R-OTHER 013335,000072: 13,2123 01527 TNUV 013336,000073: 13,2124 53257 VSL* VAD 013337,000074: 13,2125 57602 0 -4,2 013338,000075: 13,2126 01543 VCV 013339,000076: 13,2127 77657 VSL* 013340,000077: 13,2130 57576 0,2 013341,000078: 13,2131 01726 STORE V-OTHER 013342,000079: 13,2132 77616 RVQ 013343,000080: 013344,000081: # Page 329 013345,000082: # THE FOLLOWING ROUTINE TAKES A HALF UNIT TARGET VECTOR REFERRED TO NAV BASE COORDINATES AND FINDS BOTH 013346,000083: # GIMBAL ORIENTATIONS AT WHICH THE RR MIGHT SIGHT THE TARGET. THE GIMBAL ANGLES CORRESPONDING TO THE PRESENT MODE 013347,000084: # ARE LEFT IN MODEA AND THOSE WHICH WOULD BE USED AFTER A REMODE IN MODEB. THIS ROUTINE ASSUMES MODE 1 IS TRUNNION 013348,000085: # ANGLE LESS THAN 90 DEGS IN ABS VALUE WITH ARBITRARY SHAFT, WITH A CORRESPONDING DEFINITION FOR MODE 2. MODE 013349,000086: # SELECTION AND LIMIT CHECKING ARE DONE ELSEWHERE. 013350,000087: 013351,000088: # THE MODE 1 CONFIGURATION IS CALCULATED FROM THE VECTOR AND THEN MODE 2 IS FOUND USING THE RELATIONS 013352,000089: 013353,000090: # S(2) = 180 + S(1) 013354,000091: # T(2) = 180 - T(1) 013355,000092: 013356,000093: # THE VECTOR ARRIVES IN MPAC WHERE TRG*SMNG OR *SMNB* WILL HAVE LEFT IT. 013357,000094: 013358,000095: 13,2133 00041 RRANGLES STORE 32D 013359,000096: 13,2134 57545 DLOAD DCOMP # SINCE WE WILL FIND THE MODE 1 SHAFT 013360,000097: 13,2135 00043 34D # ANGLE LATER, WE CAN FIND THE MODE 1 013361,000098: 13,2136 67401 SETPD ASIN # TRUNNION BY SIMPLY TAKING THE ARCSIN OF 013362,000099: 13,2137 00001 0 # THE Y COMPONENT, THE ASIN GIVIN AN 013363,000100: 13,2140 44206 PUSH BDSU # ANSWER WHOSE ABS VAL IS LESS THAN 90 DEG. 013364,000101: 13,2141 24005 LODPHALF 013365,000102: 13,2142 14005 STODL 4 # MODE 2 TRUNNION TO 4. 013366,000103: 13,2143 24007 LO6ZEROS 013367,000104: 13,2144 24043 STOVL 34D # UNIT THE PROJECTION OF THE VECTOR 013368,000105: 13,2145 00041 32D # IN THE X-Z PLANE 013369,000106: 13,2146 41056 UNIT BOVB # IF OVERFLOW, TARGET VECTOR IS ALONG Y 013370,000107: 13,2147 52432 LUNDESCH # CALL FOR MANEUVER UNLESS ON LUNAR SURF 013371,000108: 13,2150 14041 STODL 32D # PROJECTION VECTOR. 013372,000109: 13,2151 00041 32D 013373,000110: 13,2152 44142 SR1 STQ 013374,000111: 13,2153 00051 S2 013375,000112: 13,2154 14023 STODL SINTH # USE ARCTRIG SINCE SHAFT COULD BE ARG. 013376,000113: 13,2155 00045 36D 013377,000114: 13,2156 77742 SR1 013378,000115: 13,2157 34021 STCALL COSTH 013379,000116: 13,2160 47322 ARCTRIG 013380,000117: # Page 330 013381,000118: 13,2161 43206 PUSH DAD # MODE 1 SHAFT TO 2. 013382,000119: 13,2162 24005 LODPHALF 013383,000120: 13,2163 24007 STOVL 6 013384,000121: 13,2164 00005 4 013385,000122: 13,2165 77634 RTB # FIND MODE 2 CDU ANGLES. 013386,000123: 13,2166 21636 2V1STO2S 013387,000124: 13,2167 25111 STOVL MODEB 013388,000125: 13,2170 00001 0 013389,000126: 13,2171 77634 RTB # MODE 1 ANGLES TO MODE A. 013390,000127: 13,2172 21636 2V1STO2S 013391,000128: 13,2173 01107 STORE MODEA 013392,000129: 13,2174 77776 EXIT 013393,000130: 013394,000131: 13,2175 40110 CS RADMODES # SWAP MODEA AND MODEB IF RR IN MODE 2. 013395,000132: 13,2176 74740 MASK ANTENBIT 013396,000133: 13,2177 10000 CCS A 013397,000134: 13,2200 12204 TCF +4 013398,000135: 013399,000136: 13,2201 53107 DXCH MODEA 013400,000137: 13,2202 53111 DXCH MODEB 013401,000138: 13,2203 53107 DXCH MODEA 013402,000139: 013403,000140: 13,2204 06042 TC INTPRET 013404,000141: 13,2205 77650 GOTO 013405,000142: 13,2206 00051 S2 013406,000143: # Page 331 013407,000144: # GIVEN RR TRUNNION AND SHAFT (T,S) IN TANGNB,+1, FIND THE ASSOCIATED 013408,000145: # LINE OF SIGHT IN NAV BASE AXES. THE HALF UNIT VECTOR, .5(SIN(S)COS(T), 013409,000146: # -SIN(T),COS(S)COS(T)) IS LEFT IN MPAC AND 32D. 013410,000147: 013411,000148: 23,2000 SETLOC INFLIGHT 013412,000149: 23,2000 BANK 013413,000150: 013414,000151: 23,2041 COUNT* $$/GEOM 013415,000152: 013416,000153: 23,2041 47135 RRNB SLOAD RTB 013417,000154: 23,2042 03753 TANGNB 013418,000155: 23,2043 21577 CDULOGIC 013419,000156: 23,2044 41401 SETPD PUSH # TRUNNION ANGLE TO 0 013420,000157: 23,2045 00001 0 013421,000158: 23,2046 57556 SIN DCOMP 013422,000159: 23,2047 14043 STODL 34D # Y COMPONENT 013423,000160: 013424,000161: 23,2050 41546 COS PUSH # .5 COS(T) TO 0 013425,000162: 23,2051 47135 SLOAD RTB 013426,000163: 23,2052 03754 TANGNB +1 013427,000164: 23,2053 21577 CDULOGIC 013428,000165: 23,2054 71406 RRNB1 PUSH COS # SHAFT ANGLE TO 2 013429,000166: 23,2055 72405 DMP SL1 013430,000167: 23,2056 00001 0 013431,000168: 23,2057 14045 STODL 36D # Z COMPONENT 013432,000169: 013433,000170: 23,2060 41356 SIN DMP 013434,000171: 23,2061 77752 SL1 013435,000172: 23,2062 24041 STOVL 32D 013436,000173: 23,2063 00041 32D 013437,000174: 23,2064 77616 RVQ 013438,000175: 013439,000176: # THIS ENTRY TO RRNB REQUIRES THE TRUNNION AND SHAFT ANGLES IN MPAC AND MPAC +1 RESPECTIVELY 013440,000177: 013441,000178: 23,2065 14025 RRNBMPAC STODL 20D # SAVE SHAFT CDU IN 21. 013442,000179: 23,2066 00155 MPAC # SET MODE TO DP. (THE PRECEEDING STORE 013443,000180: # MAY BE DP, TP OR VECTOR.) 013444,000181: 23,2067 40234 RTB SETPD 013445,000182: 23,2070 21577 CDULOGIC 013446,000183: 23,2071 00001 0 013447,000184: 23,2072 73406 PUSH SIN # TRUNNION ANGLE TO 0 013448,000185: 23,2073 77676 DCOMP 013449,000186: 23,2074 14043 STODL 34D # Y COMPONENT 013450,000187: 23,2075 41546 COS PUSH # .5COS(T) TO 0 013451,000188: 23,2076 47135 SLOAD RTB # PICK UP CDU'S. 013452,000189: 23,2077 00026 21D 013453,000190: 23,2100 21577 CDULOGIC 013454,000191: 23,2101 77650 GOTO 013455,000192: 23,2102 46054 RRNB1 013456,000193: # Page 332 013457,000194: # (This page has nothing on it.) 013458,000195: 013459,000196: End of include-file LEM_GEOMETRY.agc. Parent file is MAIN.agc