# Copyright: Public domain. # Filename: GIMBAL_LOCK_AVOIDANCE.agc # Purpose: Part of the source code for Comanche, build 055. # It is part of the source code for the Command Module's (CM) # Apollo Guidance Computer (AGC), Apollo 11. # Assembler: yaYUL # Reference: pp. 412-413 # Contact: Onno Hommes . # Website: www.ibiblio.org/apollo. # Mod history: 05/07/09 OH Transcription Batch 1 Assignment # # The contents of the "Comanche055" files, in general, are transcribed # from scanned documents. # # Assemble revision 055 of AGC program Comanche by NASA # 2021113-051. April 1, 1969. # # This AGC program shall also be referred to as Colossus 2A # # Prepared by # Massachusetts Institute of Technology # 75 Cambridge Parkway # Cambridge, Massachusetts # # under NASA contract NAS 9-4065. # # Refer directly to the online document mentioned above for further information. # Please report any errors to info@sandroid.org. # Page 412 BANK 15 SETLOC KALCMON1 BANK EBANK= BCDU # DETECTING GIMBAL LOCK LOCSKIRT EQUALS WCALC WCALC LXC,1 DLOAD* RATEINDX ARATE,1 SR4 CALL # COMPUTE THE INCREMENTAL ROTATION MATRIX DELCOMP # DEL CORRESPONDING TO A 1 SEC ROTATION # ABOUT COF DLOAD* VXSC ARATE,1 COF MXV QUADROT STODL BRATE AM DMP DDV* ANGLTIME ARATE,1 SR 5 STOVL TM BRATE VXSC BIASCALE STORE BIASTEMP # ATTITUDE ERROR BIAS TO PREVENT OVERSHOOT # IN SYSTEM SETGO # STATE SWITCH CALCMAN2 (43D) CALCMAN2 # 0(OFF) = BYPASS STARTING PROCEDURE NEWANGL +1 # 1(ON) = START MANEUVER ARATE 2DEC .0022222222 # = .05 DEG/SEC 2DEC .0088888889 # = .2 DEG/SEC 2DEC .0222222222 # = .5 DEG/SEC 2DEC .0888888889 # = 2 DEG/SEC $22.5 DEG/SEC ANGLTIME 2DEC .000190735 # = 100B - 19 # MANEUVER ANGLE TO MANEUVER TIME QUADROT 2DEC .1 # ROTATION MATRIX FROM S/C AXES TO CONTROL # Page 413 2DEC 0 # AXES (X ROT = -7.25 DEG) 2DEC 0 2DEC 0 2DEC .099200 # =(.1)COS7.25 2DEC -.012620 # =-(.1)SIN7.25 2DEC 0 2DEC .012620 # (.1)SIN7.25 2DEC .099200 # (.1)COS7.25 BIASCALE 2DEC .0002543132 # = (450/180)(1/0.6)(1/16384)