summaryrefslogtreecommitdiff log msg author committer range
blob: 43b61010d6f4d282ee1b4630c1e960f0ae23a9a1 (plain)
 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 ``` ``````Thu, 29 Mar 2001: Here's my attempt to estimate the number of floating point operations per second required to implement a reasonable INS on LV2. For the uninterested the answer looks to be about half a million. Basic assumptions: 1. Input consists of 4 accelerometers, and 3 rate-gyros, augmented by periodic GPS and altimeter readings 2. Output consists of full 6 degree of freedom [DOF] position and velocity, therefore 12 numbers 3. Output update frequency 10 Hz 4. Accelerometer input sample frequency 2500 Hz 5. Rate-gyro input sampled at 625 Hz

Further tentative assumptions:

6. Calculations which occur less frequently than 10 Hz do not significantly effect the computational load (Earth-rate, gravity map, normalization) 7. The highest rate integrations are treated adequately as simple sums 8. Multiplication and addition take the same amount of time INS calculation:
Calculation Input Output Clocks Rate [Hz]
velocity increment a_i Delta_v 4 2500
angle increment omega_i Delta_th 3 625
body transformation Delta_th,v th_L, v_L 78 625
coning increment Delta_th,th_L beta_L 12 625
sculling increment a, v v_scul 24 625
summation to m L values m values 4 625
rotation vector a_m, beta_m phi_m 1 100
rotator update phi_m R[b,b-1] 44 100
navigation transform R[b,b-1],R[b,n] R[b,n] 45 100
velocity rotation comp. a_m, v_m v_rot 20 100
body velocity inc. v_(m,scul,rot) v^body 3 10
nav velocity R[b,n],v^body, v_gee v^nav 47 10
gravity Coriolis inc. x^nav, v^nav v_gee 50 10
summation to x v^nav x^nav 9 10