Development of a Cold Gas Propulsion System for the ... - SSL - MIT

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Figure 7-2. CGSE 3-DOF horizontal traverse and roll testing on air bearing. With the air bearing shown in Figure 7-2, the TALARIS hopper hovered about an inch off the floor on a cushion of air, so friction was greatly reduced. The air bearing also freed two degrees of freedom which had been constrained by the wheels, allowing the hopper to roll about its X axis and travel across the entire 2D plane of the floor. Furthermore, although the TALARIS hopper did not have any thrusters aligned with its Y axis, the air bearing did not prevent it from drifting in that direction, so it provided an opportunity to test software compensation for thruster misalignment. Thus, the air bearing allowed for 3-DOF testing, such as the roll and traverse test illustrated in Figure 7-3 below. 108
Figure 7-3. GNC data from 3-DOF test of TALARIS hopper, with 45° roll and horizontal traverse. (a) Angular position. (b) Linear traverse velocity. Figure 7-3 was created with data collected from the hopper’s inertial measurement unit, or IMU. Before the depicted test began, the hopper was placed on the air bearing and set at about a 45° angle to the intended direction of travel. Then during the test, after a calibration period, the vehicle fired its horizontal thrusters in pairs to roll to the desired heading. This maneuver can be seen from about 54 to 61 s in Figure 7-3(a). The hopper then held its new position briefly before performing a horizontal traverse, as shown from about 74 to 78 s in Figure 7-3(b). During the traverse, the hopper drifted slightly off course, probably due to thruster misalignments; however, as shown in Figure 7-3(a), the GNC algorithm executed small roll maneuvers to correct the heading. With a series of tests such as the one illustrated in Figure 7-3, TALARIS horizontal thruster control was successfully validated. The next step was to continue on to validation testing involving the vertical CGSE thrusters. 109
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Development of a Cold Gas Propulsio
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Abstract The TALARIS (Terrestrial A
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Table of Contents List of Figures .
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7 Ongoing and Future Work .........
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Figure 6-6. Identification of thrus
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Notation Acronyms and Abbreviations
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N newton Pa pascal psi pounds per s
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1 Introduction The TALARIS (Terrest
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the idea of hopping was born, and i
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However, as stated before, this doe
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Figure 2-3. Diagram of ACAT lander
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An alternate approach to resolving
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accurate conditions for testing GNC
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Ballistic hops tend to use less pro
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2.3.2 Comparison of Cold Gas and Mo
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Handling propellant There are sever
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and if the cold gas system was foun
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3 TALARIS CGSE Design Framework Aft
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Figure 3-1. Scaling of TALARIS terr
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(3) Providing attitude control Ther
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Figure 3-2 also shows the body coor
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4 Modeling and Flow Control Compone
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4.1.2 Rocket Propulsion Equations L
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variables in equation (4-8) deal wi
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equations. Equation (4-10) was then
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that of helium (0.227 MPa = 32.9 ps
Page 59 and 60: thruster solenoid valve, and chambe
Page 61 and 62: where
Page 63 and 64: discussed later in section 6.3.4, t
Page 65 and 66: The flight profile begins with maxi
Page 67 and 68: hop, any given valve or regulator o
Page 69 and 70: esponse time was an important perfo
Page 71 and 72: directly opens and closes the main
Page 73 and 74: If 1D isentropic flow is assumed, t
Page 75 and 76: 5 Single-Stream Component Testing A
Page 77 and 78: the solenoid valve, and a pressure
Page 79 and 80: As indicated in Figure 5-3, initial
Page 81 and 82: Figure 5-5. CGSE high side as const
Page 83 and 84: Figure 5-7 illustrates several aspe
Page 85 and 86: 6 Full Eight-Thruster Flight System
Page 87 and 88: Figure 6-2. TALARIS CGSE assembled
Page 89 and 90: stream tests revealed that changes
Page 91 and 92: Figure 6-5. Original CGSE control c
Page 93 and 94: other constraints. This was difficu
Page 95 and 96: variables (such as number of thrust
Page 97 and 98: One solution to this problem would
Page 99 and 100: One of the characterization tests w
Page 101 and 102: or more thrusters were firing toget
Page 103 and 104: Table 6-3. Valve timing metrics dur
Page 105 and 106: Figure 6-11. Redesigned CGSE contro
Page 107 and 108: The imaginary simplified thruster c
Page 109: traverse phase of a hop and involve
Page 113 and 114: Tests on this vertical stand demons
Page 115 and 116: control the belay line can be put u
Page 117 and 118: accounting for changes in thrust le
Page 119 and 120: development under the supervision o
Page 121 and 122: documenting progress takes time whi
Page 123 and 124: were encountered, it was harder to
Page 125 and 126: [10] Bryant, K. M., Knight, C. J.,
Page 127 and 128: [31] Canadian Centre for Occupation
Page 129 and 130:
[50] ISA - The Instrumentation, Sys
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