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首頁(yè)> 外文學(xué)位 >Gyroscope spin axis direction control for the Gravity Probe B satellite.
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Gyroscope spin axis direction control for the Gravity Probe B satellite.

機(jī)譯：重力探測(cè)器B衛(wèi)星的陀螺儀旋轉(zhuǎn)軸方向控制。

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The Gravity Probe B Relativity Experiment (GP-B) is a joint NASA/Stanford University orbiting astrophysics experiment, under development, to test two predictions of Einstein's theory of general relativity, the geodetic and frame-dragging effects, using orbiting, ultra-precise, mechanical, electrically-suspended gyroscopes (ESVG) carefully isolated from Newtonian torques. General relativity predicts that the gyroscopes' spin axes will precess with respect to a distant inertial reference frame at a rate of 6.6 arc-sec/year for the geodetic effect, and 42 marc-sec/year due to frame-dragging in the planned orbit. To achieve the needed levels of measurement precision, the gyroscopes' axes must be aligned to within 10 arc-sec of the line-of-sight to a distant guide star.; Presented is a technique by which the initial orientation of each gyroscope can be controlled through the use of residual torques generated by the gyroscope' s electrostatic suspension system. The electrostatic torques acting on the gyroscope depend on the rotor shape, which is nominally spherical but also contains small manufacturing asphericities and a spin-induced bulge. These torques are averaged by rotor spin to take on a simple form: they cause the gyroscope to precess about the suspension electrode axes.; Orientation control torques are applied by introducing additional suspension voltages to the electrodes in combinations which do not exert a force on the gyroscope, but do generate a torque. A control system was developed to use these torques to drive the spin axis to a desired orientation in minimum-time using a bang-bang actuation scheme. A net torque identification scheme was also created to monitor polhode-induced modulations of the spin-averaged torques. This information was used by the orientation control system to keep the spin axis on a minimum-time trajectory.; Laboratory experiments confirmed the validity of the spin-averaged torque models and gave a proof-of-principle of the effectiveness of the bang-bang spin axis orientation control system. Under active orientation control, the polhode modulations of the spin-averaged torques were readily measured using the proposed identification technique. The net result of the tests confirm that the spin axes of the gyroscope may be oriented using these techniques to the accuracy required for the GP-B experiment.
機(jī)譯：重力探測(cè)器B相對(duì)論實(shí)驗(yàn)（GP-B）是美國(guó)宇航局/斯坦福大學(xué)聯(lián)合進(jìn)行的天體物理學(xué)軌道實(shí)驗(yàn)，正在開(kāi)發(fā)中，用于測(cè)試愛(ài)因斯坦的廣義相對(duì)論的兩個(gè)預(yù)測(cè)，即大地測(cè)量和框架拖曳效應(yīng)，使用軌道超精密技術(shù)，機(jī)械的，電懸掛的陀螺儀（ESVG）與牛頓扭矩仔細(xì)隔離。廣義相對(duì)論預(yù)測(cè)，陀螺儀的自轉(zhuǎn)軸將相對(duì)于遙遠(yuǎn)的慣性參考系進(jìn)動(dòng)，其大地影響的速率為6.6弧秒/年，而由于計(jì)劃中的軌道被拖曳，速率為42 marc-sec /年。 。為了達(dá)到所需的測(cè)量精度水平，陀螺儀的軸必須與距離遙遠(yuǎn)的恒星的視線(xiàn)對(duì)準(zhǔn)10弧秒以?xún)?nèi)。提出了一種技術(shù)，通過(guò)該技術(shù)可以通過(guò)使用由陀螺儀的靜電懸架系統(tǒng)產(chǎn)生的殘余扭矩來(lái)控制每個(gè)陀螺儀的初始方向。作用在陀螺儀上的靜電轉(zhuǎn)矩取決于轉(zhuǎn)子的形狀，該轉(zhuǎn)子的形狀通常為球形，但也包含較小的制造非球形度和自旋引起的凸起。這些扭矩通過(guò)轉(zhuǎn)子旋轉(zhuǎn)取平均值，以簡(jiǎn)單的形式表示：它們使陀螺儀繞懸架電極軸進(jìn)動(dòng)。通過(guò)將附加的懸浮電壓引入電極中來(lái)組合施加方向控制扭矩，這些電壓不會(huì)在陀螺儀上施加力，但會(huì)產(chǎn)生扭矩。開(kāi)發(fā)了一種控制系統(tǒng)，可使用這些扭矩在最小時(shí)間內(nèi)使用爆炸驅(qū)動(dòng)方案將旋轉(zhuǎn)軸驅(qū)動(dòng)到所需的方向。還創(chuàng)建了凈扭矩識(shí)別方案來(lái)監(jiān)視自旋平均扭矩的多極感應(yīng)調(diào)制。定向控制系統(tǒng)使用此信息將旋轉(zhuǎn)軸保持在最小時(shí)間軌跡上。實(shí)驗(yàn)室實(shí)驗(yàn)證實(shí)了自旋平均轉(zhuǎn)矩模型的有效性，并給出了自旋自旋軸方向控制系統(tǒng)有效性的原理證明。在主動(dòng)定向控制下，使用所提出的識(shí)別技術(shù)可以很容易地測(cè)量自旋平均轉(zhuǎn)矩的極化調(diào)制。測(cè)試的最終結(jié)果證實(shí)，使用這些技術(shù)可以將陀螺儀的旋轉(zhuǎn)軸定向到GP-B實(shí)驗(yàn)所需的精度。

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