Attitude stabilization of a quadrotor aircraft

The quadrotor aircraft has seen a growing interest in the research community over the past few years, with a focus on modeling and control however. Early rotating wing aircraft pioneers designed similar four-rotor aircraft with varied success over a number of years. With the introduction of new lightweight sensors for measuring the attitude and angular velocity of a rigid body, model sized versions of traditional helicopters with autonomous capabilities have emerged, with the advantage of vertical take-off and landing (VTOL) over fixed wing aircraft. The quadrotor aircraft, with its symmetrical design, has a potential advantage with respect to the traditional helicopter in terms of maneuverability and mechanical simplicity. In fact, autonomous unmanned aerial vehicles (UAV’s) have gained popularity for their numerous potential applications where human interaction is difficult or hazardous. Attitude stabilization, which could be considered the most important component for flight control, is essential for autonomous or even pilotable aircraft such as the quadrotor, as their designs are inherently unstable. As the literature suggests, a number of control algorithms have been proposed for the attitude control of a rigid body. In this thesis, a control strategy for the attitude stabilization of the quadrotor aircraft as well as some simulation and experimental results are presented

The Scottish economy [July 1975]

Scottish GDP in real terms increased in 1974, and our central estimate for this increase is £4106m at constant prices; this represents an increase of 0.8% over 1973. Modest though this is, in a year in which UK GDP as a whole actually declined it can be regarded with some satisfaction. Indeed our qualitative judgement is that the statistical forecast is, if anything on the conservative side, though as yet our forecasting methods are insufficiently developed to include these additional indicators of activity levels. Trends in GDP during the first quarter of 1975 are more difficult to predict

Outlook and appraisal [August 1984]

Growth in the British economy came almost to a halt during the first half of this year. As a result , even a speedy resolution of the coal dispute would be unlikely to push the GDP growth rate this year above 2.5 Though much of July's interest rate increase has already been reversed, it is likely to prove more difficult to reverse the effects on the retail price index and thus attain the goal of H.5% inflation at the end of the year. The uncompetitive nature of the housing finance market makes a speedy and full unwinding of the recent rise in mortgage rates unlikely

The Scottish economy [August 1984]

Throughout much of the last two years the official view has been that the Scottish recession was less severe than that experienced in the United Kingdom as a whole. Indeed, the Secretary of State has proclaimed to a variety of audiences, including the House of Commons, that Scotland was, and still is , leading the country out of recession. This diagnosis has not met with universal approval, as it appears to be founded primarily on the growth of the Scottish electronics sector and on the smaller proportionate rise in unemployment which has occurred in Scotland than in Britain as a whole. This latter fact is not particularly surprising as the pre-recession level of unemployment in Scotland was markedly above that of the rest of Britain

Foreign investment in Scotland

A significant feature of the UK economy throughout the post-war period has been the growth in direct foreign investment in manufacturing industries. For the host nation the main benefits are employment creation, income generation and import reduction or export expansion. Scotland has been particularly successful in attracting the lion's inward investment for example in the period 1945- 1965 a total of 108,500 jobs were created by foreign firms setting up manufacturing units in the despite its size, obtained 46,221 (42.6%), whereas the second most SE England, gained only 16,926 (15.6%). The reasons for this success have been attributed primarily to a combination of the availability of labour in Scotland, the financial inducements offered by central government as part of regional policy and, the undoubted attraction of the environment, notably of course golf courses, for foreign businessmen. This brief paper explores the nature of Scotland's direct foreign investment and the reasons for its success

The British economy [August 1985]

The pace of economic growth rose above the underlying growth rate in the first half of 1985 as a consequence of recovery from the miners' dispute and first quarter bunching of investment expenditure. In response to higher interest rates and the Chancellor's continuing commitment to the Medium Term Financial Strategy, sterling has strengthened and has remained resilient in the face of continuing uncertanties concerning oil prices. Output is set to grow by more than 3% this year before falling back as the impetus of the rebound from the miners' dispute diminishes and investment expenditure slackens. This slowdown in activity is likely to be reinforced by the current levels of the exchange rate and of interest rates

The Scottish economy [November 1985]

With the inauguration of the quarterly Scottish Business Survey (SBS) in September 1984 there are now two regular up-to-date indicators of trends in the Scottish industrial sector. The combination of the new survey and the long-standing CBI Industrial Trends Survey provides a comprehensive assessment of trends in Scottish industry

The world economy [August 1985]

The recovery in the world economy which began in 1982 now appears to be moving out of its fastest growth phase. With the US economy growing more slowly in the first half of 1985 than in the corresponding period of 1984, the previous marked differences in growth rates between the US and the European economies are being eroded. Indeed, a number of European countries look set to achieve faster growth during 1984 than the US. Largely due to slower US growth, world trade is likely to expand this year by around 5J-6S as compared to 9% last year. The Bonn economic summit in May and subsequent policy statements provide no indications that the slackening momentum in the world economy is to be compensated for by reflation elsewhere