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Soft landing

About: Soft landing is a research topic. Over the lifetime, 741 publications have been published within this topic receiving 5741 citations.


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Journal ArticleDOI
TL;DR: A convexification of the control constraints that is proven to be lossless enables the use of interior point methods of convex optimization to obtain optimal solutions of the original nonconvex optimal control problem.
Abstract: Planetary soft landing is one of the benchmark problems of optimal control theory and is gaining renewed interest due to the increased focus on the exploration of planets in the solar system, such as Mars. The soft landing problem with all relevant constraints can be posed as a finite-horizon optimal control problem with state and control constraints. The real-time generation of fuel-optimal paths to a prescribed location on a planet's surface is a challenging problem due to the constraints on the fuel, the control inputs, and the states. The main difficulty in solving this constrained problem is the existence of nonconvex constraints on the control input, which are due to a nonzero lower bound on the control input magnitude and a nonconvex constraint on its direction. This paper introduces a convexification of the control constraints that is proven to be lossless; i.e., an optimal solution of the soft landing problem can be obtained via solution of the proposed convex relaxation of the problem. The lossless convexification enables the use of interior point methods of convex optimization to obtain optimal solutions of the original nonconvex optimal control problem.

212 citations

Proceedings ArticleDOI
18 Apr 2005
TL;DR: An algorithm for landing hazard avoidance based on images from a single moving camera that is an efficient application of structure from motion to generate a dense elevation map of the landing area and a safe landing site is selected.
Abstract: Future robotic space missions will employ a precision soft-landing capability that will enable exploration of previously inaccessible sites that have strong scientific significance. To enable this capability, a fully autonomous onboard system that identifies and avoids hazardous features such as steep slopes and large rocks is required. Such a system will also provide greater functionality in unstructured terrain to unmanned aerial vehicles. This paper describes an algorithm for landing hazard avoidance based on images from a single moving camera. The core of the algorithm is an efficient application of structure from motion to generate a dense elevation map of the landing area. Hazards are then detected in this map and a safe landing site is selected. The algorithm has been implemented on an autonomous helicopter testbed and demonstrated four times resulting in the first autonomous landing of an unmanned helicopter in unknown and hazardous terrain.

162 citations

Journal ArticleDOI
TL;DR: In this paper, the problem of minimal fuel thrust programming for the terminal phase of a lunar soft landing mission is shown to be equivalent to the minimal time problem for the mission, and the existence of an optimal (minimal fuel) thrust program for the problem is then assured by appealing to existence theorems for time optimal controls.
Abstract: The problem of minimal fuel thrust programming for the terminal phase of a lunar soft landing mission is shown to be equivalent to the minimal time problem for the mission. The existence of an optimal (minimal fuel) thrust program for the problem is then assured by appealing to existence theorems for time optimal controls, and the optimal thrust program is developed by application of the Pontryagin maximum principle. It is shown that the optimal thrust program consists of either full thrust from the initiation of the mission until touchdown, or a period of zero thrust (free-fall) followed by full thrust until touchdown. An approximate switching function which is adequate for a large number of cases is derived, and a preliminary system design is presented.

132 citations

Journal ArticleDOI
TL;DR: The ExoMars program as mentioned in this paper is an ESA-Roscosmos cooperation with some NASA contributions, which includes an orbiting satellite dedicated to the study of atmospheric trace gases to acquire information on possible on-going geological or biological processes, and a European entry, descent and landing demonstrator module (EDM) to achieve a successful soft landing on Mars.
Abstract: The ExoMars program is an ESA–Roscosmos cooperation with some NASA contributions. ExoMars consists of two missions, one in 2016 and one in 2018. The 2016 mission includes an orbiting satellite dedicated to the study of atmospheric trace gases to acquire information on possible on-going geological or biological processes, and a European entry, descent, and landing demonstrator module (EDM) to achieve a successful soft landing on Mars. The orbiter can also provide data communication services for all surface missions landing on Mars until the end of 2022. The 2018 mission is planned to deliver a 300-kg-class rover and an instrumented landing platform to the Martian surface using a landing system developed by Roscosmos. The 2018 mission is to pursue one of the most outstanding questions of our time by attempting to establish whether life ever existed, or is still present, on Mars today. The article gives an overview of the ExoMars program.

119 citations

Journal ArticleDOI
01 Oct 1981
TL;DR: In this paper, the authors measured the vertical reaction force during impact landings following a vertical jump and found that variations between subjects occurred in the magnitude of the peak force over the first 150-200 ms after impact.
Abstract: The vertical reaction force was measured during impact landings following a vertical jump. It was observed that variations between subjects occurred in the magnitude of the peak force over the first 150-200 ms after impact. This period of the landing is termed the impact absorption phase. Two extreme cases of impact landings are taken for analysis. These are referred to as ‘hard’ and ‘soft’ landings, describing the magnitude of the vertical force peak during impact absorption. These differences are produced as a result of the interactions which occur between the individual segments of the human body. The segmental contribution to the total force curve was derived by film analysis techniques. The specific influence of each segment on the total force curve was isolated and made comparable with other segments by using the relative acceleration of the segment mass centre to the lower joint about which it rotates. By using this variable to compare hard and soft landings, it was established that a soft landing ...

94 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202317
202240
202134
202034
201941
201837