Review article: locomotion systems for ground mobile robots in unstructured environments

Abstract. The world market of mobile robotics is expected to increase substantially in the next 20 yr, surpassing the market of industrial robotics in terms of units and sales. Important fields of application are homeland security, surveillance, demining, reconnaissance in dangerous situations, and agriculture. The design of the locomotion systems of mobile robots for unstructured environments is generally complex, particularly when they are required to move on uneven or soft terrains, or to climb obstacles. This paper sets out to analyse the state-of-the-art of locomotion mechanisms for ground mobile robots, focussing on solutions for unstructured environments, in order to help designers to select the optimal solution for specific operating requirements. The three main categories of locomotion systems (wheeled - W, tracked - T and legged - L) and the four hybrid categories that can be derived by combining these main locomotion systems are discussed with reference to maximum speed, obstacle-crossing capability, step/stair climbing capability, slope climbing capability, walking capability on soft terrains, walking capability on uneven terrains, energy efficiency, mechanical complexity, control complexity and technology readiness. The current and future trends of mobile robotics are also outlined

Design of a Mars Rover suspension mechanism

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2004Includes bibliographical references (leaves: 71-75)xiii, 75 leavesIt is obvious that rovers are important vehicles of today.s solar system exploration. Most of the rover designs have been developed for Mars and Moon surface in order to understand the geological history of the soil and rocks. Exploration operations need high speed and long distance traversal in a short mission period due to environmental effects, climate and communication restrictions. Several mechanisms have been suggested in recent years for suspensions of rovers on rough terrain. Although their different mechanisms have found a widespread usage in mobile robotics, their low operation speed is still a challenging problem. In this research, a new suspension mechanism has been designed and its kinematic analysis results were discussed. Standard rocker-bogie suspension mechanism, which has been developed in the late 1990.s, has excellent weight distribution for different positions on rough terrain. New design, mostly similar to rocker-bogie suspension system, has a natural advantage with linear bogie motion which protects the whole system from getting rollover during high speed operations. This improvement increases the reliability of structure on field operations and also enables the higher speed exploration with same obstacle height capacity as rocker-bogie. In this thesis study, new bogie mechanism consisted of double-lambda mechanisms, which has been firstly presented by Pafnuty Lvovich Chebyshev in 1869, is solved by analytically to define the positions and singular configurations. A new structural synthesis formula also has been introduced for such suspension mechanisms with lower and higher kinematic pairs. By using structural synthesis methods, a suspension mechanism has been designed with double-lambda mechanism. Equivalent force and moment functions were also derived with equation of motion method. The results are confirmed with the computer analysis made by Visual Nastran 4D®. For this purpose, a computer model has been constructed and assembled with the same design parameters of NASA Mars Exploration Rovers (MER1 and MER2)

An Overview of Legged Robots

The objective of this paper is to present the evolution and the state-of-theart in the area of legged locomotion systems. In a first phase different possibilities for mobile robots are discussed, namely the case of artificial legged locomotion systems, while emphasizing their advantages and limitations. In a second phase an historical overview of the evolution of these systems is presented, bearing in mind several particular cases often considered as milestones on the technological and scientific progress. After this historical timeline, some of the present day systems are examined and their performance is analyzed. In a third phase are pointed out the major areas for research and development that are presently being followed in the construction of legged robots. Finally, some of the problems still unsolved, that remain defying robotics research, are also addressed.N/

Mission design for safe traverse of planetary hoppers

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from department-submitted PDF version of thesis.Includes bibliographical references (p. 116-125).Planetary hoppers are a new class of vehicle being developed that will provide planetary surface mobility by reusing the landing platform and its actuators to propulsively ascend, translate, and descend to new landing points on the surface of a planetary body. Hoppers enhance regional exploration, with the capability of rapid traverse over hundreds to thousands of meters, traverse over hazardous terrain, and exploration of cliffs and craters. These planetary mobility vehicles are fuel limited and as a result are enabled by carrying sensor payloads that require low mass, low volume, and low onboard computational resources. This thesis describes methods for hoppers to traverse and land safely in this constrained environment. The key questions of this research are: - What types of missions will hoppers perform and how does a hopper traverse as part of these missions? - How does a hopper traverse from its current location to a new landing site safely? This thesis: - describes various hopper mission scenarios and considerations for their mission designs. - creates an operational concept for safe landing for the traverse hop mission scenario. - develops a method that can be used to rapidly and safely detect landing areas at long ranges and low path angles. - develops a method to do fine detection of hazards once at the landing area.by Babak E. Cohanim.Sc.D

Contrôle par vecteurs d'influence pour les robots à actionneurs cellulaires binaires

La robotique actuelle est principalement limitée à des tâches de positionnement rapide d'outils. En effet, malgré beaucoup d'efforts de recherche et développement, les robots classiques ont peu de succès pour les tâches d'interaction avec des environnements incertains. De plus, la faible densité massique de puissance des systèmes d'actionnement classique (moteur électrique, réducteur et joint) est contraignante pour les robots mobiles et les mécanismes des véhicules où la masse est critique. Le laboratoire CAMUS explore une nouvelle architecture robotique qui consiste à remplacer les composants complexes (joints, roulements, engrenages, moteurs, etc.) par une structure flexible incluant plusieurs éléments actifs (muscles artificiels). Les avantages d'une telle architecture sont la légèreté, la redondance des actionneurs et la faible impédance passive, des atouts particulièrement intéressants pour la robotique et les mécanismes en aérospatiale. Cette approche est étudiée dans un premier temps en développant des robots constitués d'un corps flexible en polymère incluant plusieurs petits muscles pneumatiques intégrés. Ce mémoire documente le développement d'une méthode de contrôle adaptée à cette nouvelle architecture, car les méthodes classiques ne sont pas applicables. La méthode de contrôle proposée, le contrôle par vecteur d'influence, permet de contrôler une sortie vectorielle (multivariable), comme une position où une force, en recrutant des actionneurs selon leurs vecteurs d'influence sur cette sortie. La méthode ne nécessite pas de modèle analytique car les vecteurs d'influence sont identifiés expérimentalement, ce qui s'avère un atout majeur puisque qu'il est très difficile d'obtenir des modèles précis de systèmes cellulaires. Pour le contrôle en position, le contrôleur proposé utilise une approche probabiliste et un algorithme génétique pour déterminer la combinaison optimale d'actionneurs à recruter. Pour le contrôle de mouvements continus, le contrôleur utilise une approche par surface de glissement et une loi de contrôle indépendante pour chacun des actionneurs. La méthode de contrôle proposée est validée expérimentalement sur un robot prototype utilisant vingt muscles pneumatiques binaires intégrés dans une structure souple en polymère. Les résultats expérimentaux confirment 1'efficacité de la méthode et son habileté à tolérer des perturbations massives et des pannes d'actionneurs