UK : Robust navigation and path planning for ExoMars rovers

PhD Description: Cranfield University

Under the Aurora Exploration Program, the European Space Agency (ESA) developed the concept and lunched the preparation activities of the ExoMars mission. This mission will start in 2013 whereas the flight will last nearly one year and has as objectives the following:

• To search for signs of past and present life on Mars;
• To characterize the water/geo-chemical environment as a function of depth in the
• shallow subsurface;
• To study the surface environment and identify hazards to future human missions;
• To investigate the planet’s subsurface and deep interior to better understand the evolution and habitability of Mars.

ExoMars will consist of an orbiter, a descent module and a six wheeled rover. The first European rover on Mars will carry a drill that can burrow up to 2 m into the Martian surface allowing its scientific instruments to analyse and sample the soil and search for mineral content, composition and traces of past and present life. Once the descent module carried out by the ExoMars spacecraft achieves landing on Mars surface safely, the rover, which will carry, in addition to the drill, Pasteur scientific instruments along with a sample processing system, will be responsible of the navigation and the exploration of Mars planet.

ExoMars is not the first planet robotic deployment mission since eight successful rovers have been deployed on the Moon and Mars over the previous space experiences, including crewed vehicles as well as remote controlled and autonomous robots. The Lunar Roving Vehicle developed by USA for the Apollo missions and the two Lunokhod lunar rovers developed by USSR were used to explore the Moon. The Mars Pathfinder was used the first Mars rover experiment, and the Mars Excursion Rovers Spirit and Opportunity continue to perform well. are two twin rovers landed on the opposite sides of Mars to search for rocks and soils that hold clues to past water activities on Mars. Future rover missions currently being planned include NASA's Mars Science Laboratory (launch in 2009) and the ESA's ExoMars mission (launch in 2013). Spirit and Opportunity neede to be told by human operators which moves to make next. Because each signal takes half an hour to be relayed to Mars and the results take half an hour to come back, this has made progress on the red planet very slow.

One major advantage that the ExoMars rover will have over Nasa's rovers is that it will be doted with enough intelligence to operate autonomously, making its own decisions about picking the best routes on his way of surface exploration.

Cranfield University, and EADS-Astrium have defined a program of research on "Robust navigation and path planning for ExoMars rovers". This is a three-year program undertaken by a PhD student, and involves original research work either developing entirely new techniques of study, or concerned with the application of novel and existing ideas in new ways.

The area of work proposed by EO group, DCMT, Cranfield University and EADS-Astrium is to be based around the increase of the rover mission autonomy for the ExoMars mission under the Aurora program. It concerns the investigation, the design and the validation of solutions to autonomous robotic navigation and trajectory planning using visual sensors with the affordable minimum of power.

The PhD project has the ambition to tackle autonomy issues, for the ExoMars rovers (and other future robotic exploration missions), in terms of accurate visual navigation and robust path planning concept by proposing innovative integrated methodologies able to be validated with space mission constraints. We will opt for approaches that look into how to improve the localization of the rovers by using robust visual natural features from the environment and then plan robot efficiently online trajectories which full fulfill mission requirements. These approaches will be linked to a robust optimization framework that will be applied to vision, path planning, low level control and estimation strategies guaranteeing the precision of the vehicle localization and motion with safe and power optimal trajectories and fault tolerance to navigation systems issues. The produced position estimates and generated robot trajectories will be robust to outliers and faults. The produced strategies will make sure to take robot kinematics and dynamic constraints in addition to the nature of the terrain where the rovers is progressing in his task. The concept and solutions proposed in this work will be useful not only for the ExoMars rover mission but also for all other missions where autonomy of deployed robotic systems is of crucial importance.

The research work will involve the development of (i) a framework (algorithms and associated design and analysis tools) for the development of robust navigation and path planner of the ExoMars rover, and (ii) a software validated prototype of the robust navigation and path planner.

The research work will incorporate aspects of the following areas of interest:

• Robotic Kinematics and dynamic modeling

• Navigation and robust estimation (based on Linfinty optimization)

• 3D vision (Robust stereo vision) and robust image processing

• Path Planning and decision making of autonomous agents.

• Fault diagnosis and reconfiguration.

• Real time validation taking into account space mission requirements.

Entry Requirements:

For this research studentship, we are seeking a talented graduate, having (or be expected to obtain) at least an upper second class honours degree (first class honours preferred), MSc or equivalent in electrical engineering or computer science. Good mathematical background and experience of robotics, vision, control and path planning, data/information fusion and real time systems would be most desirable.

Eligibility:

We are looking for a high quality European student. The studentship is for three years and provides payment of tuition fees at the UK/EU rate plus a £13,000 per annum (normally tax free) contribution to living expenses. For exceptionally good international students only fees will be considered for payement with no stipend allowed.

To apply send a CV and a covering letter by email as soon as possible to: Dr Aouf n.aouf@cranfield.ac.uk