Mike Eichhorn

Solutions for practice-oriented requirements for optimal path planning for the AUV “SLOCUM Glider”

This paper presents a few important practice-oriented requirements for optimal path planning for the AUV “SLOCUM Glider” as well as solutions using fast graph based algorithms. These algorithms build upon the TVE (time-varying environment) search algorithm. The experience with this algorithm, requirements of real missions along the Newfoundland and Labrador Shelf and the idea to find the optimal departure time are the motivation to address the field of research, which is described in this paper. The main focus of this paper is a discussion of possible methods to accelerate the path planning algorithm, without deterioration of the results.

An Obstacle Avoidance System for an autonomous underwater vehicle

This paper describes an Obstacle Avoidance System for an AUV. The specific requirements of the underwater world, the computational capacity and the sensors of the vehicle as well as its manoeuvrability were considered by the choice and the development of the strategies used. Such requirements include the sea current information, the consideration of moving objects, the evasion in 3D and the constrained view of sonar. The system consists of a hierarchical two-level architecture. In the upper level is the course planning, which generates a route for the vehicle to follow. In the lower level, a reactive control system is installed, which guides the vehicle by a sudden emergence of obstacles or deactivated course-planning module.

A new concept for an obstacle avoidance system for the AUV “SLOCUM glider” operation under ice

This paper presents a concept for a control system for an autonomous underwater vehicle under ice using a “SLOCUM” underwater glider. The project concept, the separate working tasks for the next one-and-a-half years and the first results will be presented. In this context the structure of the obstacle avoidance system and a simulator structure with a sensor and environment simulation as well as the interfaces to the glider hardware will be discussed. As a first result of the main research, a graph-based algorithm for the path planning in a time-varying environment (variable ocean field, moving obstacles) will be described.

The European R&D-Project MORPH: Marine robotic systems of self-organizing, logically linked physical nodes

Abstract The MORPH project (FP 7, 2012-2016) advances the novel concept of an underwater robotic system composed of a number of spatially separated mobile robot-modules, carrying complementary resources. Instead of being physically coupled, the modules are connected via communication links that rely on the flow of information among them, i. e. inter-module interactions are enabled by underwater communication networks at distant and close ranges and supported by visual perception at very close range. Without rigid links, the MSV can reconfigure itself and adapt in response to the shape of the terrain, including walls with negative slope. The MORPH concept requires qualitatively new behaviors such as adaptive sensor placement for perception and navigation, as well as environmental modeling in complex environments. On site view planning will lead to a solution well beyond the operational state of the art for underwater cliff surveys and other similar missions. A final demonstration on a vertical cliff, unfeasible automatically with todays technology, will validate the efficacy of the methods developed at the end of the project.

A mission planning system for the AUV “SLOCUM Glider” for the Newfoundland and labrador shelf

This paper presents a system for mission planning for an autonomous underwater vehicle in time-varying ocean currents. The mission planning system is designed for the AUV “SLOCUM Glider” to collect oceanographic data along the Newfoundland and Labrador Shelf. The data will be used in conjunction with a numerical ocean model currently under development by the Department of Fisheries and Oceans Canada. This allows for the validation and the modification of existing ocean current and climate models as well as the design of new models with the aim of improving the accuracy of forecasts. The use of the ocean current forecast data in netCDF format in an ocean current model, the algorithms which consider glider-specific behaviour, details of the programs technical implementation in C++, and, preliminary results will be described.

Modular AUV system for Sea Water Quality Monitoring and Management

The sustained and cost-effective monitoring of the water quality within European coastal areas is of growing importance in view of the upcoming European marine and maritime directives, i.e. the increased industrial use of the marine environment. Such monitoring needs mechanisms/systems to detect the water quality in a large sea area at different depths in real time. This paper presents a system for the automated detection and analysis of water quality parameters using an autonomous underwater vehicle. The analysis of discharge of nitrate into Norwegian fjords near aqua farms is one of the main application fields of this AUV system. As carrier platform the AUV “CWolf” from the Fraunhofer IOSB-AST will be used, which is perfectly suited through its modular payload concept. The mission task and the integration of the payload unit which includes the sensor module, the scientific and measurement computer in the AUV carrier platform will be described. Few practice oriented information about the software and interface concept, the function of the several software modules and the test platform with the several test levels to test every module will be discussed.

A REACTIVE OBSTACLE AVOIDANCE SYSTEM FOR AN AUTONOMOUS UNDERWATER VEHICLE

Abstract This paper presents a reactive/local level of an Obstacle Avoidance System for an Autonomous Underwater Vehicle (AUV). The specific requirements of the underwater world, the computational capacity and the sensors of the vehicle as well as its manoeuvrability were considered by the choice and the development of strategies used. Such requirements include the sea current information, the consideration of moving objects and the constrained view of sonar.

Opportunities to parallelize path planning algorithms for autonomous underwater vehicles

This paper discusses opportunities to parallelize graph based path planning algorithms in a time varying environment. Parallel architectures have become commonplace, requiring algorithm to be parallelized for efficient execution. An additional focal point of this paper is the inclusion of inaccuracies in path planning as a result of forecast error variance, accuracy of calculation in the cost functions and a different observed vehicle speed in the real mission than planned. In this context, robust path planning algorithms will be described. These algorithms are equally applicable to land based, aerial, or underwater mobile autonomous systems. The results presented here provide the basis for a future research project in which the parallelized algorithms will be evaluated on multi and many core systems such as the dual core ARM Panda board and the 48 core Single-chip Cloud Computer (SCC). Modern multi and many core processors support a wide range of performance vs. energy tradeoffs that can be exploited in energy-constrained environments such as battery operated autonomous underwater vehicles. For this evaluation, the boards will be deployed within the Slocum glider, a commercially available, buoyancy driven autonomous underwater vehicle (AUV).

Modelling of the 4-axis kinematic manipulator airarm driven by pneumatic muscle actuators

This paper presents the dynamic modelling of a 4-axis manipulator arm driven by pneumatic muscle actuators. This manipulator, named Air Arm, was developed within a research project of Festos Bio Learning Network 2008. The modelling of the pneumatic and mechanical components of the system is required for the design of the control structure and the determination of the control parameters as well as for the analysis of the system performance. The first part of the paper describes a model, which considers the important effects of the pneumatic plant and the highly nonlinear behavior of the pneumatic muscle. In this context, a readily invertible mathematical model that describes the force-pressure relationship of the muscle will be presented. A description of the kinematic system of the manipulator using Lagrangian mechanics will be presented in the second part of the paper.

Precise Indoor Localization of Multiple Mobile Robots with Adaptive Sensor Fusion Using Odometry and Vision Data

Abstract An accurate, reliable and a cost effective localization is the key feature of self-navigation of autonomous mobile robots. The position and orientation, together known as pose, of the mobile robot can be determined by using certain localization systems. In this work we use the mobile robot system Robotino – a practice-orientated educational and training system offered by Festo Didactic GmbH. For the Robotinos, position determination can be provided by laser scanner for Robotino or Robotino® Northstar System (Festo Didactic GmbH). These existing systems are quite expensive and localization accuracy in certain field dimensions is quite low. In this paper we provide a relatively inexpensive and a more accurate localization system, which combines the strengths of odometry and vision-based localization. The fusion of odometry and vision-based localization data is accomplished with the use of the Extended Kalman Filter (EKF). The resulting localization system delivers better accuracy and more frequent pose information of the mobile robots on the test field.