Stelzer, R.; Jafarmadar, K.; Hassler, H.; Charwot, R. (2010): "A Reactive Approach to Obstacle Avoidance in Autonomous Sailing", in Proceedings of International Robotic Sailing Conference, pp. 34-40, Kingston, Ontario, Canada.
This paper presents a reactive approach to obstacle avoidance for autonomous sailboats. It is an extension to the short course routing method published by Stelzer and Pröll in 2008 which enables it to deal with obstacles in real-time. First simulation results are promising. The algorithm enables an autonomous sailboat to circumnavigate differently sized obstacles under various wind conditions successfully.
- Influence of obstacles on polar diagram
Klinck, H.; Stelzer, R.; Jafarmadar, K.; Mellinger, D.K. (2009): "AAS Endurance: An autonomous acoustic sailboat for marine mammal research", in Proceedings of International Robotic Sailing Conference, pp. 43-48, Matosinhos, Portugal.
This paper presents a joint research project of the Austrian Society for Innovative Computer Science, Austria and Oregon State University, USA which is intended to be realised within the next three years. The aim of the project is to develop an autonomous sailboat for passive acoustic monitoring of marine mammals and mitigation of human impacts on them. Performance tests of the autonomous acoustic sailboat - AAS Endurance - will include an open sea transect of at least one month duration. The work presented here discusses shortcomings of current ways of acoustic marine mammal monitoring and outlines advantages of a robotic sailboat for this task, as well as problems to be solved with this new technology.
- Comparison of the spatial and temporal coverage of ship transects (dotted line) and stationary recorders (dashed circles)
Stelzer, R.; Jafarmadar, K. (2009): "Communication Architecture for Autonomous Sailboats", in Proceedings of International Robotic Sailing Conference, pp. 31-36, Matosinhos, Portugal.
Although an autonomous sailboat can operate without human intervention a data link between boat and shore is necessary. During development a reliable connection for monitoring, debugging, and remote control in case of emergency is essential. When used for long-term observation tasks the operator on shore is keen to receive real-time measurement data. A three-stage communication system for autonomous sailboats has been designed, implemented and tested successfully. It combines wireless LAN, GPRS/UMTS and satellite communication for a reliable data link between shore and sailboat.
- Third stage - satellite communication
Stelzer, R.; Pröll, T. (2008): "Autonomous Sailboat Navigation for Short Course Racing", in Elsevier Journal of Robotics and Autonomous Systems, Vol. 56 (7), pp. 604-614.
The paper presents a compact method to calculate a suitable route for a sailboat in order to reach a specified target. The calculation is based on the optimisation of the time-derivative of the distance between boat and target and features a hysteresis condition, which is of particular importance for beating to windward. The algorithm provides an answer to the perennial question when to tack on upwind courses. Further, it immediately adapts to varying wind conditions. The resulting routes for different conditions are analysed on the basis of a simulation featuring a mathematical boat model. Experiments have been carried out using an unmanned and autonomously controlled sail boat. The navigated route agrees well with the simulation results.
- Routeing Example (compares real test run with simulation results)
Stelzer, R.; Pröll, T.; John, R.I. (2007): "Fuzzy Logic Control System for Autonomous Sailboats", in Proceedings of IEEE International Conference on Fuzzy Systems, pp. 97-102, London, UK.
Sailing experts can explain basic sailing skills by rules about how to steer sails and rudder according to direction of target and wind. This paper describes how to transform the sailor’s knowledge into Mamdani type fuzzy inference systems. The proposed system controls two actuators – rudder and sails – even during tack and jibe. In combination with an automatic weather routeing system the sailboat is able to reach any target completely autonomously. Experiments on a demonstration sailboat have shown excellent results. Detailed log data analysis shows manoeuvres carried out as expected by sailing experts.
- Tack Example
- Jibe Example
Stelzer, R.; Jafarmadar, K. (2007): "A Layered System Architecture to Control an Autonomous Sailboat", in Proceedings of TAROS 2007, Aberystwyth, UK.
A four layered control architecture is presented for an autonomous sailboat combining both reactive and planner-based approaches. The system allows autonomous sailing, where routeing, navigation and carrying out the manoeuvres run automatically and directly on the boat. Various sensors observe the highly dynamic environment and provide measured data to the control system, which steers rudder and sails. The four layers are responsible for strategic long term routeing, short course routeing, manoeuvre execution, and reflexes in case of emergency. All four layers are executed in parallel. They access sensor data directly and generate prerequisites for the succeeding, subordinate layer. Experiments using a yacht model have been carried out to demonstrate feasibility and suitability of the presented approach. Detailed log data analysis from actual sailing trips show a steering behaviour as expected by sailing experts.
- Roboat System Architecture
Stelzer, R.; Jafarmadar, K. (2007): "Simple Communication Protocol for Rapid Robot Prototyping", in Proceedings of Humanoid and Service Robotics Conference", Kosice, SK.
Aim of the method presented in this paper is to provide a simple and unique communication protocol for a wide variety of sensors and actuators. All of the devices are equipped with a microcontroller in order to translate the proprietary device dependent protocol into the protocol presented here, named Simple Sensor Network (SSN). Due to the very simple commands to request data from a sensor respectively to send data to an actuator via RS232, it is an appropriate way for a novice to get in touch with robotics without the need of expert knowledge in electronics or programming. SSN makes a system easy to maintain, to adapt, and to extend.
- SSN Based Sensor and Actuator Network of the Roboat
Patent "Verfahren zur Navigation und Manövrierung eines vom Wind getriebenen Wasserfahrzeugs" ("System to navigate and to manoeuvre a wind propelled water vehicle")
