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247 Autonomous on-comet operations aspects of the ROSETTA mission
Abslracts
545
243 Task.Level Programming with Collision Avoidsaoe for Autonomous Space Robots P. Adolphs, J. Matthleseu, pp 319-324
247 Autonomous On.Comet Operations Aspects of the ROSEITA Mission* K. Schilling, H. Roth, B. Theobold, pp 355-362
The reasons for integratingcollision-avoidingpath planning into a task-level programmable multi-sensor robot system are put forward. The onderlying system ard~ecture sad the specific approaches for environment modelling, task planning and path planning are discussed. Task plaming is performed using a rulebased expert system and a frame represmtation of relevant environment data. Path plannin8 is based on a confq|uration-space approach with a fast new algorithm for obstacle tnmdommtion. Results gained from experimental laboratory work are presented, and show some of the advantages and peoblems of the entire system.
The aim of the ROSETrA-missien is to return pristine material from a comet to Earth. During the phase near and on the comet, spacecraft operations have to be performed autonomously in an unce:tain environment. This paper studies the operational constraints, and analyses an adaptive control concept for the sampling Of cometary materials. The adaptive control algorithm identifies the crucial parameters characterizing the cometary soil and the spacecraft's performance, and adapts the drill's penetration rate and the AOCS cold gas thrusting activities accordingly. This technique has been assessed in computer simulations, and exhibits advantages regarding the reliability of operations and in the efficient use of the limited spacecraft resources. 248 A Development Methodology for Space A & R Control Systems P. Putz, A. Elfving, pp 363-368
244 Moddling sad Control of a HERA Joint R J . Gorter, A. van Swietea, A. Veltman, P.P.J. van den Bosch, pp 325.330 This paper describes the modelling and control of the joints of HERA, a space robot with elastic joints and flexible limbs. On the basis of analytical studies and measurements, a dynamicmodel Of the joints is presented, which cen be used, together with the equations Of motions, to simulate its operations. A derived control design model has been used to investigate the influence Of the joint flexibility and limb flexibility on HERA performance. The performance limitations of decentralized joint control under motor velocity and/or joint position feedback are studied. The performance limitations and the selec~on Of the controller gains can be based on these observations.
245 Devdopmont of an Autonomous Oabourd Control System for Roudezvous and Docking J.M. Pairet, W. Fehse, A. Getzschmsan, pp 331-338 The
Rendezvous
and
Docking
System
Pre-Development
Programme, started in 1989 and concluded in 1992, is an early proof-of-concept of an autonomous RVD enboard system for the various potential European scmarios. On the basis of Hermes and Columbus requirements and baselines, a generic concept of an amonomous onbuard GNC system for RVD, including interaction of human operators, has been defined. The technological items (RV sensors, docking mechanism, GNC processor mock-ups, and onboard software) have been tested, using existing facilities (EPOS, DDTF). The developed concepts are described, the test results are discussed, and recommendations for future development are given.
246 Evaluation of Autonomous GNC Strategies for the Resells Interplouetary Mission C. Champeflor, P. Regnler, J.B. Serrano, J. de Lafontalne, pp 339-353 This paper presents recent resuhs obtained in the ESA study on Autonomous and Advanced Navigation Techniques. New guidance, navigation and control (GNC) cono~ts applicable to the near-comet phases Of the ROSETrA mission have been investigated, and detailed performance results obtained with s complete simulation software tool are described. This paper focuses on the evaluation and performance assessment of GNC concepts applicable to the descent and landing phase, including the attitude and articulation control system concepts, autonomous spacecraft trajectory GNC concepts for the descent phase, and touch-down control concepts. The basic assumptions, the software tool and the simulated models are described, and further recommendations are given.
The European Space Agency's A&R control development methodology (CDM) encompasses guidelines for the design of automation and robotics control systems to accomplish interproject traceability (to account for evolving requirements and technological capabilities for a given system). It calls for a phased analysis and development approach to progress from user requirements to hardware and software implementations. A main focus is on a systematic structuring of the requirements in order to clearly separate functional, application, operational, and implementational influences. Work using the CDM can be very well supported by existing computer-aided software engineering (CASE) tools.
249 Rendezvous and Berthing between Columbus Free Flying Laboratory and Space Station Freedom W. Wighlke, pp 369-374 One of the major goals of the European Columbus project is to perform experiments and processes in a very low microgravity environment. It is therefore the intention to provide a Free Hying Laboratory (Free Flyer) which will be serviced at the Space Station Freedom and by the apaceplane Hermes. For servicing at Freedom, the Free Flyer performs a Rendezvous and Berthing (RvB) operation, which is mainly driven by safety requirements, in particular the demand for collision avoidance. A short interpretafien of the require:nents is given in order to find a strategy that enables the determination of a safe approach and departure trajectory. The RvB scenario is outlined. 250 Synthesis of Robust Multivarlable Controllers for Large Flexible Structure Cher-Hlsag Goh, G. Griibel, pp 375-380 In this paper, the design of robust muldvariable controllers for flexible structures with collocated actuators and sensors is considered. The method exploits the positive realness property of the flexible structure and involves a novel guidance for selecting the weighting matrices for the states and the control inputs, as well as for the covariance matrices of the process and the measurement noise in an LQG approach. Depending on the choice of design parameters, the resulting full-order compensator is guaranteed to be either positive real or strictly positive real. The method is appfied to the DLR flexible test structure to demonstrate its capability.
251 Direct Numerical Design of Reduced Order Controllers from Experimental Data R.D. Irwin, W.G. Frazier, J.R. Mitchell, pp 381-386 The iterative numerical algorithm for designing robust controllers using experimental data models presented here has sevcnd advantages over standard analytical approaches. First, design
545
243 Task.Level Programming with Collision Avoidsaoe for Autonomous Space Robots P. Adolphs, J. Matthleseu, pp 319-324
247 Autonomous On.Comet Operations Aspects of the ROSEITA Mission* K. Schilling, H. Roth, B. Theobold, pp 355-362
The reasons for integratingcollision-avoidingpath planning into a task-level programmable multi-sensor robot system are put forward. The onderlying system ard~ecture sad the specific approaches for environment modelling, task planning and path planning are discussed. Task plaming is performed using a rulebased expert system and a frame represmtation of relevant environment data. Path plannin8 is based on a confq|uration-space approach with a fast new algorithm for obstacle tnmdommtion. Results gained from experimental laboratory work are presented, and show some of the advantages and peoblems of the entire system.
The aim of the ROSETrA-missien is to return pristine material from a comet to Earth. During the phase near and on the comet, spacecraft operations have to be performed autonomously in an unce:tain environment. This paper studies the operational constraints, and analyses an adaptive control concept for the sampling Of cometary materials. The adaptive control algorithm identifies the crucial parameters characterizing the cometary soil and the spacecraft's performance, and adapts the drill's penetration rate and the AOCS cold gas thrusting activities accordingly. This technique has been assessed in computer simulations, and exhibits advantages regarding the reliability of operations and in the efficient use of the limited spacecraft resources. 248 A Development Methodology for Space A & R Control Systems P. Putz, A. Elfving, pp 363-368
244 Moddling sad Control of a HERA Joint R J . Gorter, A. van Swietea, A. Veltman, P.P.J. van den Bosch, pp 325.330 This paper describes the modelling and control of the joints of HERA, a space robot with elastic joints and flexible limbs. On the basis of analytical studies and measurements, a dynamicmodel Of the joints is presented, which cen be used, together with the equations Of motions, to simulate its operations. A derived control design model has been used to investigate the influence Of the joint flexibility and limb flexibility on HERA performance. The performance limitations of decentralized joint control under motor velocity and/or joint position feedback are studied. The performance limitations and the selec~on Of the controller gains can be based on these observations.
245 Devdopmont of an Autonomous Oabourd Control System for Roudezvous and Docking J.M. Pairet, W. Fehse, A. Getzschmsan, pp 331-338 The
Rendezvous
and
Docking
System
Pre-Development
Programme, started in 1989 and concluded in 1992, is an early proof-of-concept of an autonomous RVD enboard system for the various potential European scmarios. On the basis of Hermes and Columbus requirements and baselines, a generic concept of an amonomous onbuard GNC system for RVD, including interaction of human operators, has been defined. The technological items (RV sensors, docking mechanism, GNC processor mock-ups, and onboard software) have been tested, using existing facilities (EPOS, DDTF). The developed concepts are described, the test results are discussed, and recommendations for future development are given.
246 Evaluation of Autonomous GNC Strategies for the Resells Interplouetary Mission C. Champeflor, P. Regnler, J.B. Serrano, J. de Lafontalne, pp 339-353 This paper presents recent resuhs obtained in the ESA study on Autonomous and Advanced Navigation Techniques. New guidance, navigation and control (GNC) cono~ts applicable to the near-comet phases Of the ROSETrA mission have been investigated, and detailed performance results obtained with s complete simulation software tool are described. This paper focuses on the evaluation and performance assessment of GNC concepts applicable to the descent and landing phase, including the attitude and articulation control system concepts, autonomous spacecraft trajectory GNC concepts for the descent phase, and touch-down control concepts. The basic assumptions, the software tool and the simulated models are described, and further recommendations are given.
The European Space Agency's A&R control development methodology (CDM) encompasses guidelines for the design of automation and robotics control systems to accomplish interproject traceability (to account for evolving requirements and technological capabilities for a given system). It calls for a phased analysis and development approach to progress from user requirements to hardware and software implementations. A main focus is on a systematic structuring of the requirements in order to clearly separate functional, application, operational, and implementational influences. Work using the CDM can be very well supported by existing computer-aided software engineering (CASE) tools.
249 Rendezvous and Berthing between Columbus Free Flying Laboratory and Space Station Freedom W. Wighlke, pp 369-374 One of the major goals of the European Columbus project is to perform experiments and processes in a very low microgravity environment. It is therefore the intention to provide a Free Hying Laboratory (Free Flyer) which will be serviced at the Space Station Freedom and by the apaceplane Hermes. For servicing at Freedom, the Free Flyer performs a Rendezvous and Berthing (RvB) operation, which is mainly driven by safety requirements, in particular the demand for collision avoidance. A short interpretafien of the require:nents is given in order to find a strategy that enables the determination of a safe approach and departure trajectory. The RvB scenario is outlined. 250 Synthesis of Robust Multivarlable Controllers for Large Flexible Structure Cher-Hlsag Goh, G. Griibel, pp 375-380 In this paper, the design of robust muldvariable controllers for flexible structures with collocated actuators and sensors is considered. The method exploits the positive realness property of the flexible structure and involves a novel guidance for selecting the weighting matrices for the states and the control inputs, as well as for the covariance matrices of the process and the measurement noise in an LQG approach. Depending on the choice of design parameters, the resulting full-order compensator is guaranteed to be either positive real or strictly positive real. The method is appfied to the DLR flexible test structure to demonstrate its capability.
251 Direct Numerical Design of Reduced Order Controllers from Experimental Data R.D. Irwin, W.G. Frazier, J.R. Mitchell, pp 381-386 The iterative numerical algorithm for designing robust controllers using experimental data models presented here has sevcnd advantages over standard analytical approaches. First, design