Nonlinear vehicle systemdynamics plays an important role in the development and the assessment of active suspension control systems. The current way of designing active suspension control systems mostly uses simplifi...
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Nonlinear vehicle systemdynamics plays an important role in the development and the assessment of active suspension control systems. The current way of designing active suspension control systems mostly uses simplified models, in order to to apply analytical synthesis methods or to achieve low complexity of the controller when using such methods. However, advanced vehicle design require methodologies, that can deal with more complex vehicle models, as a step towards integrated design. Multi-objective control design is such a methodology, that is open to cope with any controller structure and arbitrary kind of models. In this case study the usefulness of this methodology is investigated by designing an actively controlled vehicle suspension with and without preview for the IAVSD benchmark model ILTIS. The full nonlinear model is used for design. The ’nonlinear’ results are compared to the results of a ’linear’ design, based on linearized vehicle models.
A method is addressed for real-time dynamics trajectory optimization of kinematically redundant manipulators. The considered task of trajectory planning is to teach interactively position and orientation of the tool-c...
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A method is addressed for real-time dynamics trajectory optimization of kinematically redundant manipulators. The considered task of trajectory planning is to teach interactively position and orientation of the tool-center point frame, which is fixed in the manipulator hand. Thereby the manipulator has to autonomously preserve explicitly formulated kinematic constraints such as moving obstacle avoidance, singularity avoidance, and box-constraints on joint positions as well as dynamic constraints like box-constraints on joint velocities, accelerations and motor torques. The key idea is to transform the resulting overall motion planning problem into a time series of point-to-point trajectory planning problems, which, in turn, may be formulated as parameter optimization problems, that can be efficiently solved in real-time by the numerical method of sequential quadratic programming. Since the approach does not require an inverse kinematics formulation it is feasible for manipulators with redundant kinematics.
Integrated systems Engineering is essential in design-concept validation. In particular, computer-aided procedures for systemdynamics integration beyond mere functional integration are necessary in order to neither u...
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Integrated systems Engineering is essential in design-concept validation. In particular, computer-aided procedures for systemdynamics integration beyond mere functional integration are necessary in order to neither underestimate nor to overestimate design-safety margins. At hand of the open system-dynamics integration environment ANDECS (ANalysis & DEsign of Controlled systems), we deal with concepts and realized features of a framework for computational experimenting in system-dynamics design and evaluation. This paper is the lead paper to four companion papers which together form a case study on applied multidisciplinary dynamics design experimenting.
作者:
W. KortümDLR
German Aerospace Research Establishment Institute for Robotics and System Dynamics Oberpfaffenhofen 82234 Wessling Germany
The computational analysis of advanced mechatronic vehicles requires complex simulation models as provided by multibody system codes. Moreover, the design of such systems demands multi-objective parameter optimization...
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The computational analysis of advanced mechatronic vehicles requires complex simulation models as provided by multibody system codes. Moreover, the design of such systems demands multi-objective parameter optimization tools. This paper describes the simulation and design environment based on the multibody system code SIM PACK. As a case study the Bombardier ILTIS vehicle is “equipped” with active control loops with and without preview sensors. The multi-objective parameter optimization study using nonlinear and linear analysis methods demonstrates the feasibility of such a complex optimization strategy. Moreover, it indicates the potentials of active supensions with preview sensors. It, last not least, reveals possible misleadings of an optimization based on reduced linear design models.
The performance benefits of an aerodynamically unstable aircraft are obtained at the expense of the necessity of an automatic control system. For reliability requirements controllers without gain scheduling are looked...
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The performance benefits of an aerodynamically unstable aircraft are obtained at the expense of the necessity of an automatic control system. For reliability requirements controllers without gain scheduling are looked for. To achieve this a complex ”robust control” design problem has to be solved. Fuzzy-controllers are claimed to have robustness properties. On the other hand the fuzzy-control methodology can be seen as a systematic way to specify controllers with nonlinear gain surfaces. To properly tune such controllers, computer-aided techniques can be applied provided appropriate models are available such as in more classical design approaches. A fuzzy-controller is developed, which keeps an aerodynamically unstable aircraft stationary for a sufficient long range of time and providing good flying qualities over the entire flight envelope. The results are compared with a completely linear controller design, done earlier.
The robot trajectory optimization features of the ANDECS environment are described. Robot trajectory optimization problems are formulated as multi-objectives parameter optimization problems in search for a good compro...
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The robot trajectory optimization features of the ANDECS environment are described. Robot trajectory optimization problems are formulated as multi-objectives parameter optimization problems in search for a good compromise among conflicting criteria, such as “minimal” time and “minimal” power consumption. For that the robot dynamics is analyzed by time-simulation of a robot model with variable structure, which is generated by the object-oriented modeling language Dymola.
In many robotics applications, e.g. telerobotics under long time delay, building a geometric world model from multisensory data is a crucial requirement. Using a sensor-in-hand configuration to generate a model refere...
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In many robotics applications, e.g. telerobotics under long time delay, building a geometric world model from multisensory data is a crucial requirement. Using a sensor-in-hand configuration to generate a model referenced to the robot base, imposes specific problems. Moving the sensor frame on an arbitrary path over and around an unknown object generates a completely unordered 'data cloud'. A surface reconstruction algorithm, which is based on Kohonen's self-organizing feature maps is used to process this data cloud and to generate a useful surface description. This surface can be used for object recognition and pose estimation using algorithms which were developed in the field of range image understanding.
For a low speed Maglev system of the single stage suspension type a control design study is described where a ’classical’ dynamic compensator control structure is compared with a ’modern’ LQG control structure. To...
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For a low speed Maglev system of the single stage suspension type a control design study is described where a ’classical’ dynamic compensator control structure is compared with a ’modern’ LQG control structure. To properly tune the free parameters in the respective controller synthesis procedures the ANDECS-MATLAB design environment is used. The multi-objective design approach of ANDECS allows to simultaneously satisfy the suspension requirements corresponding to both random and deterministic inputs.
Artificial potential fields have enjoyed growing popularity for path planning and collision avoidance both of robot manipulators and mobile robots. Although many artificial potential fields have been proposed. Few wor...
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Artificial potential fields have enjoyed growing popularity for path planning and collision avoidance both of robot manipulators and mobile robots. Although many artificial potential fields have been proposed. Few works discuss suitable control for tracking the gradient of an artificial potential field. This deficit is surprising since good tracking control is vital for successful implementation of the artificial potential field method. This paper extends previous results of a sliding mode control strategy for fully actuated holonomic robots to gradient tracking of non-holonomic mobile robots.
This paper continues demonstration of the benefits of parallel multibody simulation. In Part I implicit integration schemes combined with a modified inverse dynamic formulation were proposed for parallel multibody sim...
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This paper continues demonstration of the benefits of parallel multibody simulation. In Part I implicit integration schemes combined with a modified inverse dynamic formulation were proposed for parallel multibody simulation. In Part II the modified inverse dynamics algorithm and computation of the integrator's Jacobian are split up into independent work packages for parallelization on medium-and coarse-grain levels, respectively. The farming concept, which organizes the flow of work and result packages through a network of processors, is presented. Transputers are used to build a distributed memory multiprocessor system, where both the medium- and coarse-grain approaches are implemented, resulting in the PARSIM-package for parallel multibody dynamics. The simulation of an off-road vehicle and a multibody model for a cable demonstrate the considerable savings in simulation times achieved by the new software package.
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