S. Hirche

Technische Universität München, München, Bavaria, Germany

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Publications (60)27.59 Total impact

  • M.H. Mamduhi · D. Tolic · S. Hirche ·
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    ABSTRACT: This paper modifies a recently proposed event-based probabilistic medium access for multi-loop Networked Control Systems (NCSs) over a shared communication channel subject to limited capacity and uncertainties and study its robustness. The novel design combines deterministic and probabilistic attributes to efficiently allocate the channel access among the control loops in the presence of network-induced phenomena such as packet dropouts and scheduling with delayed information update. Since the scheduler receives error information from a number of systems simultaneously, this sheer amount of information cannot always be processed in timely manner, which in turn gives rise to delays. Given the local error thresholds, the subsystems with error values lower than their corresponding thresholds are deterministically excluded from the medium access competition in favor of those with larger errors. In case of resource scarcity, the scheduler probabilistically allocates the channel to those that exceed the local thresholds according to an error-dependent priority measure. We show stochastic stability of such NCSs in terms of '-ergodicity of the network-induced error, which is modeled as a Markov chain. Numerical results validate our stability results in the presence of packet dropouts and delayed data update.
    Proceedings of the American Control Conference 07/2015; 2015:4695-4701. DOI:10.1109/ACC.2015.7172069
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    ABSTRACT: This paper discusses an online dynamic motion generation scheme for nonprehensile object manipulation by using a set of predefined motions and a trajectory deformation algorithm capable of incorporating positional and velocity boundary constraints. By creating optimal trajectories offline and deforming them online, computational complexity during execution is reduced considerably. As tight convex hulls of the deformed trajectories can be found, possible obstacles or workspace boundaries can be circumnavigated precisely without collision. The approach is verified through experiments on an inclined planar air-table for volleyball scenario using two 3-DoF robots.
    Proceedings - IEEE International Conference on Robotics and Automation 06/2015; 2015:2481-2487. DOI:10.1109/ICRA.2015.7139531
  • F. Deroo · S. Hirche · B.D.O. Anderson ·
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    ABSTRACT: In this paper we analyze the propagation of input signals in a large-scale network of dynamical systems. Using vector Lyapunov functions, the individual multidimensional subsystems are first reduced to an approximating scalar representation in the form of the evolution of their weighted norm. The norm simultaneously qualifies as a local Lyapunov function for the isolated subsystem. Employing properties of M-matrices, we then derive linear system dynamics which provide an upper bound for the evolution of the original system, and use them to investigate the decay between hops from subsystem to subsystem of the steady state magnitude. Two input signals are considered: Constant input, and a sinusoidal input. The results are demonstrated using numerical simulations.
  • D. Tolic · S. Hirche ·
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    ABSTRACT: This paper proposes a methodology for computing Maximally Allowable Transfer Intervals (MATIs) that provably stabilize nonlinear Networked Control Systems (NCSs) in the presence of disturbances and signal delays. Accordingly, given a desired level of system performance (in terms of p-gains), quantitative MATI vs. delay trade-offs are obtained. By combining impulsive delayed system modeling with Lyapunov-Razumikhin type of arguments, we are able to consider even the so-called large delays. Namely, the computed MATIs can be smaller than delays existent in NCSs. In addition, our stability results are provided for the class of Uniformly Globally Exponentially Stable (UGES) scheduling protocols. The well-known Round Robin (RR) and Transmit-Once-Discard (TOD) protocols are examples of UGES protocols. Apart from the inclusion of large delays, another salient feature of our methodology is the consideration of corrupted data. To that end, we propose the notion of p-stability with bias. Furthermore, the Zeno-free property of our methodology is demonstrated. Finally, a comparison with the state-of-the-art work is provided utilizing the benchmark problem of batch reactor.
    Proceedings of the IEEE Conference on Decision and Control 02/2015; 2015:1203-1208. DOI:10.1109/CDC.2014.7039545
  • M.H. Mamduhi · D. Tolic · A. Molin · S. Hirche ·
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    ABSTRACT: In this paper, we study event-triggered data scheduling for stochastic multi-loop control systems communicating over a shared network with communication uncertainties. We introduce a novel dynamic scheduling scheme which allocates the channel access according to an error-dependent policy. The proposed scheduler deterministically excludes subsystems with lower error values from the medium access competition in favor of those with larger errors. Subsequently, the scheduler probabilistically allocates the communication resource to the eligible entities. We model the overall network-induced error as a homogeneous Markov chain and show its boundedness in expectation over a multi time-step horizon. In addition, analytical upper bound for the associated average cost is derived. Furthermore, we show that our proposed policy is robust against packet dropouts. Numerical results demonstrate a significant performance improvement in terms of error level in comparison with periodic and random scheduling policies.
    Proceedings of the IEEE Conference on Decision and Control 02/2015; 2015:2776-2782. DOI:10.1109/CDC.2014.7039815
  • M. Kimmel · S. Hirche ·
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    ABSTRACT: In many control applications, state and/or output constraints need to be satisfied. For that purpose, artificial limits are imposed using a specially designed control law. Among other methods, invariance control has proven valuable for addressing the problem of state and output constraints in nonlinear control systems. However, invariance controlled systems often exhibit undesirable chattering behavior in particular in digital implementation. In this work, we propose a novel invariance-based control approach, which significantly reduces chattering. We give a condition for stability and restrictions on the admissible constraint configuration. The approach and the results are illustrated in simulations.
    IEEE 53rd Annual Conference on Decision and Control (CDC); 12/2014
  • Source
    Adam Molin · Sandra Hirche ·
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    ABSTRACT: The advent of networked control systems urges the digital control design to incorporate communication constraints efficiently. In order to accommodate this requirement, this article studies the joint design of controller and event-trigger for linear stochastic systems in the presence of a resource-limited communication channel which exhibits packet dropouts and time-delay. The event-trigger situated at the sensor decides at every sampling instance, whether to send information over the communication channel to the controller. The design approach is formulated as a stochastic average-cost optimization problem, where the communication constraints are reflected as an additional cost penalty of the average transmission rate. Different conditions on the communication model are given where the joint optimal design can be split into a separate control and event-trigger design. Based on these results, two suboptimal design approaches are developed. By using drift criteria, stability guarantees of the closed-loop system for both approaches are derived in terms of bounded moment stability. Numerical simulations illustrate the efficacy of the event-triggered approach compared with optimal time-triggered controllers.
    ZAMM Journal of applied mathematics and mechanics: Zeitschrift für angewandte Mathematik und Mechanik 04/2014; 94(4). DOI:10.1002/zamm.201100139 · 1.16 Impact Factor
  • B. Lohmann · F. Deroo · S. Hirche · J. Lunze · M. Meinel · P. Philipp · M. Ulbrich ·
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    ABSTRACT: For interconnected systems, the state estimation and control algorithms associated with the subsystems can communicate over the network to improve their performance. This chapter describes methods for structuring the overall control system including the communication network and shows how to use the communicated information for estimation and control if the network induces transmission delays and packet loss.
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    ABSTRACT: In event-based control, the feedback loop is closed only if an event indicates that the control error exceeds a tolerable bound and triggers a data transmission from the sensors to the controllers and the actuators. Hence, event-based control is an important method for reducing the communication load of a digital network. This chapter explains the main ideas of event-based control and proposes new loop structures and design methods.
  • Source
    Jose Ramon Medina · Martin Lawitzky · Adam Molin · Sandra Hirche ·
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    ABSTRACT: It is well-known that physical robotic assistance to humans is significantly enhanced by including human behavior anticipation into robot planning and control. The challenge arises when the human goal/plan is uncertain or unknown to the robot. In this paper we propose a novel control scheme which dynamically selects between a model-based and a model-free strategy depending on the level of disagreement between the human and the robot. The disagreement is measured in terms of the interaction force. A task specific model-based controller is selected when the human's motion intention coincides with the robot's goal. A model-free control scheme based on the human force as motion prediction source is selected in case of disagreement and when the human goal/plan is unknown. The benefits of this approach are demonstrated in a human user study on human-robot cooperative object transport through a 2D maze in virtual reality.
    Robotics and Automation (ICRA), 2013 IEEE International Conference on; 05/2013
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    Jose Ramon Medina · Dominik Sieber · Sandra Hirche ·
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    ABSTRACT: Manipulation tasks are a great challenge for robots due to the uncertainty arising from unstructured environments. In this paper we propose a novel control scheme for contact tasks based on risk-sensitive optimal feedback control. It provides a systematic approach to adjust the trade-off between motion and force control under uncertainty. Following a previously acquired task model, the proposed approach provides both a variable stiffness solution and a motion reference adaptation. This control scheme achieves increased adaptability under previously unseen environmental variability. An implementation on a robotic manipulator validates the applicability and adaptability of the proposed control approach in two different manipulation tasks.
    Robotics and Automation (ICRA), 2013 IEEE International Conference on; 05/2013
  • Tamara Lorenz · Alexander Mortl · Sandra Hirche ·
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    ABSTRACT: Interpersonal movement synchronization is a phenomenon that does not only increase the predictability of movements; it also increases rapport among people. In this line, synchronization might enhance human-robot interaction. An experiment is presented which explores to what extend a human synchronizes own movements to a non-adaptive robot during a repetitive tapping task. It is shown that the human does not take over the complete effort of movement adaptation to reach synchronization, which indicates the need for adaptive robots.
    Human-Robot Interaction (HRI), 2013 8th ACM/IEEE International Conference on; 03/2013
  • Haiyan Wu · Lei Lou · Chih-Chung Chen · Sandra Hirche · Kolja Kuhnlenz ·
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    ABSTRACT: The performance of vision-based control systems, in particular, of highly dynamic vision-based motion control systems, is often limited by the low sampling rate of the visual feedback caused by the long image processing time. In order to overcome this problem, the networked visual servo control (NVSC), which integrates networked computational resources for cloud image processing, is considered in this paper. The main contributions of this paper are the following: 1) a real-time transport protocol for transmitting large-volume image data on a cloud-computing platform, which enables high-sampling-rate visual feedback; 2) a stabilizing control law for the NVSC system with time-varying feedback time delay; and 3) a sending rate scheduling strategy aiming at reducing the communication network load. The performance of the NVSC system with sending rate scheduling is validated in an object-tracking scenario on a 14-DOF dual-arm robot. Experimental results show the superior performance of our approach. In particular, the communication network load is substantially reduced by means of the scheduling strategy without performance degradation.
    IEEE Transactions on Industrial Electronics 02/2013; 60(2):554-566. DOI:10.1109/TIE.2012.2186775 · 6.50 Impact Factor
  • Source
    Adam Molin · Sandra Hirche ·
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    ABSTRACT: Digital control design is commonly constrained to time-triggered control systems with periodic sampling. The emergence of more and more complex and distributed systems urges the development of advanced triggering schemes that utilize communication, computation, and energy resources more efficiently. This technical note addresses the question whether certainty equivalence is optimal for an event-triggered control system with resource constraints. The problem setting is an extension of the stochastic linear quadratic system framework, where the joint design of the control law and the event-triggering law minimizing a common objective is considered. Three differing variants are studied that reflect the resource constraints: a penalty term to acquire the resource, a limitation on the number of resource acquisitions, and a constraint on the average number of resource acquisitions. By reformulating the underlying optimization problem, a characterization of the optimal control law is possible. This characterization shows that the certainty equivalence controller is optimal for all three optimization problems.
    IEEE Transactions on Automatic Control 02/2013; 58(2):470-474. DOI:10.1109/TAC.2012.2206719 · 2.78 Impact Factor
  • M. Lawitzky · M. Kimmel · P. Ritzer · S. Hirche ·
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    ABSTRACT: Trajectory generation for active physical assistance to humans in cooperative haptic tasks gains increasing interest in recent literature. Planning-based approaches represent one class of trajectory synthesis methods for active robotic partners. To overcome the limitations of kinematic planning algorithms in dynamic tasks, we propose a three-step approach to the synthesis of trajectories under the principle of least action. This is motivated by neuroscientific findings on human effort minimization in motor tasks. A trajectory is generated by optimized sequencing of optimal motion primitives. The benefits of the proposed method for physical human-robot cooperation are demonstrated in human user studies in a 2D cooperative transport task in a virtual maze.
    Robotics and Automation (ICRA), 2013 IEEE International Conference on; 01/2013
  • Huang Huang · Changbin Yu · Azwirman Gusrialdi · Sandra Hirche ·
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    ABSTRACT: This paper considers the optimal local leader selection for a leader-first follower minimally persistent formation system. The objective is to maximize the local convergence rate of the followers to the unique equilibrium under small perturbations. Except for the leader and the first follower, every other agent in the system follows exactly two agents called the local leaders and is responsible for maintaining a pair of desired distances from two local leaders. The control algorithm is the linearized form of the decentralized nonlinear control law proposed in our previous work. When the agents are distributed over a rectangular area, the selection of the optimal local leader for each follower is discussed, and it is discovered that the boundary optimality rule applies. The general case when agents distributed over an arbitrary convex domain is further considered based on the matrix perturbation theory. Information of agents in its sensing range is enough for the agent to pick up its optimal local leaders, which allows a distributed implementation of the proposed algorithm.
    American Control Conference (ACC), 2012; 06/2012
  • A. Gusrialdi · S. Hirche ·
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    ABSTRACT: Communication networks provide a larger flexibility for the control design of large-scale interconnected systems by allowing the information exchange between the local controllers of the subsystems. This paper presents explicit solutions on communication topology design for interconnected systems with certain class of physical interconnection topology, namely ring, star and line structure based on eigenvalue sensitivity analysis. First, the explicit solutions for the case of scalar subsystems with identical local dynamics and a single communication link are derived. Furthermore, it is investigated how the heterogeneity of the subsystem local dynamics affects the communication topology. Finally it is discussed how the results can be extended to the case of non-scalar subsystems and multiple communication links.
    American Control Conference (ACC), 2012; 06/2012
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    ABSTRACT: In this video we present a teleoperation system which is capable of solving complex tasks in human-sized wide area environments. The system consists of two mobile teleoperators controlled by two operators, and offers haptic, visual, and auditory feedback. The task examined here, consists of repairing a robot by removing a computer and replacing a defective hard-drive. To cope with the complexity of such a task, we go beyond classical teleoperation by integrating several advanced software algorithms into the system.
    Proceedings of the IEEE International Conference on Robotics and Automation (ICRA); 05/2012
  • P Basili · M Huber · O Kourakos · T Lorenz · T Brandt · S Hirche · S Glasauer ·
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    ABSTRACT: The ability to infer intentions and predict actions enables coordinating of one's own actions with those of another human and allows smooth and intuitive interaction. The aim to achieve equally effective human-robot interactions is a crucial aspect of current robotic studies. Thus, we assume that studying human-human interaction provides valuable insights allowing to implement mutual intention recognition and action prediction in robotic systems. A common scenario of interaction, be it in everyday life or in an industrial setting, is that two or more agents share the same workspace and perform tasks without interference. If humans are involved, the robots should act sufficiently predictable to enable the human to attribute goals and predict motion trajectories. In the present work, we first analyzed how well a human recognizes the goal of another person entering the room, and whether this ability is deteriorated by concealing gaze direction of the other person. In a second setup, the same experiment was repeated by replacing the approaching person with a wheeled robot. On average, the distance at which subjects predicted the goal of the approaching agent was approx. 4 m and depended on subject and goal position, but not on the type of agent. However, goal attribution showed a considerable proportion of errors for the robot (19%), much less for a human with hidden gaze direction (6%), and almost none for a human with visible gaze (1%). Thus, our subjects apparently decided on the goal of the approaching agent without taking into account the reliability of directional cues, thus resulting in more errors. In a human-robot setting, such wrong predictions about robotic behavior may easily lead to dangerous situations. For smooth and safe interaction, it is therefore important to ameliorate the predictability of robotic actions.
    RO-MAN, 2012 IEEE; 01/2012
  • A. Molin · S. Hirche ·
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    ABSTRACT: Under many circumstances event-triggered control outperforms time-triggered control schemes when resources such as communication, computation, or energy are sparse. This paper investigates another benefit of event-triggered control concerning the ability of adaptation. The system under consideration comprises multiple heterogeneous control loops that are closed over a shared communication network. Each subsystem is modelled as a discrete-time stochastic linear system. The design problem is formulated as an average cost Markov decision process (MDP) with unknown global system parameters that are to be estimated during execution. Techniques from distributed optimization and adaptive MDPs are used to develop distributed self-regulating event-triggers that adjust their transmission rate to meet a global resource constraint. Numerical simulations show the effectiveness of the approach and illustrate the convergence properties.
    Decision and Control (CDC), 2012 IEEE 51st Annual Conference on; 01/2012

Publication Stats

834 Citations
27.59 Total Impact Points


  • 2005-2014
    • Technische Universität München
      • • Department of Information-oriented Control
      • • Institute of Automatic Control Engineering (LSR)
      München, Bavaria, Germany
  • 2006-2011
    • Tokyo Institute of Technology
      • Department of Department of Mechanical and Control Engineering
      Edo, Tōkyō, Japan
  • 2003
    • Technische Universität Berlin
      • School IV Electrical Engineering and Computer Science
      Berlin, Land Berlin, Germany