| 1. |
- Alhashimi, Anas, 1978-, et al.
(författare)
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Bayesian strategies for calibrating heteroskedastic static sensors with unknown model structures
- 2018
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Ingår i: 2018 European Control Conference (ECC). - Piscataway, NJ : IEEE. - 9783952426982 - 9781538653036 ; , s. 2447-2453
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the problem of calibrating sensors affected by (i) heteroskedastic measurement noise and (ii) a polynomial bias, describing a systematic distortion of the measured quantity. First, a set of increasingly complex statistical models for the measurement process was proposed. Then, for each model the authors design a Bayesian parameters estimation method handling heteroskedasticity and capable to exploit prior information about the model parameters. The Bayesian problem is solved using MCMC methods and reconstructing the unknown parameters posterior in sampled form. The authors then test the proposed techniques on a practically relevant case study, the calibration of Light Detection and Ranging (Lidar) sensor, and evaluate the different proposed procedures using both artificial and field data.
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| 2. |
- Bakarac, Peter, et al.
(författare)
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Explicit MPC Based on Approximate Dynamic Programming
- 2018
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Ingår i: 2018 EUROPEAN CONTROL CONFERENCE (ECC). - 9783952426982 - 9781538653036
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Konferensbidrag (refereegranskat)abstract
- In this paper we show how to synthesize simple explicit MPC controllers based on approximate dynamic programming. Here, a given MPC optimization problem over a finite horizon is solved iteratively as a series of problems of size one. The optimal cost function of each subproblem is approximated by a quadratic function that serves as a cost-to-go function for the subsequent iteration. The approximation is designed in such a way that closed-loop stability and recursive feasibility is maintained. Specifically, we show how to employ sum-of-squares relaxations to enforce that the approximate cost-to-go function is bounded from below and from above for all points of its domain. By resorting to quadratic approximations, the complexity of the resulting explicit MPC controller is considerably reduced both in terms of memory as well as the on-line computations. The procedure is applied to control an inverted pendulum and experimental data are presented to demonstrate viability of such an approach.
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| 3. |
- Fresk, Emil, 1989-, et al.
(författare)
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A generalized Frame Adaptive MPC for the low-level control of UAVs
- 2018
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Ingår i: 2018 European Control Conference (ECC). - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426982 - 9781538653036 ; , s. 1815-1820
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Konferensbidrag (refereegranskat)abstract
- The aim of this article is to establish an adaptiveModel Predictive Control (MPC) scheme for the angular rate and thrust control of a multirotor Unmanned Aerial Vehicle (UAV). The proposed model adaptiveness comes from estimating the movement of the Center of Gravity (CoG) combined withthe thrust constant of the motors, making the system robust to disturbances and fast to adapt to changing parameters, while also taking under consideration the control signal bounds in order to guarantee for no motor stalls, while flying. The linear requirements of the MPC are adhered to by transforming the estimation and control problem into a control signal squared domain, making the system linear. The efficacy of the proposed estimation and control scheme is presented in simulations where worst case scenarios have been considered.
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| 4. |
- Adaldo, Antonio, et al.
(författare)
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Cloud-supported effective coverage of 3D structures
- 2018
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Ingår i: 2018 European Control Conference, ECC 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426982 ; , s. 95-100
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a distributed algorithm for cloud-supported effective coverage of 3D structures with a network of sensing agents. The structure to inspect is abstracted into a set of landmarks, where each landmark represents a point or small area of interest, and incorporates information about position and orientation. The agents navigate the environment following the proposed control algorithm until all landmarks have reached a satisfactory level of coverage. The agents do not communicate with each other directly, but exchange data through a shared cloud repository which is accessed asynchronously and intermittently. We show formally that, under the proposed control architecture, the networked agents complete the coverage mission in finite time. The results are corroborated by simulations in ROS, and experimental evaluation is in progress.
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| 5. |
- Ahlberg, Sofie, et al.
(författare)
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Human in the Loop Least Violating Robot Control Synthesis under Metric Interval Temporal Logic Specifications
- 2018
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Ingår i: 2018 European Control Conference, ECC 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426982 ; , s. 453-458
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Konferensbidrag (refereegranskat)abstract
- Recently, multiple frameworks for control synthesis under temporal logic have been suggested. The frameworks allow a user to give one or a set of robots high level tasks of different properties (e.g. temporal, time limited, individual and cooperative). However, the issue of how to handle tasks, which either seem to be or are infeasible, remains unsolved. In this paper we introduce a human to the loop, using the human's feedback to determine preference towards different types of violations of the tasks. We introduce a metric of violation called hybrid distance. We also suggest a novel framework for synthesizing a least violating controller with respect to the hybrid distance and the human feedback. Simulation result indicate that the suggested framework gives reasonable estimates of the metric, and that the suggested plans correspond to the expected ones.
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| 6. |
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| 7. |
- Charalambous, C. D., et al.
(författare)
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Directed Information Subject to a Fidelity. Applications to Conditionally Gaussian Processes
- 2018
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Ingår i: 2018 European Control Conference, ECC 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426982 ; , s. 3071-3076
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Konferensbidrag (refereegranskat)abstract
- This paper is concerned with the minimization of directed information over conditional distributions that satisfy a fidelity of reconstructing a conditionally Gaussian random process by another process, causally. This information theoretic extremum problem is directly linked, via bounds to the optimal performance theoretically attainable by non-causal, causal and zero-delay codes of data compression. The application example includes the characterization of causal rate distortion function for conditionally Gaussian random processes subject to a meansquare error fidelity.
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| 8. |
- Chong, Michelle, et al.
(författare)
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Estimating the Wigner distribution of linear time-invariant dynamical systems
- 2018
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Ingår i: 2018 European Control Conference, ECC 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426982 ; , s. 1220-1225
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Konferensbidrag (refereegranskat)abstract
- An estimation algorithm for the Wigner distribution (time-frequency representation) of the unmeasured states of a linear time-invariant system is presented. Given that the inputs and outputs are measured, the algorithm involves designing a Luenberger-like observer for each frequency of interest. Under noise-free conditions, we show that the es- timates converge to the true Wigner distribution under a detectability assumption on the time-frequency representation. The estimation algorithm provides estimates which converge to a neighbourhood of the true Wigner distribution where its norm is dependent on the norm of the measurement noise. We also illustrate the efficacy of the estimation algorithm on an academic example and a model of neuron populations.
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| 9. |
- Colombo, Leonardo, et al.
(författare)
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Optimal Control of Left-Invariant Multi-Agent Systems with Asymmetric Formation Constraints
- 2018
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Ingår i: 2018 European Control Conference, ECC 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426982 ; , s. 1728-1733
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Konferensbidrag (refereegranskat)abstract
- In this work we study an optimal control problem for a multi-agent system modeled by an undirected formation graph with nodes describing the kinematics of each agent, given by a left invariant control system on a Lie group. The agents should avoid collision between them in the workspace. Such a task is done by introducing some potential functions into the cost functional for the optimal control problem, corresponding to fictitious forces, induced by the formation constraint among agents, that break the symmetry of the individual agents and the cost functions, and rendering the optimal control problem partially invariant by a Lie group of symmetries. Reduced necessary conditions for the existence of normal extremals are obtained using techniques of variational calculus on manifolds. As an application we study an optimal control problem for multiple unicycles.
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| 10. |
- Csikos, Alfred, et al.
(författare)
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Towards a robust traffic admission control in homogeneous urban vehicular networks under QoS constraints
- 2018
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Ingår i: 2018 European Control Conference (ECC). - 9781538653036 ; , s. 1307-1313
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Konferensbidrag (refereegranskat)abstract
- In this paper, we consider the problem of con- trolling the input flow to a homogeneous urban vehicular network such that certain Quality of Service (QoS) constraints are preserved. In such a network, we model the system with two types of queues: external and internal. External queues represent vehicles waiting to enter the urban vehicular network under control, and the internal queue is used to describe the network’s aggregated behavior based on the Network Fundamental Diagram (NFD). While most of the works assume perfect knowledge of the NFD describing the urban vehicular network, in reality we can only approximate it. On these grounds, by taking a model of the NFD with uncertainties, we propose a robust control design approach in order to gate input flow to a protected urban vehicular network such that travel time Quality of Service (QoS) constraints are preserved within the network. The proposed controller is compared via simulations with controllers assuming perfect knowledge of the NFD and it is shown that it can provide a larger stability region.
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