| 1. |
|
|
| 2. |
- Henningsson, Maria, et al.
(författare)
-
LQG Control for Minimization of Emissions in a Diesel Engine
- 2008
-
Ingår i: 2008 IEEE International Conference on Control Applications, Vol1 and 2. - 1085-1992. - 9781424422227 ; , s. 303-308
-
Konferensbidrag (refereegranskat)abstract
- The problem of minimizing emissions of NO. and soot in a diesel engine using fuel injection timings and exhaust gas recirculation (EGR) valve position in a low-pressure EGR system as control variables is addressed. Two feedback variables are computed from in-cylinder pressure sensor data, the crank angle degree of 50 % fuel burnt, and the ignition delay. Empirical maps of NO, and soot according to the feedback variables form the basis of a quadratic cost function in the feedback variables which is minimized by LQG control. For a multi-cylinder engine, the number of control variables will be less than the number of output variables to be controlled, and the consequences of this setup for the LQG controller is addressed. Experimental results verify the performance of the controller at a fixed operating point of a six-cylinder heavy-duty engine.
|
|
| 3. |
- Templin, Peter, 1969
(författare)
-
Simultaneous estimation of driveline dynamics and backlash size for control design
- 2008
-
Ingår i: 17th IEEE International Conference on Control Applications, CCA; San Antonio, TX; United States; 3 September 2008 through 5 September 2008. - 1085-1992. - 9781424422227 ; , s. 13-18
-
Konferensbidrag (refereegranskat)abstract
- The Shunt and shuffle-phenomenon at rapid torque transients in a vehicle driveline greatly influences the drivability. A dynamic model that can describe both the traversing of the backlash and the following poorly damped oscillations is proposed. It is experimentally shown to have good predictive capability which is important for control design. The model includes backlash to avoid underestimating the oscillation amplitude after rapid large accelerator pedal movements (ldquotip-in/outrdquo). The parameter estimation results are obtained using only the existing engine torque signal and engine and vehicle speed measurements.
|
|
| 4. |
- Berntorp, Karl, et al.
(författare)
-
Mobile Manipulation with a Kinematically Redundant Manipulator for a Pick-and-Place Scenario
- 2012
-
Ingår i: [Host publication title missing]. - 1085-1992. ; , s. 1596-1602
-
Konferensbidrag (refereegranskat)abstract
- Mobile robots and robotic manipulators have traditionally been used separately performing different types of tasks. For example, industrial robots have typically been programmed to follow trajectories using position sensors. If combining the two types of robots and adding sensors new possibilities emerge. This enables new applications, but it also raises the question of how to combine the sensors and the added kinematic complexity. An omni-directional mobile robot together with a new type of kinematically redundant manipulator for future use as a service robot for grocery stores is proposed. The scenario is that of distributing groceries on refilling shelves, and a constraint- based task specification methodology to incorporate sensors and geometric uncertainties into the task is employed. Sensor fusion is used to estimate the pose of the mobile base online. Force sensors are utilized to resolve remaining uncertainties. The approach is verified with experiments.
|
|
| 5. |
- Filieri, Antonio, et al.
(författare)
-
Discrete-time dynamic modeling for software and services composition as an extension of the Markov chain approach
- 2012
-
Ingår i: IEEE International Conference on Control Applications (CCA), 2012. - 1085-1992. - 9781467345033 ; , s. 557-562
-
Konferensbidrag (refereegranskat)abstract
- Discrete Time Markov Chains (DTMCs) and Con- tinuous Time Markov Chains (CTMCs) are often used to model various types of phenomena, such as, for example, the behavior of software products. In that case, Markov chains are widely used to describe possible time-varying behavior of “self-adaptive” software systems, where the transition from one state to another represents alternative choices at the software code level, taken according to a certain probability distribution. From a control-theoretical standpoint, some of these probabil- ities can be interpreted as control signals and others can just be observed. However, the translation between a DTMC or CTMC model and a corresponding first principle model, that can be used to design a control system is not immediate. This paper investigates a possible solution for translating a CTMC model into a dynamic system, with focus on the control of computing systems components. Notice that DTMC models can be translated as well, providing additional information.
|
|
| 6. |
- Ghazaei, Mahdi, et al.
(författare)
-
An Analytic Solution to Fixed-Time Point-to-Point Trajectory Planning
- 2015
-
Ingår i: Proc. 2015 IEEE Conference on Control and Applications (CCA 2015). - 1085-1992. - 9781479977871 ; , s. 11-306
-
Konferensbidrag (refereegranskat)abstract
- We derive an analytic solution to the problem of fixed-time trajectory generation with a quadratic cost function under velocity and acceleration constraints. This problem has a wide range of applications within motion planning. The advantage of the analytic solution compared to numerical optimization of the discretized problem is the unlimited resolution of the solution and the efficiency of the calculation, allowing sensor-based replanning and on-line trajectory generation.
|
|
| 7. |
- Haugwitz, Staffan, et al.
(författare)
-
Analysis and design of startup control of a chemical plate reactor with uncertainties; a hybrid approach
- 2007
-
Ingår i: IEEE International Conference on Control Applications, 2007. CCA 2007.. - 1085-1992. ; , s. 1209-1214
-
Konferensbidrag (refereegranskat)abstract
- The startup of a chemical plate reactor is investigated. A hybrid startup control scheme is presented and a discussion is made on how hybrid transition points could be chosen to allow safe startup despite actuator limitations, process nonlinearities and model uncertainties. The event-driven startup improves the robustness to uncertainties and disturbances, since each part of the startup is associated with a feedback in the form of a transition condition that needs to be satisfied to allow the startup to continue.
|
|
| 8. |
- Khong, Sei Zhen
(författare)
-
Non-Model Based Finite-Horizon Sampled-Data Optimal Control Via Global Extremum Seeking
- 2014
-
Ingår i: [Host publication title missing]. - 1085-1992. ; , s. 1400-1405
-
Konferensbidrag (refereegranskat)abstract
- A non-model based approach to finite-horizon optimal sampled-data control of continuous-time nonlinear systems subject to input saturation constraints is proposed. The approach adapts the global optimisation method DIRECT to computing a periodically piecewise constant system input which minimises a possibly non-quadratic cost involving the system state and input. In the case where several similar plants are available, multi-agent extremum seeking control is considered for the purpose of expediting the search for an optimal control law within a tolerable margin of errors. An example based on pendulum dynamics illustrates the results.
|
|
| 9. |
- Leva, Alberto, et al.
(författare)
-
Performance analysis of operating systems schedulers realised as discrete-time controllers
- 2012
-
Ingår i: IEEE International Conference on Control Applications (CCA), 2012. - 1085-1992. - 9781467345033 ; , s. 745-750
-
Konferensbidrag (refereegranskat)abstract
- Recent papers have proposed to design scheduling algorithms entirely as discrete-time controllers, i.e., to refrain from preserving the already installed scheduler, and replace it completely. At the cost of some system re-design impact, this new approach has been proved to yield significant advantages in terms of code size and simplicity, and above all to open the way to a system-theoretical analysis, thereby permitting to prove relevant properties in a rigorous manner. This manuscript presents some refinements and improvements of an already conceived control structure, allowing for more flexible task management and better comprehension on the part of the system administrator. A standard benchmark is used to support the necessary performance analysis.
|
|
| 10. |
- Pfeiffer, Roland, et al.
(författare)
-
System Identification and LQG Control of Variable-Compression HCCI Engine Dynamics
- 2004
-
Ingår i: Proceedings of the 2004 IEEE International Conference on Control Applications.. - 1085-1992. - 0780386337 ; 2, s. 1442-1447
-
Konferensbidrag (refereegranskat)abstract
- The Homogenous Charge Compression Ignition (HCCI) combustion engine has potential to replace the spark ignition and compression ignition engines of today. One of the main problems in making the engine commercially attractive is the lack of direct means of controlling the ignition phasing. In this paper, we investigate the potential of inlet air temperature as a means to ignition actuation. This article describes a method for system identification of the HCCI process, and development of an effective LQG regulator for the combustion process, Matlab and Simulink being used in computations and simulations.
|
|
| 11. |
- Sun, Da, 1989-, et al.
(författare)
-
Enhancing flexibility of the dual-master-dual-slave multilateral teleoperation system
- 2015
-
Ingår i: Proceedings of the IEEE Conference on Control Applications. - : IEEE Geoscience and Remote Sensing Society. - 1085-1992. ; , s. 300-305
-
Tidskriftsartikel (refereegranskat)abstract
- A flexible dual-master-dual-slave teleoperation system is proposed. On the master side, a new control law with a variable dominance factor is proposed to offer the system high flexibility and ease of training. A new wave-based Time Domain Passivity Approach (TDPA) is deployed to guarantee the channel passivity and high transparency in the presence of random time delays. The proposed algorithm is validated by applying it to a multilateral teleoperation platform consisting of four 3-DOF haptic devices configured as two masters and two slaves. The results demonstrate the feasibility of the proposed system in different complex tasks and its superior performance compared to previous work.
|
|
| 12. |
- Sörnmo, Olof, et al.
(författare)
-
Force Controlled Knife-Grinding with Industrial Robot
- 2012
-
Ingår i: 2012 IEEE Multi-Conference on Systems and Control. - 1085-1992. ; , s. 1356-1361
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates the application of sharpening knives using a force controlled industrial robot, for an arbitrary knife shape and orientation. The problem is divided into different parts: calibration of the knife by identifying its unknown orientation, identification of the knife blade contour and estimation of its position in the robot frame through force control, and grinding of the knife, following the path defined by the earlier identified shape, while applying the desired contact force to the revolving grinding wheels. The experimental results show that the knives can be sharpened satisfactorily. An industrial application has also been developed and tested, and it has produced a sharpening quality equal or greater to that achieved manually.
|
|
| 13. |
- Templin, Peter, 1969, et al.
(författare)
-
An LQR torque compensator for driveline oscillation damping
- 2009
-
Ingår i: 2009 IEEE International Conference on Control Applications, CCA '09; Saint Petersburg; Russian Federation; 8 July 2009 through 10 July 2009. - 1085-1992. - 9781424446018 ; , s. 352-356
-
Konferensbidrag (refereegranskat)abstract
- This paper derives an LQR anti-jerk controller for an automotive driveline. The time derivative of the drive shaft torque, which is closely related to the vehicle jerk, is used as a virtual system output and regulated to zero. Thereby the controller does not need a reference model for generation of reference trajectories for the control law evaluation. The controller acts as a torque compensator for the driver's torque demand which the controller output asymptotically follows. The properties of the controller are discussed and the behavior is illustrated by simulation examples.
|
|
| 14. |
- Widd, Anders, et al.
(författare)
-
Experimental Evaluation of Predictive Combustion Phasing Control in an HCCI Engine using Fast Thermal Management and VVA
- 2009
-
Ingår i: Proceedings of the IEEE International Conference on Control Applications. - 1085-1992. - 9781424446018 ; , s. 334-339
-
Konferensbidrag (refereegranskat)abstract
- This paper presents experimental results on model predictive control of the combustion phasing in a Homogeneous Charge Compression Ignition (HCCI) engine. The controllers were based on linearizations of a previously presented physical model of HCCI including cylinder wall temperature dynamics. The control signals were the inlet air temperature and the inlet valve closing. A system for fast thermal management was installed and controlled using mid-ranging control. The resulting control performance was experimentally evaluated in terms of response time and steady-state output variance. For a given operating point, a comparable decrease in steady-state output variance was obtained either by introducing a disturban ce model or by changing linearization point. The robustness towards disturbances was investigated as well as the effects of varying the prediction and control horizons.
|
|
| 15. |
- Ulen, Barbro, et al.
(författare)
-
Lagged response of nutrient leaching to reduced surpluses at the field and catchment scale
- 2015
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 29, s. 3020-3037
-
Tidskriftsartikel (refereegranskat)abstract
- Lag times in reduced nutrient leaching after improved agricultural practices must be assessed to inform management decisions and evaluate their cost-effectiveness. This study estimated the leaching of phosphorus (P) and nitrogen (N) at two scales, a 33.8-ha nested field (data from 1973 to 2011) and an 820-ha agricultural catchment (data from 1992 to 2010). Field management was evaluated along with long-term nutrient trends. Estimates including and excluding nutrient concentrations in the stream under dry catchment conditions (mean 2.5monthsyear(-1)) revealed that wastewater contributed 10% of the total P (TP) catchment leaching, mostly in dissolved reactive (DRP) form. More recent flow-proportional sampling at the two scales demonstrated 45% higher particulate P leaching from the field than with discrete water sampling, whereas a past discrete sampling strategy may have overestimated DRP contributions to the stream. The accumulated field P balance was increasingly negative after 1987, whereas crop yields increased. From 1998, the measured accumulated TP leaching from the field was lower than the mean accumulated leaching, considering the estimated downward trend (-10%) over the 38-year study period (p<0.05). The average total N (TN) field leaching of 28kgha(-1)year(-1) (1973-2011) was 10% higher than the catchment leaching (1992-2010). The rates and timing of fields N and P fertilization became better adapted to crop requirements over time, and thereafter, a 14% reduction in TN leaching was estimated. No significant trends were estimated for catchment leaching for either TP or TN over the 18-year period, demonstrating an extended lag period for reduced nutrient leaching and the need for long-term monitoring of the effects of pollution mitigation. Copyright (c) 2014 John Wiley & Sons, Ltd.Highlights Time lag in P and N leaching responses to reduce nutrient surpluses Close relationship with N export at nested scale Scale effects in Q indices and PP transport Point sources of pollution prolonging the time lag for DRP leaching mitigation
|
|
| 16. |
- Nyberg, Lars, et al.
(författare)
-
Water transit times and flow paths from two line injections of 3H and 36Cl in a microcatchment at Gårdsjön, Sweden
- 1999
-
Ingår i: Hydrological Processes. - 0885-6087 .- 1099-1085. ; 13:11, s. 1557-1575
-
Tidskriftsartikel (refereegranskat)abstract
- To investigate groundwater transit times and flow paths in shallow till soil, within an acidification study at Gardsjon, Sweden, two line injections of Cl-36 and H-3 Were made in groundwater during 1992. The first injection in January, when the two tracers were injected at the same depth, gave tracer transit times from injection line to outlet of some hours due to a runoff event on the first day. The subsequent recession period left a considerable amount of tracer in the unsaturated zone, which had transit times that ranged from weeks to months. Tracer recovery at the outlet was 78% for H-3 and 47% for Cl-36. Cl retention was indicated. The second injection in November, when H-3 was injected at 30 cm depth and 36C1 at 60 cm depth, gave recoveries of 96% for H-3 and 83% for Cl-36. Apart from an advective flow-dependent tracer transport, very fast tracer pulses occurred. The velocities for those pulses were of the order of tens of metres per hour. Highest tracer concentrations were observed in the superficial soil layers, which suggest that these layers were the dominant flow paths.
|
|
| 17. |
- Seibert, J., 1968-, et al.
(författare)
-
Water storage in a till catchment. I : Distributed modelling and relationship to runoff
- 2011
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 25:25, s. 3937-3949
-
Tidskriftsartikel (refereegranskat)abstract
- Although water storage is an important variable to understand the hydrological functioning of a catchment, it is challenging to estimate the total water storage in a catchment. Catchment water storage can be estimated on the basis of water balance, but this approach is prone to errors in the different water balance terms. Here, an approach is presented to estimate the daily dynamics of catchment-wide soil water and groundwater storage on the basis of groundwater-level observations, soil properties and an assumption of hydrological equilibrium above the water table. This approach was applied to a 6300-m2 till catchment in Southwest Sweden. The predicted mean catchment water storage between April 1991 and June 1992 was 210mm and ranged from 190 to 260mm. The estimated water storage followed runoff rates closely especially during recession periods. On average, 79% of the water storage was held in the unsaturated zone, and the remaining 21% was groundwater, but this proportion varied strongly with runoff and total storage. During dry conditions, unsaturated storage accounted for at maximum 95% of the water storage; during wet conditions, this number dropped to 40%. Copyright (c) 2011 John Wiley & Sons, Ltd.
|
|
| 18. |
- Beven, Keith J., et al.
(författare)
-
GLUE : 20 years on
- 2014
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 28:24, s. 5897-5918
-
Forskningsöversikt (refereegranskat)abstract
- This paper reviews the use of the Generalized Likelihood Uncertainty Estimation (GLUE) methodology in the 20 years since the paper by Beven and Binley in Hydrological Processes in (1992), which is now one of the most highly cited papers in hydrology. The original conception, the on-going controversy it has generated, the nature of different sources of uncertainty and the meaning of the GLUE prediction uncertainty bounds are discussed. The hydrological, rather than statistical, arguments about the nature of model and data errors and uncertainties that are the basis for GLUE are emphasized. The application of the Institute of Hydrology distributed model to the Gwy catchment at Plynlimon presented in the original paper is revisited, using a larger sample of models, a wider range of likelihood evaluations and new visualization techniques. It is concluded that there are good reasons to reject this model for that data set. This is a positive result in a research environment in that it requires improved models or data to be made available. In practice, there may be ethical issues of using outputs from models for which there is evidence for model rejection in decision making. Finally, some suggestions for what is needed in the next 20 years are provided.
|
|
| 19. |
- Semadeni Davies, Annette, et al.
(författare)
-
The water balance of a sub-Arctic town
- 1999
-
Ingår i: Hydrological Processes. - 1099-1085. ; 13:12-13, s. 1871-1885
-
Tidskriftsartikel (refereegranskat)abstract
- Urban water balances differ from their rural counterparts due to extreme spatial heterogeneity, water imported from outside catchment boundaries and changed flow paths (e.g., drainage pipes and impervious surfaces). Urban catchments are characterized by increased peak discharges and fast response times, each contributing to specific environmental problems. The water balances of towns in the northern high latitudes are further complicated by snow which represents an energy dependent seasonal water store. This paper investigates the monthly water balance of Lulea (June 1992 to June 1996), a Swedish town of 71 000 inhabitants 100 km south of the Arctic Circle. The town has snow cover for five to six months of the year and thaw is usually in late April. Data available included daily precipitation, temperature and inflow to the Uddebo waste water treatment plant; and monthly potential evapotranspiration, groundwater levels and water supply statistics. Of interest were the seasonal differences in runoff volumes and flow pathways to the waste water treatment plant and receiving waters. It was found that increased volumes of runoff, reduced concentration times and long duration led to flooding and high waste water loads at the treatment plant. The surface water component of sewage originates from direct flow into pipe inlets and infiltration into sewer pipes. Autumn and spring were found to be the periods of groundwater recharge, although frozen soil can limit water percolation. Copyright (C) 1999 John Wiley & Sons, Ltd.
|
|
| 20. |
- Oni, Stephen, et al.
(författare)
-
Hydrological footprints of urban developments in the Lake Simcoe watershed, Canada: a combined paired-catchment and change detection modelling approach
- 2015
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 29, s. 1829-1843
-
Tidskriftsartikel (refereegranskat)abstract
- Urban sprawl and regional climate variability are major stresses on surface water resources in many places. The Lake Simcoe watershed (LSW) Ontario, Canada, is no exception. The LSW is predominantly agricultural but is experiencing rapid population growth because of its proximity to the Greater Toronto area. This has led to extensive land use changes that have impacted its water resources and altered run-off patterns in some rivers draining to the lake. Here, we use a paired-catchment approach, hydrological change detection modelling and remote sensing analysis of satellite images to evaluate the impacts of land use change on the hydrology of the LSW (1994 to 2008). Results show that urbanization increased up to 16% in Lovers Creek, the most urban-impacted catchment. Annual run-off from Lovers Creek increased from 239 to 442mm/year in contrast to the reference catchment (Black River at Washago) where run-off was relatively stable with an annual mean of 474mm/year. Increased annual run-off from Lovers Creek was not accompanied by an increase in annual precipitation. Discriminant function analysis suggests that early (1992-1997; pre-major development) and late (2004-2009; fully urbanized) periods for Lovers Creek separated mainly based on model parameter sets related to run-off flashiness and evapotranspiration. As a result, parameterization in either period cannot be used interchangeably to produce credible run-off simulations in Lovers Creek because of greater scatter between the parameters in canonical space. Separation of early and late-period parameter sets for the reference catchment was based on climate and snowmelt-related processes. This suggests that regional climatic variability could be influencing hydrologic change in the reference catchment, whereas urbanization amplified the regional natural hydrologic changes in urbanizing catchments of the LSW. Copyright (c) 2014 John Wiley & Sons, Ltd.
|
|
