04.10.2019
BURG

Benchmarks for Understanding Grasping

In the BURG Project we set out to boost grasping research by focusing on complete tasks and the related object manipulation constraints. In doing so, we need to move from objects to parts, since object parts facilitate the interpretable usage of objects. Parts are essential to know how and where the gripper can grasp given the constraints imposed by the task, e.g., pouring from a container implies grasping from the side. The novelty will come from learning to predict plausible grasps and to link grasps to the parts responsible for selecting each of them. In BURG we will boost grasping research by focusing on complete tasks and the related object manipulation constraints. In doing so, we need to move from objects to parts (Fig. 1), since object parts facilitate the interpretable usage of objects. Parts are essential to know how and where the gripper can grasp given the constraints imposed by the task, e.g., pouring from a container implies grasping from the side. The novelty will come from learning to predict plausible grasps and to link grasps to the parts responsible for selecting each of them.

 

FUNDING:

The project is funded by FWF – Austrian Science Foundation & CHIST-ERA.

  25.06.2019
Active Turbulence Suppression for Aircraft – SmartWings

Atmospheric turbulence is an unsolved problem for aviation impairing economy, safety and comfort. Current efforts to predict turbulence more accurately in order to avoid it by rerouting result in higher fuel consumption and CO2 emissions as well as reduced traffic volumes.

Approaching aircraft in atmospheric turbulence – visualization of local lift distribution and drag

Objective

In the future it should be possible to fly through atmospheric turbulences directly and reliably. The SmartWings research project at ACIN is investigating methods and technologies that are able to reduce the disturbance effects of turbulence, such as vertical accelerations, by as much as 80%.

Störbeschleunigung eines Flugzeugs in atmosphärische Turbulenz ohne und mit Turbulenzunterdrückung

Approach

Smart wing structures measuring turbulences in front of the wing and actively adjusting their shape can suppress disturbance effects of atmospheric turbulences in flight. Calculating optimum flight control outputs from the measured data is a particular control engineering challenge. It is solved by a combination of model-based feedforward and feedback control.

Highly dynamic lift control: Through the application of direct lift control, the wing lift can be varied very quickly. A novel control procedure prevents secondary short-period oscillation and thus considerably increases the lifting effect that can be achieved.

Phase compensation: Using anticipating sensors, such as pressure measurements in front of the wing or wind LiDAR, it is possible to compensate system-related time delays and the disturbances precisely at the right moment.

Adaptive structures: Innovative materials and manufacturing methods enable the use of adaptive wing structures (morphing wings) in order to adapt the wing shape specifically to the external flow field.

Applications

Active Turbulence Suppression may be applied to fixed-wing airplanes of different sizes – from micro UAV to long-haul aircraft. An essential prerequisite for implementation is a digital flight control and technical equipment on the wing in order to vary the lift quickly. For this purpose, conventional wing flaps or, in the future, novel wing structures with adaptive elements may be used.

Related Publications

Journal articles

  • A. Galffy, R. Gaggl, R. Mühlbacher, D. Frank, J. Schlarp, and G. Schitter, Turbulence load prediction for manned and unmanned aircraft by means of anticipating differential pressure measurements, CEAS Aeronautical Journal, vol. 12, 2021.
    [BibTex] [Download] 
    @article{TUW-292332,
author = {Galffy, Andras and Gaggl, Rainer and M{\"u}hlbacher, Robert and Frank, Daniel and Schlarp, Johannes and Schitter, Georg},
title = {Turbulence load prediction for manned and unmanned aircraft by means of anticipating differential pressure measurements},
journal = {CEAS Aeronautical Journal},
year = {2021},
volume = {12},
doi = {10.1007/s13272-021-00512-y},
keywords = {atmospheric turbulence, disturbance prediction, turbulence suppression, gust load alleviation}
}

Conference papers

  • A. Galffy, J. Schlarp, D. Frank, R. Mühlbacher, and G. Schitter, Turbulence prediction for aircraft by means of high-dynamic differential pressure measurements, in Proceedings of the Aerospace Europe Conference AEC2020, 2020.
    [BibTex] [Download] 
    @inproceedings{TUW-292322,
author = {Galffy, Andras and Schlarp, Johannes and Frank, Daniel and M{\"u}hlbacher, Robert and Schitter, Georg},
title = {Turbulence prediction for aircraft by means of high-dynamic differential pressure measurements},
booktitle = {Proceedings of the Aerospace Europe Conference AEC2020},
year = {2020},
keywords = {atmospheric turbulence, disturbance prediction, turbulence suppression, gust load alleviation},
note = {Vortrag: Aerospace Europe Conference AEC2020, Bordeaux, France; 2020-02-25 -- 2020-02-28}
}
  • A. Galffy, F. Car, and G. Schitter, Calibration and flight test of a 3D printed 5-hole probe for high-dynamic wind measurements for UAV, in Proceedings of the International Workshop on Research, Education and Development on Unmanned Aerial Systems, 2019.
    [BibTex] [Download] 
    @inproceedings{TUW-282543,
author = {Galffy, Andras and Car, Florian and Schitter, Georg},
title = {Calibration and flight test of a 3D printed 5-hole probe for high-dynamic wind measurements for UAV},
booktitle = {Proceedings of the International Workshop on Research, Education and Development on Unmanned Aerial Systems},
year = {2019},
numpages = {10},
doi = {10.1109/REDUAS47371.2019.8999671},
note = {Vortrag: International Workshop on Research, Education and Development on Unmanned Aerial Systems, Cranfield, United Kingdom; 2019-11-25 -- 2019-11-27}
}

Project Partners

Turbulence Solutions GmbH
T.I.P.S. Messtechnik GmbH
Actaron GmbH

Press Release

https://noe.orf.at/

https://www.sn.at/

https://diepresse.com/

https://www.krone.at/

Funding

funded under the program Take Off of the Austrian Federal Ministry for Transport, Innovation and Technology (bmvit)

  12.12.2018
Klimafloor

Project focus

  • Development of an automated robot for the leveling of pour-in insulation
  • Evaluation of different control strategies
  • Vision-based path planning for obstacle avoidance and optimal distribution of the material

Description

The project deals with the total installation and processing of floor structures including underfloor heating of our industrial partner mixit Dämmstoffe GmbH. In the field of house constructions, the leveling of screed or pour-in insulation is considered an exhausting and harmful task for the construction workers. In order to overcome these issues, our focus in the project lies on the construction of an automated leveling robot in order to increase the distribution quality and achieve a shorter processing time. The robot system consists of several modular components, which allows fast and easy transportation and assembly. To ensure that the working tool stays level, a rotational laser is set up as guidance. In order to avoid contact with obstacles, e.g. walls, distance sensors and a 3D camera are used.

Automation and control of the leveling platform

As a first prototype, an existing platform was used as a starting point. This platform has a SCARA-like structure with a two-linked arm mounted on a foldable tripod and uses a projected laser line to automatically adjust the tool height, while the rest of the system is operated manually. As the base has to be leveled during each new set-up, automation of this process saves a considerable amount of time. In order to facilitate this, two servomotors were mounted on the height-setting screws on the legs and a tilt sensor was added to provide the measurements needed for feedback control. The automatic leveling also allows us to accurately estimate the leg positions without direct measurement, which is later useful during the path planning phase.

Automated robot platform for the leveling of pour-in insulation

For the movement of the arm itself, larger synchronous servomotors were added to each of the three joints in a belt drive configuration. Through inverse kinematics and dynamics, these actuators allow precise control over the end-effector position. Motor torque is also measured and will enable us to use more advanced control strategies, such as impedance control, avoiding potentially harmful hard contact with obstacles.

A novel laser line detector is developed to provide the needed accuracy. With the aim of better suit the intended task, new designs for the robot tool are developed and tested in a construction site environment.

Vision-based obstacle detection and path planning

For the detection of the walls in the 3D point cloud, the Sequential RANSAC (Random Sample Consensus) algorithm is used. In future evaluations, also algorithms such as MultiRANSAC or Residual Histogram Analysis can be tested.

Point cloud of robot during leveling process

The first step in the vision-based path planning is to obtain the knowledge of the to be processed plane. This is done by detecting the laser line of the rotational laser. With the camera mounted on top of the robot, the plane can be calculated. Subsequently, areas with too much or too less material can be perceived.

Related publications

  • M. Bibl, R. Stein, E. Döberl, and G. Schitter, Rotierender optischer Positions- und Winkelsensor, E&I Elektrotechnik und Informationstechnik, vol. 135, iss. 6, p. 396–400, 2018.
    [BibTex] 
    @Article{TUW-272096,
author = {Bibl, Matthias and Stein, Robert and D{\"o}berl, Egon and Schitter, Georg},
title = {Rotierender optischer Positions- und Winkelsensor},
journal = {E{\&}I Elektrotechnik und Informationstechnik},
year = {2018},
volume = {135},
number = {6},
pages = {396--400},
keywords = {Positions- und Winkelmessung, Rotierender optischer Sensor, Optische Messtechnik},
doi = {10.1007/s00502-018-0642-3}
}
  • M. Hurban, M. Melik-Merkumians, M. Steinegger, M. Bibl, P. Gsellmann, and G. Schitter, Automated Tripod Leveling and Parameter Estimation for a Granular-fill Insulation Distributing Robot, in Proceedings of the Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019), 2019.
    [BibTex] [Download] 
    @InProceedings{TUW-282489,
author = {Hurban, Milan and Melik-Merkumians, Martin and Steinegger, Michael and Bibl, Matthias and Gsellmann, Peter and Schitter, Georg},
title = {Automated Tripod Leveling and Parameter Estimation for a Granular-fill Insulation Distributing Robot},
booktitle = {Proceedings of the Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019)},
year = {2019},
volume = {52/15},
note = {Vortrag: Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019), Wien; 2019-09-04 -- 2019-09-06},
doi = {10.1016/j.ifacol.2019.11.678},
journal = {IFAC-PapersOnLine/Elsevier},
keywords = {Robotic manipulators, Linearization, Kalman Filters, Parameter estimation, LQG control method},
numpages = {6},
}

Project partners

Funding

  05.11.2018
RoboCoop

Robotics Education driven by Interregional  Cooperation

In schools and universities, there is at this moment a lack of interest in the MINT subjects (mathematics, informatics, natural sciences and technology) and in well-trained teachers for these subjects in Austria and Slovakia. Women, in particular, are clearly underrepresented in the MINT areas. This leads to bottlenecks in the job market, although there is an increasing demand for MINT personnel in the whole region. Robotics in education has proven to be a valuable tool for practical learning, not only for robotics itself, but for MINT topics in general. RoboCoop is a unique project aimed at exploiting the multidisciplinary potential of robotics and establishing cross-border educational activities to raise interest in MINT issues.

In RoboCoop, more than 4000 pupils, students and innovative MINT educators will be encouraged and engaged at interregional level to serve as a positive example of a wider use at national level in the two countries. To this end, 2 x 4 hours of workshops will be held at ACIN in which students will get to know the world of robots and foster their creativity and collaboration skills. The didactic concept alternates between instructive and constructive elements. In addition, a comprehensive quantitative and qualitative evaluation of all project activities should lead to policy recommendations in order to ensure a systematic and long-term implementation of the project ideas and thus to an early introduction of robotics topics at secondary level.

Partners:

TU Wien – Fakultät für Elektrotechnik und Informationstechnik

ACIN Institut für Automatisierungs- und Regelungstechnik

PRIA – Practical Robotics Institute Austria

SSR Wien – Stadtschulrat Wien

SUK – Slovak University of Technology in Bratislava

CVTI SR – Slovak Centre of Scientific and Technical Information

FUNDING:

The project is funded by the cooperation programme Interreg V-A SK-AT with the project number V212.

  24.11.2017
iBridge

The iBridge project is a cross-generational project aimed at increasing the interest of children and pupils in the social and cross-cultural research topics and innovation as well as deepening their relationship to science through the application of robotics in the elderly care technologies. For these purposes the children and pupils will develop innovative “sensitive cuddly animal” as well as other service robots concepts, already well proven in the elderly care. Additionally, the pupils will support the older generation by providing access to modern technologies through PC / internet courses, learning and paying attention to their needs.

  18.10.2017
High-precision electrical AFM modes for biological applications

Electrical modes of Atomic Force Microscopy (AFM) allow the high-resolution mapping of surface charges on a sample with nanometer precision. A particular measurement challenge is to perform such modes on biological samples (tissue extracts, biomolecules, biomembranes, etc). To this end, the project aims to investigate different preparation and measurement approaches and a specific goal is to determine alterations of surface charge of biological fibers caused by the reaction with sugar, which has important implications in medicine and cell biology.

Figure 1: KFM surface potential map of a collagen fibril on graphite. The bright spots show areas of positive charge.

 

Project focus

  • Determine the influence of humidity on ionised, chemical surface groups
  • Investigate the charge of glycated protein fibrils

Related publications

Project partners/collaborators

  07.09.2017
High resolution long range Lidar for autonomous driving (LiDcAR)

Project focus

  • Evaluation and control of scanning systems for Lidar applications
  • Precision metrology for MEMS scanning mirrors
  • Modeling and identification of Complex dynamics of MEMS scanning mirror
  • Advanced sensing and control for MEMS scanning mirror
  • Performance assessments of the MEMS scanning systems for automotive lidar

Description

Lidar is an acronym for light detection and ranging, in analogy to radar. Lidar has received much attention in the automotive industry as a key component for high level automated driving systems. Compared to other sensing techniques such as stereo cameras and radar, lidar can provide high resolution and highly accurate 3D measurements of the surroundings and robust detection in various weather conditions. The lidar sensors are expected to ensure the safety in automated driving applications such as collision detection, blind spot monitoring, object and pedestrian recognition, and terrain mapping. Currently Google, BMW, Ford, Volvo and other autonomous car developers include lidar sensors in their systems for safe driving.

(Left) Line scan lidar based on a 1D resonant MEMS mirror and a detector array. (Right) Example of a 1D resonant MEMS mirror with electrostatic comb-drive actuation.

The main challenges of this project are in the development and evaluation of the scanning system in the lidar sensor. Currently a polygon scanner, MEMS mirror and optical phase arrays are studied for the potential scanning system. The scanning system for the lidar for autonomous driving requires extreme robustness in harsh environmental conditions, i.e. large temperature range, humidity, dust, shock, and vibration. The scanning system in lidar should provide seamless operation to ensure the safety of the drivers and pedestrians. In addition, the performance of the lidar sensor is defined and measured precisely to ensure the safety requirements with sufficient accuracy.

This project aimed to develop precise and robust scanning systems for lidars. The research includes investigation of the various scanning techniques as well as the methodology to evaluate the performance of the lidar and its scanning system. The developed lidar and evaluation platform was mounted on a vehicle and tested in the field.

Precision metrology of MEMS scanning mirrors

For accurate evaluation of MEMS scanning mirrors, systematic errors of the measurement setup have to be identified and avoided. Hence, a self-calibrated test bench is developed and analyzed regarding its uncertainties of MEMS mirror angle detection. The basic principle is that a laser beam gets deflected by the MEMS mirror and is detected by a position sensitive detector (PSD), where the mirror angle can be recalculated. As alignment uncertainties such as an inaccurate placement of the MEMS mirror in its package cause estimation errors, a semi-automated calibration procedure is developed based on a CCD camera and a motorized stage. The achieved accuracy error of 0.025° at 15° mechanical angle suffices the requirements for automotive Lidar. As a crucial component of the test bench, the PSDs are analyzed regarding the achievable bandwidth while also temperature drifts as well as their compensation schemes are investigated.

(Left) MEMS test bench with semi-automated calibration and alignment capabilities. (Right) Uncertainty analysis of MEMS mirror angle detection and component-wise contribution.

Accurate modeling of the MEMS scanning mirror

Accurate modelling and identification of resonant MEMS mirrors dynamics is crucial for control design and allows to identify weaknesses and strengths of the individual MEMS mirror designs. In the presence of nonlinearities, conventional linear system theory fails to predict the behavior of the system as it gets state dependent. In particular, MEMS mirrors exhibit several nonlinearities, such as amplitude dependent damping, angle dependent stiffness as well as actuation forces, which depend on the angular comb-drive capacitance derivative and the driving voltage squared. Hence, an identification method for a general single degree of freedom model was developed to estimate the system parameters solely by measurement data with a minimum on prior assumptions. For advanced control design, a linearized model based on period-to-period energy conservation was developed, which represents the local MEMS mirror dynamics of phase, frequency and amplitude at a nominal operation point. As an extension, slow flow analysis was applied to the identified nonlinear model, which allows a fast calculation of the global and local behavior of the MEMS mirror.

(Left) Comparison of measured and simulated frequency response. (Right) Comparison of measured and simulated frequency response of the local dynamics at the nominal operation point.

Advanced sensing and control for MEMS mirrors

A precise sensing of the MEMS mirror movement is crucial for robust feedback control. As the size of the MEMS mirror is in the range of view millimeters, dedicated sensors can hardly be applied without complicating the design or increasing production cost. Hence, self-sensing approaches are developed, where the same comb-drives serve as actuators and sensors. The comb-drive capacitance of resonant MEMS mirrors usually has a triangular shape with its maximum at zero angle and deceases in both angular directions in a deterministic manner. Therefore, the measurement of the capacitance directly reveals the mirror angle. For square wave excitation of the MEMS mirror, the charge on the comb-drive capacitance is direct proportional to the capacitance and therefore serves as an angle sensor. However, the measurement time is limited to the time where the driving voltage is on, which lead to the development of a switched input observer to estimate the MEMS mirror angle also between the measurement windows, i.e. where the driving voltage is off.

(Left) Switched input observer scheme for self-sensing mirror trajectory estimation. (Right) Convergence of the switched input observer and comparison with the true angle measurement (PSD). The observer obtains the sense signal only, while the PSD is only for evaluation.

A precise zero crossing measurement is obtained by the displacement current flowing through the comb-drives during a constant driving voltage as depicted in Fig. 4. The current signal shows a sharp zero crossing when the mirror passes zero angle, which can be precisely detected by a simple comparator.

(Left) Example of trajectory, driving signal and current signal. (Right) Scheme of the DAsPLL.

For performance evaluation of the phase detection, the Digital Asynchronous PLL (DAsPLL) was developed, which operates the MEMS mirror with immediate phase error compensation and showed a center pixel uncertainty error of less than 0.3 mdeg at 58° field of view. Key feature of the DAsPLL is the asynchronous switching off of the driving voltage by bypassing the zero crossing comparator detection signal without clock speed limitations of the FPGA.

Also a conventional PLL structure was analyzed, where the driving frequency is adjusted according to the measured phase errors with an appropriate control law. The derived linear models of the MEMS mirror allowed a simple and robust control design and revealed that due to the nonlinear stiffness of the MEMS mirror, a proportional gain is crucial as only integral control leads to large settling times of the system or even instability.

(Left) Conventional PLL structure. (Right) Root locus of closed loop system model and dependency on proportional and integral gain of the PLL controller.

Applications

  • Lidar for autonomous driving
  • Precision measurement system

Related Publications and Patents

Journal articles

  • D. Brunner, H. W. Yoo, and G. Schitter, Linear Modeling and Control of Comb-Actuated Resonant MEMS Mirror with Nonlinear Dynamics, IEEE Transactions on Industrial Electronics, vol. 68, iss. 4, p. 3315–3323, 2021.
    [BibTex] [Download] 
    @article{TUW-288425,
author = {Brunner, David and Yoo, Han Woong and Schitter, Georg},
title = {Linear Modeling and Control of Comb-Actuated Resonant MEMS Mirror with Nonlinear Dynamics},
journal = {IEEE Transactions on Industrial Electronics},
year = {2021},
volume = {68},
number = {4},
pages = {3315--3323},
doi = {10.1109/TIE.2020.2982124},
keywords = {Energy conservation, laser radar, linearization techniques, microelectromechanical system (MEMS), micromirrors, nonlinear systems, parameter estimation, phase locked loops (PLL), system identification.}
}
  • H. W. Yoo, S. Albert, and G. Schitter, Accurate Analytic Model of a Parametrically Driven Resonant MEMS Mirror with a Fourier Series Based Torque Approximation, Journal of Microelectromechanical Systems, vol. 29, iss. 6, p. 1431–1442, 2020.
    [BibTex] [Download] 
    @article{TUW-290470,
author = {Yoo, Han Woong and Albert, Stephan and Schitter, Georg},
title = {Accurate Analytic Model of a Parametrically Driven Resonant MEMS Mirror with a Fourier Series Based Torque Approximation},
journal = {Journal of Microelectromechanical Systems},
year = {2020},
volume = {29},
number = {6},
pages = {1431--1442},
doi = {10.1109/JMEMS.2020.3024752},
keywords = {Mirrors , Micromechanical devices , Torque , Analytical models , Mathematical model , Capacitance , Fourier series}
}
  • D. Brunner, H. W. Yoo, and G. Schitter, Precise phase control of resonant MOEMS mirrors by comb-drive current feedback, Mechatronics, vol. 71, p. 102420, 2020.
    [BibTex] [Download] 
    @article{TUW-290167,
author = {Brunner, David and Yoo, Han Woong and Schitter, Georg},
title = {Precise phase control of resonant MOEMS mirrors by comb-drive current feedback},
journal = {Mechatronics},
year = {2020},
volume = {71},
pages = {102420},
doi = {10.1016/j.mechatronics.2020.102420},
keywords = {Comb-drive, Digital asynchronous phase locked loop (DAsPLL), Micro-opto-electro-mechanical system (MOEMS), Nonlinear systems, Precision control, Resonant scanning mirror}
}
  • H. W. Yoo, N. Druml, D. Brunner, C. Schwärzl, T. Thurner, M. Hennecke, and G. Schitter, MEMS-based lidar for autonomous driving, E&I Elektrotechnik und Informationstechnik, vol. 135, iss. 6, p. 408–415, 2018.
    [BibTex] [Download] 
    @Article{TUW-273071,
author = {Yoo, Han Woong and Druml, N. and Brunner, David and Schw{\"a}rzl, Christian and Thurner, Thomas and Hennecke, Markus and Schitter, Georg},
title = {MEMS-based lidar for autonomous driving},
journal = {E{\&}I Elektrotechnik und Informationstechnik},
year = {2018},
volume = {135},
number = {6},
pages = {408--415},
keywords = {lidar; MEMS scanning mirror; autonomous driving; metrology platform},
doi = {10.1007/s00502-018-0635-2},
}

Conference papers

  • R. Schroedter, H. W. Yoo, D. Brunner, and G. Schitter, Capacitive Charge-based Self-Sensing for Resonant Electrostatic MEMS mirrors, in Proceedings of the 21st IFAC World Congress, 2020.
    [BibTex] [Download] 
    @inproceedings{TUW-292461,
author = {Schroedter, Richard and Yoo, Han Woong and Brunner, David and Schitter, Georg},
title = {Capacitive Charge-based Self-Sensing for Resonant Electrostatic MEMS mirrors},
booktitle = {Proceedings of the 21st IFAC World Congress},
year = {2020},
numpages = {6},
keywords = {Resonant MEMS mirror, electrostatic comb drive, capacitive charge sensing, nonlinear observer with switched input},
note = {Vortrag: 21st IFAC World Congress, Berlin; 2020-07-12 -- 2020-07-17}
}
  • H. W. Yoo and G. Schitter, Complex Valued State Space Model for Weakly Nonlinear Duffing Oscillator with Noncollocated External Disturbance, in Proceedings of the 21st IFAC World Congress, 2020.
    [BibTex] [Download] 
    @inproceedings{TUW-290466,
author = {Yoo, Han Woong and Schitter, Georg},
title = {Complex Valued State Space Model for Weakly Nonlinear Duffing Oscillator with Noncollocated External Disturbance},
booktitle = {Proceedings of the 21st IFAC World Congress},
year = {2020},
numpages = {7},
keywords = {Duffing oscillator, complex valued model, perturbation theory, disturbance model, noncollocated disturbance, MEMS mirror, automotive lidar},
note = {Vortrag: 21st IFAC World Congress, Berlin; 2020-07-12 -- 2020-07-17}
}
  • D. Brunner, H. W. Yoo, and G. Schitter, Digital Asynchronous Phase Locked Loop for Precision Control of MOEMS Scanning Mirror, in Proceedings of the Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019), 2019.
    [BibTex] [Download] 
    @InProceedings{TUW-282514,
author = {Brunner, David and Yoo, Han Woong and Schitter, Georg},
title = {Digital Asynchronous Phase Locked Loop for Precision Control of MOEMS Scanning Mirror},
booktitle = {Proceedings of the Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019)},
year = {2019},
volume = {52/15},
note = {Vortrag: Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019), Wien; 2019-09-04 -- 2019-09-06},
doi = {10.1016/j.ifacol.2019.11.647},
journal = {IFAC-PapersOnLine/Elsevier},
keywords = {Digital asynchronous phase locked loop (DAsPLL), Micro-Opto-Electro-Mechanical System (MOEMS), Resonant scanning mirror, Comb-drive, Nonlinear systems.},
numpages = {6},
}
  • H. W. Yoo, D. Brunner, T. Thurner, and G. Schitter, MEMS Test Bench and its Uncertainty Analysis for Evaluation of MEMS Mirrors, in Proceedings of the Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019), 2019.
    [BibTex] [Download] 
    @InProceedings{TUW-283447,
author = {Yoo, Han Woong and Brunner, David and Thurner, Thomas and Schitter, Georg},
title = {MEMS Test Bench and its Uncertainty Analysis for Evaluation of MEMS Mirrors},
booktitle = {Proceedings of the Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019)},
year = {2019},
volume = {52/15},
note = {Vortrag: Joint Conference 8th IFAC Symposium on Mechatronic Systems (MECHATRONICS 2019), and 11th IFAC Symposium on Nonlinear Control Systems (NOLCOS 2019), Wien; 2019-09-04 -- 2019-09-06},
doi = {10.1016/j.ifacol.2019.11.648},
journal = {IFAC-PapersOnLine/Elsevier},
keywords = {Metrology, Uncertainty analysis, Characterization, Microelectromechanical systems (MEMS), MEMS mirror},
numpages = {6},
}
  • D. Brunner, H. W. Yoo, T. Thurner, and G. Schitter, Data based Modelling and Identification of Nonlinear SDOF MOEMS Mirror, in MOEMS and Miniaturized Systems XVIII, 2019.
    [BibTex] [Download] 
    @InProceedings{TUW-282507,
author = {Brunner, David and Yoo, Han Woong and Thurner, Thomas and Schitter, Georg},
title = {Data based Modelling and Identification of Nonlinear SDOF MOEMS Mirror},
booktitle = {MOEMS and Miniaturized Systems XVIII},
year = {2019},
volume = {10931},
note = {Vortrag: SPIE Photonics West 2019, San Francisco, California, USA; 2019-02-02 -- 2019-02-07},
doi = {10.1117/12.2508429},
journal = {SPIE},
keywords = {Micro-Opto-Electro-Mechanical System (MOEMS), Resonant scanning mirror, Data based identification, Generalized nonlinear SDOF model, Actuated decay, Comb-drive torque},
numpages = {11},
}
  • H. W. Yoo, D. Brunner, T. Thurner, and G. Schitter, Compensation for Temperature Dependency of 1D Position Sensitive Detector, in Advances in Display Technologies IX, 10942, 2019.
    [BibTex] [Download] 
    @InProceedings{TUW-283433,
author = {Yoo, Han Woong and Brunner, David and Thurner, Thomas and Schitter, Georg},
title = {Compensation for Temperature Dependency of 1D Position Sensitive Detector},
booktitle = {Advances in Display Technologies IX},
year = {2019},
address = {10942},
publisher = {SPIE},
note = {Vortrag: SPIE Photonics West 2019, San Francisco, California, USA; 2019-02-02 -- 2019-02-07},
doi = {10.1117/12.2508403},
keywords = {Position sensitive detector (PSD), High temperature operation, Leakage current, Point drift measurement, Reliability test}
}

Patents

  • H. W. Yoo, M. E. Hennecke, G. Schitter, and T. Thurner, Real time gating and signal routing in laser and detector arrays for lidar applications, U.S. Patent, iss. US 2020/0200877 A1, 2020.
    [BibTex] 
    @patent{TUW-292557,
author = {Yoo, Han Woong and Hennecke, Markus Edward and Schitter, Georg and Thurner, Thomas},
title = {Real time gating and signal routing in laser and detector arrays for lidar applications},
journal = {U.S. Patent},
number = {US 2020/0200877 A1},
year = {2020},
note = {eingereicht: 2019-02-01, erteilt: 2020-06-25}
}
  • H. W. Yoo, M. E. Hennecke, G. Schitter, and T. Thurner, Echtzeit-gating und Signal Wegleitung in Laser- und Detektorarrays für LiDAR-Anwendungen, Deutsches Patent- und Markenamt, iss. DE 10 2019 220 289 A1, 2020.
    [BibTex] 
    @patent{TUW-292552,
author = {Yoo, Han Woong and Hennecke, Markus Edward and Schitter, Georg and Thurner, Thomas},
title = {Echtzeit-gating und Signal Wegleitung in Laser- und Detektorarrays f{\"u}r LiDAR-Anwendungen},
journal = {Deutsches Patent- und Markenamt},
number = {DE 10 2019 220 289 A1},
year = {2020},
note = {eingereicht: 2019-12-19, erteilt: 2020-06-25}
}
  • T. Thurner, D. Brunner, M. E. Hennecke, G. Schitter, and H. W. Yoo, LiDAR-Sensoren und Verfahren für LiDAR-Sensoren, Deutsches Patent- und Markenamt, iss. DE 10 2018 128 164 A1, 2020.
    [BibTex] 
    @patent{TUW-292555,
author = {Thurner, Thomas and Brunner, David and Hennecke, Markus Edward and Schitter, Georg and Yoo, Han Woong},
title = {LiDAR-Sensoren und Verfahren f{\"u}r LiDAR-Sensoren},
journal = {Deutsches Patent- und Markenamt},
number = {DE 10 2018 128 164 A1},
year = {2020},
howpublished = {Patent},
note = {eingereicht: 2018-11-12, erteilt: 2020-05-14}
}
  • T. Thurner, D. Brunner, M. E. Hennecke, G. Schitter, and H. W. Yoo, Lidar sensors and methods for lidar sensors, U.S. Patent, iss. US 2020/0150246 A1, 2020.
    [BibTex] 
    @patent{TUW-292556,
author = {Thurner, Thomas and Brunner, David and Hennecke, Markus Edward and Schitter, Georg and Yoo, Han Woong},
title = {Lidar sensors and methods for lidar sensors},
journal = {U.S. Patent},
number = {US 2020/0150246 A1},
year = {2020},
howpublished = {Patent},
note = {eingereicht: 2019-11-11, erteilt: 2020-05-14}
}

Press Release

Project partners

Funding

  28.08.2017
Modeling and optimal control of electric machines with redundant stator windings

Project focus

  • Modeling of PMSM with redundant stator windings
  • Detection of failures of the PMSM
  • Optimal fail-safe control of PMSM with redundant stator windings

Description

Permanent magnet synchronous machines (PMSM) are used in numerous industrial and automotive applications due to their high power to size ratio. In some of these applications (e.g., electric power steering systems), a fault of the motor (e.g., short circuit of stator windings or open connection of the stator coils), the inverter or the sensors (position or current sensor) can yield an undesired and even potentially dangerous behavior. To allow for an operation of the PMSM even in case of a fault, constructions with redundant stator windings and inverter legs have been proposed in literature, see, e.g. Fig. 1. Although there is a large variety of possible motor constructions, the main idea is to have more than three stator phases which are controlled by independent inverter legs. This allows for an operation, probably with decreased performance, of the PMSM in case of a single fault. Moreover, utilizing a position estimation strategy for PMSMs without a dedicated position sensor gives a fall back solution in case of a position sensor fault.

Setup of the stator windings with a single three-phase and a dual three-phase system

The majority of fail-safe control strategies and sensorless position estimation methods are based on a magnetically linear fundamental wave dq-model of the PMSM. In this research cooperation with Robert Bosch GmbH, strategies for the fault detection, the fail-safe operation and the optimal (position sensorless) control of permanent magnet synchronous machines with redundant stator windings are developed, which are capable to systematically take into account magnetic saturation and non-fundamental wave characteristics of the magnetic field. The basis for the design is a description of the PMSM by magnetic equivalent circuits, which allow to derive models of moderate complexity suitable for the analysis and the controller design. The resulting estimation and control strategies are intended to be utilized in automotive applications, as, e.g., electric power steering systems or electric drive trains.

Project partners

  25.08.2017
Modeling and control of injection molding machines

Project focus

  • Model-based design of optimal control strategies for the injection and holding pressure phase
  • Model-based control of the temperature distribution in injection molding machines
  • Application to injection molding machines with hydraulic direct drives

Description

Injection molding is the most prominent way to produce components made of plastics. In the injection molding process, plastics is liquefied by means of heating and deformation of the granulate. The liquid plastics is accumulating in the screw antechamber. If the screw is moved forward, the liquid fluid is injected into the mold. After sufficiently cooling down, the final plastics part can be taken out of the mold and the process can begin again.

Photo of an injection molding machine

To obtain a high product quality during production, the stability of the injection process from one injection cycle to the next is of outmost importance. The main process variables in injection machines are the temperatures, the injection velocities and the injection pressures. Suitable control strategies are therefore necessary to obtain exact and reproducible tracking of the desired values for these quantities. In this research project in cooperation with Engel, optimal control strategies are developed for the injection and holding pressure phase (velocity, pressure) as well as the temperature for injection molding machines. One focus of this project lies on hydraulic actuated injection molding machines with hydraulic direct drive (servo-pump), which feature an improved energy efficiency compared to valve controlled machines. The control of these machines is particularly demanding due to the reduced dynamics of the actuation system.

Project partners

  24.08.2017
Modeling and optimal control of permanent magnet synchronous motors

Project focus

  • Magnetic equivalent circuit modeling of permanent magnet synchronous motors (PMSM)
  • Systematic incorporation of magnetic saturation and non-sinusoidal field characteristics
  • Optimal torque control
  • Sensorless methods for the position estimation of PMSM

Description

Permanent magnet synchronous motors (PMSM) are applied in many industrial applications as e.g. robotics due to their high torque capabilities and their high energy efficiency. Field-oriented control is the industrial standard for the control of PMSMs. This control strategy is based on a transformation of the angle-dependent quantities of the PMSM on a dq0-coordinate frame which is fixed with the rotor. The design is typically based on the assumption of magnetic linearity and sinusoidal field characteristics of the PMSM.

Modern motor constructions frequently apply single tooth windings and an inhomogeneous air gap. This results in PMSMs where the assumption on a sinusoidal field characteristics is more or less violated. Moreover, PMSM are frequently operated up to regions with significant magnetic saturation. Thus, the assumption of the classical field-oriented control are frequently more or less violated in many practical applications.

In this research cooperation with Bernecker and Rainer Industrieelektronik GmbH (B&R), methods for systematic mathematical description of PMSMs with pronounced magnetic saturation and non-sinusoidal field characteristics are examined. Here, the magnetic equivalent circuit modeling (MEC) approach, which is based on an approximation of the magnetic system of the PMSM by magnetic resistances (reluctances) and magneto-motive force-sources (coils, permanent magnets), see Fig. 1.

Cross-sectional view and possible magnetic equivalent circuit of a typical PMSM

Network theory, which is well known from electric circuits, is utilized to systematically obtain the mathematical model for arbitrary motor construction with rather complex magnetic equivalent networks, see, e.g., Fig. 2. Moreover, it is easily possible to systematically include magnetic saturation and non-sinusoidal field characteristics.

Magnetic equivalent circuit of a typical PMSM

The resulting MEC-models feature a rather low model complexity, which makes them suitable for a model-based design of control strategies. In this research project optimal control strategies for the indirect torque control of PMSMs, while minimizing the losses of the PMSM at the same time, are developed. These control strategies allow to significantly improve the torque control accuracy in comparison to a classical field oriented control strategy (dq), see, e.g., Fig. 3.

Torque control accuracy of the proposed optimal control strategy in comparison to a field-oriented control (dq)

The model-based approach allows to easily adopt the control strategies to other construction sizes and types of PMSMs. In particular, the control strategies can also be applied to linear motors. Moreover, the developed mathematical models are a good basis for the sensorless estimation of the position of PMSM.

Selected publications

  • D. Faustner, W. Kemmetmüller, and A. Kugi, Flatness-Based Torque Control of Saturated Surface-Mounted Permanent Magnet Synchronous Machines, IEEE Transactions on Control Systems Technology, vol. 24, iss. 4, p. 1201–1213, 2016.
    [BibTex] [Download] 
    @Article{Faustner16,
Title = {Flatness-Based Torque Control of Saturated Surface-Mounted Permanent Magnet Synchronous Machines},
Author = {Faustner, D. and Kemmetm{\"u}ller, W. and Kugi, A.},
Journal = {IEEE Transactions on Control Systems Technology},
Pages = {1201--1213},
Volume = {24},
Year = {2016},
Number = {4},
Doi = {10.1109/TCST.2015.2501345},
ISSN = {1063-6536},
}
  • D. Faustner, W. Kemmetmüller, and A. Kugi, Experimental Parameterization of a Design Model for Flatness-Based Torque Control of a Saturated Surface-Mounted PMSM, in Proceedings of the 7th IFAC Symposium on Mechatronic Systems & 15th Mechatronics Forum International Conference, Loughborough, UK, 2016, p. 575–582.
    [BibTex] 
    @InProceedings{Faustner16a,
author = {Faustner, D. and Kemmetm\"uller, W. and Kugi, A.},
title = {Experimental Parameterization of a Design Model for Flatness-Based Torque Control of a Saturated Surface-Mounted PMSM},
booktitle = {Proceedings of the 7th IFAC Symposium on Mechatronic Systems \& 15th Mechatronics Forum International Conference},
year = {2016},
volume = {49},
number = {21},
month = {9},
pages = {575--582},
doi = {10.1016/j.ifacol.2016.10.663},
address = {Loughborough, UK},
issn = {2405-8963},
}
  • D. Faustner, W. Kemmetmüller, and A. Kugi, Magnetic Equivalent Circuit Modeling of a Saturated Surface-Mounted Permanent Magnet Synchronous Machine, in Proceedings of the 8th Vienna International Conference on Mathematical Modelling (MATHMOD), Vienna, Austria, 2015, p. 360–365.
    [BibTex] 
    @InProceedings{Faustner15,
author = {Faustner, D. and Kemmetm\"uller, W. and Kugi, A.},
title = {Magnetic Equivalent Circuit Modeling of a Saturated Surface-Mounted Permanent Magnet Synchronous Machine},
booktitle = {Proceedings of the 8th Vienna International Conference on Mathematical Modelling (MATHMOD)},
year = {2015},
month = {2},
pages = {360--365},
doi = {10.1016/j.ifacol.2015.05.033},
address = {Vienna, Austria},
}
  • D. Faustner, W. Kemmetmüller, and A. Kugi, Field Weakening in Flatness-Based Torque Control of Saturated Surface-Mounted Permanent Magnet Synchronous Machines, in Proceedings of the 2015 IEEE Conference on Control Applications (CCA), Sydney, Australia, 2015, p. 858–863.
    [BibTex] 
    @InProceedings{Faustner15a,
author = {Faustner, D. and Kemmetm\"uller, W. and Kugi, A.},
title = {Field Weakening in Flatness-Based Torque Control of Saturated Surface-Mounted Permanent Magnet Synchronous Machines},
booktitle = {Proceedings of the 2015 IEEE Conference on Control Applications (CCA)},
year = {2015},
publisher = {IEEE},
month = {9},
pages = {858--863},
doi = {10.1109/CCA.2015.7320725},
address = {Sydney, Australia},
}
  • W. Kemmetmüller, D. Faustner, and A. Kugi, Optimale Nichtlineare Regelung von permantenterregten Synchronmaschinen, at – Automatisierungstechnik, vol. 63, iss. 9, p. 739–750, 2015.
    [BibTex] [Download] 
    @Article{Kemmetmueller15a,
Title = {Optimale Nichtlineare Regelung von permantenterregten Synchronmaschinen},
Author = {Kemmetm\"uller, W. and Faustner, D. and Kugi, A.},
Journal = {at -- Automatisierungstechnik},
Pages = {739--750},
Volume = {63},
Year = {2015},
Number = {9},
Doi = {10.1515/auto-2015-0041},
}
  • W. Kemmetmüller, D. Faustner, and A. Kugi, Optimal torque control of permanent magnet synchronous machines using magnetic equivalent circuits, Mechatronics, vol. 32, p. 22–33, 2015.
    [BibTex] [Download] 
    @Article{Kemmetmueller15b,
Title = {Optimal torque control of permanent magnet synchronous machines using magnetic equivalent circuits},
Author = {Kemmetm\"uller, W. and Faustner, D. and Kugi, A.},
Journal = {Mechatronics},
Pages = {22--33},
Volume = {32},
Year = {2015},
Doi = {10.1016/j.mechatronics.2015.10.007},
ISSN = {0957-4158},
}
  • W. Kemmetmüller, D. Faustner, and A. Kugi, Modeling of a permanent magnet synchronous machine with internal magnets using magnetic equivalent circuits, IEEE Transactions on Magnetics, vol. 50, iss. 6, 2014.
    [BibTex] [Download] 
    @Article{Kemmetmueller14,
Title = {Modeling of a permanent magnet synchronous machine with internal magnets using magnetic equivalent circuits},
Author = {Kemmetm{\"u}ller, Wolfgang and Faustner, David and Kugi, Andreas},
Journal = {IEEE Transactions on Magnetics},
Volume = {50},
Year = {2014},
Number = {6},
Doi = {10.1109/TMAG.2014.2299238},
}

Project partner