Event Calendar:

November 2014

Mo Tu We Th Fr Sa Su
44 27 28 29 30 31 01 02
45 03 04 05 06 07 08 09
46 10 11 12 13 14 15 16
47 17 18 19 20 21 22 23
48 24 25 26 27 28 29 30

» All Events

Contact

Volker Grabe

E-Mail: volker.grabe[at]gmail.com

 

Picture of Grabe, Volker

Volker Grabe

Position: PhD Student  Unit: Alumni Bülthoff

As of April 2014, I have left the Max Planck Institute for Biological Cybernetics to join Near Earth Autonomy Inc., a vibrant Carnegie Mellon University spin-off in Pittsburgh, PA, USA.

 

During my time as a member of the Autonomous Robotics and Human-Machine Systems Group at the Max Planck Institute for Biological Cybernetics, I have been a Ph.D. student under the co-supervision of Dr. Paolo Robuffo Giordano (IRISA/INRIA Rennes, France) and Prof. Davide Scaramuzza (University of Zurich, Switzerland) between October 2010 and March 2014. My doctoral advisor has been Professor Andreas Schilling (Eberhard Karls Universität Tübingen, Germany).

 

Between November 2012 and March 2014, I was a visiting student with Davide Scaramuzza in his Robotics and Perception Group at the University of Zurich in Switzerland.

 

In the field of vertical take-off and landing vehicles, cameras became the most favored sensors for tracking and localization. However, most systems with a camera as their main sensor usually perform large portions of the computation on a powerful ground station. This clearly limits the flexibility of the system. Additionally, many presented systems lack robust backup strategies to deal with failures of the main tracking system which often relies on a map or given features.

 

In my work, I was addressing these limitations by relying mainly on optical flow and sensor fusion with inertial sensors. Having developed a robust fall-back behavior which allows the vehicle to hover in place if any more advanced system fails, I was then exploiting this work towards active visual guiding with the aim of autonomous avoidance of static as well as moving obstacles.

Please note that the remainder of this page discusses a project conducted at the end of 2011. For an overview of my work until I left the MPI in early 2014, please consult my publication record. In 2012, I was continuing work on visual velocity estimation. Additionally, I was contributing to sensor fusing techniques for IMU and visual information to recover a metric scale. Since spring 2013, I was mostly addressing the problem of distributed sensing, that is, a swarm of heterogeneous robots collaborates in a mapping task by each contributing with different sensors. So far, this involves cameras, RGBD sensors, IMUs, and laser range scanners.

 

Recently, in the field of vertical take-off and landing vehicles, cameras became the most favored sensors for tracking and localization. However, most systems with a camera as their main sensor usually perform large portions of the computation on a powerful ground station. This clearly limits the flexibility of the system. Additionally, many presented systems lack robust backup strategies to deal with failures of the main tracking system which often relies on a map or given features.

 

In this project, we are aiming at developing a robust system which is able to visually estimate its velocity using the optical flow obtained from a monocular camera and thus without the need to maintain a map. All computation will be done on-board the vehicle itself with only the velocity commands being transmitted to the quadrotor. Sensor fusion with an additional IMU (Inertial Measurement Unit) will be done to retrieve the scale and improve the velocity estimation.

 

Quadrotor with IMU and down-facing camera highlighted.

Our work will be carried out on quadrotors manufactured from MikroKopter.de equipped with a small Intel Atom 1.6 GHz board. The final setup is shown in Figure 1. Image processing and optical flow extraction are based on the OpenCV library. To estimate the velocity, we use a customized version of the continuous four-point algorithm for planar scenes.

 

 

 

 

 

Linear velocity in x dimension as estimated by our algorithm (filtered and unfiltered) in comparison with the ground truth during a closed-loop control experiment.

Figure 2 presents a comparison between the linear velocity estimated by our algorithm and the ground truth obtained from a Vicon tracking system during closed-loop control. This comparison demonstrates reliable velocity estimation with a mean error of only 0.028 m/s.

 

Our results show clearly that it is indeed possible to stabilize a quadrotor in closed-loop control using our algorithm on the limited hardware described. Thus, our system can be used as a robust emergency stopping behavior which does not require any knowledge of the environment (e.g. a map).

Current Position

Research Scientist
Near Earth Autonomy Inc.
Pittsburgh, PA, USA

 

Educational Background

2012-2014

Visting Ph.D. Student
supervised by Prof. Davide Scramauzza
Robotics and Perception Group, University of Zurich, Switzerland

2010-2014 Ph.D. Student
supervised by Dr. Paolo Robuffo Giordano
Department Human Perception, Cognition and Action (Dept.Head: Heinrich H. Buelthoff), Max Planck Institute for Biological Cybernetics, Tübingen, Germany
2010 Diplomarbeit (Master thesis)
supervised by Dr. Paolo Robuffo Giordano
Department Human Perception, Cognition and Action (Dept.Head: Heinrich H. Buelthoff), Max Planck Institute for Biological Cybernetics, Tübingen, Germany
Thesis Title: Wide Field of View Head Mounted Display: Integration and Evaluation in a Motion Simulator
2007-2008 Graduate studies in Bioinformatics,
Project work with Jeffery Blanchard
University of Massachusetts, Amherst, USA
2004-2010 Diplom-Informatiker/Bioinformatiker (German M.Sc. Computer Science/Bioinformatics)
Eberhard Karls Universität Tübingen, Germany
2004 Abitur
Gymnasium Harksheide, Norderstedt, Germany

 

References, etc.

References are available upon request.

Preferences: 
References per page: Year: Medium:

  
Show abstracts

Articles (1):

Franchi A Person, Masone C Person, Grabe V Person, Ryll M Person, Bülthoff HH Person and Robuffo Giordano P Person (October-2012) Modeling and Control of UAV Bearing-Formations with Bilateral High-Level Steering International Journal of Robotics Research 31(12) 1504-1525.
pdf

Conference papers (5):

Grabe V Person, Bülthoff HH Person and Robuffo Giordano P Person (November-2013) A comparison of scale estimation schemes for a quadrotor UAV based on optical flow and IMU measurements IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2013), IEEE, Piscataway, NJ, USA, 5193-5200.
pdf
Grabe V Person, Riedel M Person, Bülthoff HH Person, Robuffo Giordano P Person and Franchi A Person (September-2013) The TeleKyb Framework for a Modular and Extendible ROS-based Quadrotor Control 6th European Conference on Mobile Robots (ECMR 2013), IEEE, Piscataway, NJ, USA, 19-25.
pdf
Grabe V Person, Bülthoff HH Person and Robuffo Giordano P Person (October-2012) Robust Optical-Flow Based Self-Motion Estimation for a Quadrotor UAV IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2012), IEEE, Piscataway, NJ, USA, 2153-2159.
pdf
Grabe V Person, Bülthoff HH Person and Robuffo Giordano P Person (May-2012) On-board velocity estimation and closed-loop control of a quadrotor UAV based on optical flow IEEE International Conference on Robotics and Automation (ICRA 2012), IEEE, Piscataway, NJ, USA, 491-497.
pdf
Grabe V Person, Pretto P Person, Robuffo Giordano P Person and Bülthoff HH Person (September-2010) Influence of display type and field of view on drivers’ performance in a motion-based driving simulator In: Trends in driving simulation design and experiments, Driving Simulation Conference Europe (DSC 2010), INRETS, Bron, France, 81-88.
pdf

Theses (2):

Grabe V Person: Towards Robust Visual-Controlled Flight of Single and Multiple UAVs in GPS-Denied Indoor Environments, Eberhard-Karls-Universität Tübingen, Germany, (March-2014). PhD thesis
Grabe V Person: Wide Field of View Head Mounted Display: Integration and Evaluation in a Motion Simulator, Eberhards-Karls-Universität Tübingen, Germany, (June-1-2010). Diplom thesis
pdf

Export as:
BibTeX, XML, Pubman, Edoc, RTF
Last updated: Tuesday, 18.11.2014