
Udo FreseUniversity of Bremen | Uni Bremen · Faculty 03: Mathematics/Computer Science
Udo Frese
Prof. Dr.-Ing.
Professor for multi-sensor interactive systems at University of Bremen
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131
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Introduction
Publications
Publications (131)
Shared control in assistive robotics blends human autonomy with computer assistance, thus simplifying complex tasks for individuals with physical impairments. This study assesses an adaptive Degrees of Freedom control method specifically tailored for individuals with upper limb impairments. It employs a between-subjects analysis with 24 participant...
User-centered evaluations are a core requirement in the development of new user related technologies. However, it is often difficult to recruit sufficient participants, especially if the target population is small, particularly busy, or in some way restricted in their mobility. We bypassed these problems by conducting studies on trade fairs that we...
Slip, trip, and fall (STF) accidents cause high rates of absence from work in many companies. During the 2022 reporting period, the German Social Accident Insurance recorded 165,420 STF accidents, of which 12 were fatal and 2485 led to disability pensions. Particularly in the traffic, transport and logistics sector, STF accidents are the most frequ...
With the ongoing efforts to empower people with mobility impairments and the increase in technological acceptance by the general public, assistive technologies, such as collaborative robotic arms, are gaining popularity. Yet, their widespread success is limited by usability issues, specifically the disparity between user input and software control...
Shared control in assistive robotics blends human autonomy with computer assistance, thus simplifying complex tasks for individuals with physical impairments. This study assesses an adaptive Degrees of Freedom control method specifically tailored for individuals with upper limb impairments. It employs a between-subjects analysis with 24 participant...
Robotic manipulation requires object pose knowledge for the objects of interest. In order to perform typical household chores, a robot needs to be able to estimate 6D poses for objects such as water glasses or salad bowls. This is especially difficult for glass objects, as for these, depth data are mostly disturbed, and in RGB images, occluded obje...
Accurately acquiring microstructure parameters of porous materials is key to microstructure analysis. Polar ice cores are frozen time capsules holding invaluable information about past climates of our planet in their microstructure. Via micro CT scanning it is possible to capture ice core microstructure parameters, however, scanning the whole firn...
With the ongoing efforts to empower people with mobility impairments and the increase in technological acceptance by the general public, assistive technologies, such as collaborative robotic arms, are gaining popularity. Yet, their widespread success is limited by usability issues, specifically the disparity between user input and software control...
Robotic solutions, in particular robotic arms, are becoming more frequently deployed for close collaboration with humans, for example in manufacturing or domestic care environments. These robotic arms require the user to control several Degrees-of-Freedom (DoFs) to perform tasks, primarily involving grasping and manipulating objects. Standard input...
Robotic solutions, in particular robotic arms, are becoming more frequently deployed for close collaboration with humans, for example in manufacturing or domestic care environments. These robotic arms require the user to control several Degrees-of-Freedom (DoFs) to perform tasks, primarily involving grasping and manipulating objects. Standard input...
Robotic solutions, in particular robotic arms, are becoming more frequently deployed for close collaboration with humans, for example in manufacturing or domestic care environments. These robotic arms require the user to control several Degrees-of-Freedom (DoFs) to perform tasks, primarily involving grasping and manipulating objects. Standard input...
Ice cores of polar regions (ice sheets) are one of the most prominent natural archives that can reveal essential historical information from the past environment of our planet. The ice core microstructure is a key feature in determining the principal properties of ice such as pore close-off, albedo, and melt events. Micro-CT scans can provide valua...
Assistive robotic arms, e.g., the Kinova JACO, aim to assist people with upper-body disabilities in everyday tasks and thus increase their autonomy (Brose et al. 2010; Beaudoin et al.2019). A long-term survey with seven JACO users showed that they were satisfied with the technology and that JACO had a positive psychosocial impact. Still, the users...
Assistive robotic arms, e.g., the Kinova JACO, aim to assist people with upper-body disabilities in everyday tasks and thus increase their autonomy (Brose 2010; Beaudoin 2018}. A long-term survey with seven JACO users showed that they were satisfied with the technology and that JACO had a positive psychosocial impact. Still, the users had some diff...
State estimation can significantly benefit from prior
knowledge about a system’s dynamics and state. In this paper,
we investigate a special class of prior knowledge: Events that
correspond to a subset of the state space. This class of knowledge
was introduced in pedestrian activity classification to improve
the position estimation. We argue that t...
Robot arms are one of many assistive technologies used by people with motor impairments. Assistive robot arms can allow people to perform activities of daily living (ADL) involving grasping and manipulating objects in their environment without the assistance of caregivers. Suitable input devices (e.g., joysticks) mostly have two Degrees of Freedom...
Estimating the pose of an object is essential for robot manipulation. In many applications the spatial and geometric relations between the object and the other parts of the world, e.g. the relation between the object and its supporting plane, are a-priori known or can be assumed with a certain accuracy. This information can be leveraged for pose es...
For some years, inertial sensors have become increasingly popular in various sports applications due to their small size and weight. However–due to the problem of sensor drift–additional sensors are usually required to obtain reliable position estimates. In this paper, we present an approach for position estimation in bouldering that relies solely...
This Article introduces two research projects towards assistive robotic arms for people with severe body impairments. Both projects aim to develop new control and interaction designs to promote accessibility and a better performance for people with functional losses in all four extremities, e.g. due to quadriplegic or multiple sclerosis. The projec...
This paper presents a novel approach to shared control for an assistive robot by adaptively mapping the degrees of freedom (DoFs) for the user to control with a low-dimensional input device. For this, a convolutional neural network interprets camera data of the current situation and outputs a probabilistic description of possible robot motion the u...
Hybrid systems are subject to multiple dynamic models, or so-called modes. To estimate
the state, the sequence of modes has to be estimated, which results in an exponential growth of possible sequences. The most prominent solution to handle this is the interacting multiple model filter, which can be extended to smoothing. In this paper, we derive a...
In this paper we investigate the problems that Convolutional Neural Networks (CNN) based pose estimators have with symmetric objects. We find that the CNN's output representation has to form a closed loop when continuously rotating by one step of symmetry. Otherwise the CNN has to learn an uncontinuous function. On a 1-DOF toy example we show that...
The interacting multiple model filter is the standard in state estimation where different dynamic models are required to model the behavior of a system. It performs a probabilistic mixing of estimates. Up to now, it is undefined how to perform this mixing properly on manifold spaces, e.g. quaternions. We present the proper probabilistic mixing on d...
Control, tracking, and obstacle detection algorithms for mobile robots, including autonomous cars, rely on a jump-free estimate of the vehicle's pose. While one cannot completely avoid jumps in global solutions like INS/GNSS and SLAM, relative localization (i.e., odometry) does not suffer from this problem. Methods based on graph optimization are p...
Inertial navigation systems suffer from unbounded errors in the position and orientation estimates. This drift can be corrected by applying prior knowledge, instead of using exteroceptive sensors. We want to show that the use of prior knowledge can yield full observability of the position and orientation. A previous study showed that track cyclers...
Since underwater systems operate out of immediate reach, often autonomously, for extended periods of time, the correctness of both the software and hardware constituting these systems is of high concern. In this contribution, we review existing techniques to ensure the correctness of hardware and software using formal methods, and assess their appl...
This position paper presents initial thoughts on how some techniques from general robotics can help for autonomous underwater vehicle (AUV) navigation in confined spaces by exploiting in particular the spatial borders and considering information that is not available in open waters. There are natural confined spaces, e.g. caves, as well as artifici...
Image based object recognition and pose estimation is nowadays a heavily focused research field important for robotic object manipulation. Despite the impressive recent success of CNNs to our knowledge none includes a self-estimation of its predicted pose’s uncertainty.
This paper addresses visual navigation of autonomous underwater vehicles (AUVs) with and without a given map, where the latter is called Simultaneous Localization and Mapping (SLAM). We summarize the challenges and opportunities in underwater environments that make visual navigation different from land navigation and also briefly survey the current...
This paper addresses visual navigation of autonomous underwater vehicles (AUVs) with and without a given map, where the latter is called Simultaneous Localization and Mapping (SLAM). We summarize the challenges and opportunities in underwater environments that make visual navigation different from land navigation and also briefly survey the current...
Inertial Navigation Systems suffer from unbounded errors on the position and orientation estimate. This drift can be corrected by applying prior knowledge, instead of using exteroceptive sensors. Analysing the state observability induced by prior knowledge motivates us to track bikers in track cycling races. In this paper, we show that the pose of...
Inertial Navigation Systems suffer from unbounded errors on the position and orientation estimate. Extero-
ceptive sensors may not always be available to correct the error. Applications in the literature overcome this
problem by fusing IMU data with prior knowledge in an ad-hoc fashion. In different applications, various
knowledge is available, whi...
The calibration of cameras is a crucial step in machine vision and usually relies on an accurate detection and localization of calibration patterns in images. Therefore, checker-boards are often used, allowing precise subpixel estimation of their corners. However, noise in localization generates a proportional noise in the derived model parameters....
We show the identification of dynamic parameters for a redundant flexible joint robot with a flexible bearing in the first joint. We compare a standard model (without flexible bearing) and an extended model (with flexible bearing). The bearing leads to distortions of the link velocities measured by gyroscopes. Joint positions measured by encoders....
For both visual analysis and computer assisted diagnosis systems in breast MRI reading, the delineation and diagnosis of ductal carcinoma in situ (DCIS) is among the most challenging tasks. Recent studies show that kinetic features derived from dynamic contrast enhanced MRI (DCE-MRI) are less effective in discriminating malignant non-masses against...
Building a ball playing entertainment robot with the main contribution of a task level optimal control which handles trajectory planning and optimal control in a single controller and takes redundancy and elasticity into account. For faster actuation the feedback gain is used and the controller distributes into two parts. Human-Robot- Interaction(H...
This paper discusses the estimation of the position and orientation, i.e. the pose, of a rigid body and the posture of a human using inertial sensor data only, i.e. without absolute pose information. Since this is impossible in general, specific assumptions as to the rigid body motion and the skeleton’s structure are introduced. What to expect of e...
This paper addresses the problem of calibrating a pair of cameras, a Microsoft Kinect sensor and an inertial measurement unit (IMU) mounted at the head of a humanoid robot with respect to its kinematic chain. As complex manipulation tasks require an accurate interplay of all involved sensors, the quality of calibration is crucial for the outcome of...
The main contribution of this paper is the dimensionality reduction for multiple-step 2D point feature based Simultaneous Localization and Mapping (SLAM), which is an extension of our previous work on one-step SLAM (Wang et al., 2013). It has been proved that SLAM with multiple robot poses and a number of point feature positions as variables is equ...
Vor dem Hintergrund einer alternden Gesellschaft in den meisten europäischen Ländern und einem Fachkräftemangel in vielen technischen Berufen ist ein möglichst langes persönliches Arbeitsleben von essentieller Bedeutung. Insbesondere in Industriezweigen mit hoher körperlicher Belastung sind viele Arbeitnehmer von Krankheiten wie beispielsweise eine...
For such common tasks as motion planning or object recognition robots need to perceive their environment and create a dense 3D map of it. A recent breakthrough in this area was the KinectFusion algorithm [16], which relies on step by step matching a depth image to the map via ICP to recover the sensor pose and updating the map based on that pose. I...
This special issue contains extended versions of the best papers from the 6th European Conference on Mobile Robots (ECMR). ECMR is a biennial European forum, internationally open, that allows roboticists throughout Europe to become acquainted with the latest research accomplishments and innovations in mobile robotics and mobile human–robot systems....
In this paper we propose a physically motivated sensor model of Time-of-Flight cameras. We provide methods to calibrate our proposed model and compensate all modeled effects. This enables us to reliably detect and filter out inconsistent measurements and to record high dynamic range (HDR) images. We believe that HDR images have a significant benefi...
In this paper we introduce an online object manipulation system for the NAO robot that is able to detect and grasp an object out of a human hand and then give it back in real-time. Known objects are rendered from 3D models and detected stereo contour-based by using a new stereo vision head for NAO. In order to grasp objects, motion trajectories are...
In this paper we introduce an online object manipulation system for the NAO robot that is able to detect and grasp an object out of a human hand and then give it back in real-time. Known objects are rendered from 3D models and detected stereo contour-based by using a new stereo vision head for NAO. In order to grasp objects, motion trajectories are...
We developed a task-oriented controller based on optimal finite horizon control. We demonstrate this on a flexible ball playing robot with redundant degrees of freedom. The task is to reach a specified Cartesian position and velocity of the bat at a specified time, in order to rebound the ball. The controller must maintain high accuracy and react t...
This paper presents a minimalistic robot for playing interactive ball games with human players. It is designed with a realistic entertainment application in mind, being safe, flexible, reasonably cheap, and reactive. This is achieved by a clever, minimalistic robot design with a 2 DOF roll tilt unit that moves a bat with a spherical head. The robot...
Without a precise and up-to-date model of its environment a humanoid robot cannot move safely or act usefully. Ideally, the robot should create a dense 3D environment model in real-time, all the time, and respect obstacle information from it in every move it makes as well as obtain the information it needs for fine manipulation with its fingers fro...
This paper proves that the optimization problem of one-step point feature Simultaneous Localization and Mapping (SLAM) is equivalent to a nonlinear optimization problem of a single variable when the associated uncertainties can be described using spherical covariance matrices. Furthermore, it is proven that this optimization problem has at most two...
This paper studies different criteria for selecting
configurations for the task of calibrating a robotic system. Given
an automatic and self-contained procedure which allows the
robot to calibrate itself without the need of external tools, we
are interested in how to select the set of configurations that
maximize calibration accuracy while minimizi...
The Kinect sensor and KinectFusion algorithm have revolutionized environment modeling. We bring these advances to optimization-based motion planning by computing the obstacle and self-collision avoidance objective functions and their gradients directly from the KinectFusion model on the GPU without ever transferring any model to the CPU. Based on t...
We present a method to simultaneously track multiple objects which are subject to physical motion and can be evaluated through raw detector responses in video. Due to their two-staged design, popular tracking-by-detection approaches lack precision in the estimated trajectories due to detector inaccuracies, e.g., lighting, deformation or background...
This paper describes an Extended Kalman Filter for a wheel mounted inertial measurement unit using two accelerometers and a single gyroscope as a substitute for classical odometry sensing. The sensor can be mounted with minimal effort on existing wheeled vehicles. It is highly robust against vibration while rolling on uneven terrain and can cope wi...
We believe it is possible to create the visual subsystem needed for the RoboCup 2050 challenge - a soccer match between humans and robots - within the next decade. In this position paper, we argue, that the basic techniques are available, but the main challenge will be to achieve the necessary robustness. We propose to address this challenge throug...
We present a general real-time continuous collision
detection algorithm for arbitrary systems of moving bodies
connected to each other in a kinematic tree of joints. Here
“joint” as a general term refers to the measured relative motion
between two bodies, which may be physically connected or not.
We provide a basic set of joints covering revolute a...
In this paper we introduce an online grasping system for the Nao robot [1] manufactured by Aldebaran Robotics. The proposed system consists of an object detector and a grasp motion planner. Thereby, known objects are detected by a stereo contour-based object detector and hand motion paths are planned by an A*-based algorithm while avoiding obstacle...
In many areas of experimental science ranging from robotics to psychophysical research, to evaluation of spatial sensor-data and surveying, model fitting is a ubiquitous subproblem. Often it is not the actual scientific goal but rather the “necessary evil” of calibrating the equipment. This tutorial introduces methodology and a library allowing to...
We present the Kinematic Continuous Collision Detection Library (KCCD), a new library for real-time continuous collision detection for humanoid and industrial robots. The C++ library operates on joint state intervals. Such, it does not
only test a single or N intermediate configurations but assures safety of a whole movement. The library uses spher...
Complex manipulation tasks require an accurate interplay of actuation and sensing. This accuracy can only be achieved by calibrating the relevant components beforehand. Typically calibration procedures are time-consuming and often include subsequent calibration steps, involve multiple people and require external tools. In this paper we alleviate th...
Map joining is an efficient strategy for solving feature based SLAM problems. This paper demonstrates that joining of two 2D local maps, formulated as a nonlinear least squares problem has at most two local minima, when the associated uncertainties can be described using spherical covariance matrices. Necessary and sufficient condition for the exis...
When autonomous robots begin to share the human living and working spaces, safety becomes paramount.
It is legally required that the safety of such systems is ensured, e.g. by certification according to relevant standards
such as IEC61508. However, such safety considerations are
usually not addressed in academic robotics. In this paper
we report on...
A ball catching scenario with the mobile humanoid Rollin' Justin is presented. It can catch up to two simultaneously thrown balls with its hands, reaching a catch rate of over 80%. All DOF (degrees of freedom), i.e., the arms, the torso, and the mobile platform, are used for the reaching motion and the system works completely wirelessly using only...