Anders Stengaard Sørensen

Real-time medical video processing, enabled by hardware accelerated correlations

Image processing involving correlation based filter algorithms have proved extremely useful for image enhancement, feature extraction and recognition, in a wide range of medical applications, but is almost exclusively used with still images due to the amount of computations required by the correlations. In this paper, we present two different practical methods for applying correlation-based algorithms to real-time video images, using hardware accelerated correlation, as well as our results in applying the method to optical venography. The first method employs a GPU accelerated personal computer, while the second method employs an embedded FPGA. We will discuss major difference between the two approaches, and their suitability for clinical use. The system presented detects blood vessels in human forearms in images from NIR camera setup for the use in a clinical environment.

Adherence to Commonly Prescribed, Home-based Strength Training Exercises for the Lower Extremity Can Be Objectively Monitored Using the Bandcizer

Abstract Rathleff, MS, Thorborg, K, Rode, LA, McGirr, KA, Sørensen, AS, Bøgild, A, and Bandholm, T. Adherence to commonly prescribed, home-based strength training exercises for the lower extremity can be objectively monitored using the Bandcizer. J Strength Cond Res 29(3): 627–636, 2015—The purpose of this study was to investigate the validity of automatically stored exercise data from the elastic band sensor compared with those of a gold-standard stretch sensor during exercises commonly used for rehabilitation of the hip and knee. The design was a concurrent validity study. Participants performed 3 sets of 10 repetitions of 6 exercises with both sensors attached to the same elastic exercise band. These were knee extension, knee flexion, hip abduction and adduction, hip flexion, and hip external rotation. Agreement between methods was calculated for date, time of day, repetitions, total and single repetition, and contraction phase–specific time under tension (TUT). Files from the elastic band sensor contained identical dates, time of day, and number of repetitions for each exercise set compared with those for the gold standard. Total TUT and total single repetition TUT were highly correlated with the stretch sensor (r = 0.83–0.96) but lower for contraction phase–specific TUTs (r = 0.45–0.94). There were systematic differences between the methods ranging from 0.0 to 2.2 seconds (0.0–6.3%) for total TUT and total single repetition TUT, and between 0.0 and 3.3 seconds (0.0–33.3%) for contraction phase–specific TUTs. The elastic band sensor is a valid measure of date, time of day, number of repetitions and sets, total TUT, and total single repetition TUT during commonly used home-based strength training exercises. However, the elastic band sensor seems unable to validly measure TUT for specific contraction phases.

A Real-Time Embedded System for Stereo Vision Preprocessing Using an FPGA

In this paper a low level vision processing node for use in existing IEEE 1394 camera setups is presented. The processing node is a small embedded system, that utilizes an FPGA to perform stereo vision preprocessing at rates limited by the bandwidth of IEEE 1394a (400 Mbit). The system is used in a hybrid architecture [5], where it produces undistorted and rectified 512 x 512 images at 2 x 15 frames pr. second (fps) as either a downsampled version or a region of interest (ROI) of the high resolution camera output. Three processes are performed: Bayer demosaicing, downsampling and region of interest extraction, and undistortion and rectification. The latency of the system when running at 2 x 15 fps is 30 ms.

New exercise-integrated technology can monitor the dosage and quality of exercise performed against an elastic resistance band by adolescents with patellofemoral pain: an observational study

QUESTION Is the exercise-integrated Bandcizer™ system feasible for recording exercise dosage (time under tension (TUT) and repetitions) and pain scores among adolescents with patellofemoral pain? Do adolescents practise the exercises as prescribed (TUT and repetitions)? Do adolescents accurately report the exercises they do in an exercise diary? DESIGN Observational feasibility study. PARTICIPANTS Twenty adolescents between 15 and 19 years of age with patellofemoral pain. INTERVENTION Participants were prescribed three exercise sessions per week (one with and two without supervision) for 6 weeks. The exercises included three hip and one knee exercise with an elastic resistance band. Participants were instructed to perform three sets with a predefined TUT (3seconds concentric; 2seconds isometric; 3seconds eccentric; 2seconds pause), equating to 80seconds for 10 repetitions (one set). OUTCOME MEASURES The exercise-integrated system consisted of a sensor attached to the elastic resistance band that was connected to the Bandtrainer app on an electronic tablet device. Pain intensity was reported on a visual analogue scale on the app. Participants also completed a self-report exercise diary. RESULTS No major problems were reported with the system. Participants performed 2541 exercise sets during the 6 weeks; 5% were performed with the predefined TUT (ie, within 10seconds of the 80-second target) and 90% were performed below the target TUT. On average, the participants received 15% of the instructed exercise dosage based on TUT. The exercise dosage reported in the exercise diaries was 2.3 times higher than the TUT data from the electronic system. Pain intensity was successfully collected in 100% of the exercise sets. CONCLUSION The system was feasible for adolescents with patellofemoral pain. The system made it possible to capture detailed data about the TUT, repetitions and sets during home-based exercises together with pain intensity before and after each exercise. [Rathleff MS, Bandholm T, McGirr KA, Harring SI, Sørensen AS, Thorborg K (2016) New exercise-integrated technology can monitor the dosage and quality of exercise performed against an elastic resistance band by adolescents with patellofemoral pain: an observational study.Journal of Physiotherapy62: 159-163].

A System on Chip approach to enhanced learning in interdisciplinary robotics

To sustain advanced interdisciplinary teaching and learning in the rapidly growing and diversifying field of robotics, we have successfully employed FPGA based System on Chip (SoC) technology to provide abstraction between high level software and low level I/O- and control hardware. Our approach is to provides students with a simple FPGA based framework for hardware access, and hardware I/O development, which is independent of computer platform and programming language, and enable the students to add to, or change I/O hardware in accordance with their skills. We have tested the framework in an embedded systems course and various student projects, and have found that it greatly enhance the students abilities to control hardware from software, and dramatically reduce the time spent on software ↔ hardware interfacing. As the framework is also scalable, it can support projects from controlling a single LED, to complex modular and aggregated robots with demands for high bandwidths and low jitter in the control loop.

HartOS - A hardware implemented RTOS for hard real-time applications

This paper introduces HartOS, a hardware-implemented, micro-kernel-structured RTOS targeted for hard real-time embedded applications running on FPGA based platforms. Historically hardware RTOSs have been too inflexible and have had limited features and resources. HartOS is designed to be flexible and supports most of the features normally found in a software-based RTOS. To ensure fast, low latency and jitter-free communication between the CPU and RTOS, HartOS uses the ARM AXI4-Stream bus recently supported by the MicroBlaze softcore processor. Compared to μC/OS-II, HartOS has up to 3 orders of magnitude less mean error in generating the correct period for a periodic task, and around 1 order of magnitude less jitter, while having up to 100% less overhead depending on the tick frequency.

Low-cost modular robotic system for neurological rehabilitative training

This paper presents the concept, development and testing of RoboTrainer-Light, a low-cost yet effective and usable training robot designed for use in the home. Although designed for simplicity and economic mass production, it is believed to enable a large section of patients with partial paralysis to perform effective neurological training in their own home. The robot consists of a wire-pulling motor combined with a sensitive force sensor, controlled by an ultra-high-bandwidth hybrid controller, allowing any combination of tension-, velocity- and length-control of the wire. The controller architecture is distributed and modular, allowing up to 15 wire pulling motors to be combined in parallel kinematic configurations. Compared to other rehabilitative robots, RoboTrainer-Light represents one of the simplest and cheapest possible configurations, which is further emphasized by our deliberate choice of low-cost components and technologies. Preliminary tests indicate that RoboTrainer-Light can support a large group of post-stroke and post-accident victims in effective neurological training in their own home or in local clinics, at an estimated cost lower than 500USD per unit for a high production volume.

Towards using a generic robot as training partner: off-the-shelf robots as a platform for flexible and affordable rehabilitation

In this paper, we demonstrate how a generic industrial robot can be used as a training partner, for upper limb training. The motion path and human/robot interaction of a nongeneric upper-arm training robot is transferred to a generic industrial robot arm, and we demonstrate that the robot arm can implement the same type of interaction, but can expand the training regime to include both upper arm and shoulder training. We compare the generic robot to two affordable but custom-built training robots, and outline interesting directions for future work based on these training robots.

Kinesthetic human/robot coordination: the coordination of movements for interaction

Training with a robotic training partner, is a physical, powerful, and yet intimate form of robot/human interaction (RHI). In this paper we report on the early stages of a project, that aims to study and use the human kinesthetic “language” of co-motion, used in physical human/robot interaction such as training.

RoBlock: a prototype autonomous manufacturing cell

RoBlock is the first phase of an internally financed project at the Institute aimed at building a system in which two industrial robots suspended from a gantry, as shown below, cooperate to perform a task specified by an external user, in this case, assembling an unstructured collection of colored wooden blocks into a specified 3D pattern. The blocks are identified and localized using computer vision and grasped with a suction cup mechanism. Future phases of the project will involve other processes such as grasping and lifting, as well as other types of robot such as autonomous vehicles or variable geometry trusses. Innovative features of the control software system include: The use of an advanced trajectory planning system which ensures collision avoidance based on a generalization of the method of artificial potential fields, the use of a generic model-based controller which learns the values of parameters, including static and kinetic friction, of a detailed mechanical model of itself by comparing actual with planned movements, the use of fast, flexible, and robust pattern recognition and 3D-interpretation strategies, integration of trajectory planning and control with the sensor systems in a distributed Java application running on a network of PCs attached to the individual physical components. In designing this first stage, the aim was to build in the minimum complexity necessary to make the system non-trivially autonomous and to minimize the technological risks. The aims of this project, which is planned to be operational during 2000, are as follows: To provide a platform for carrying out experimental research in multi-agent systems and autonomous manufacturing systems, to test the interdisciplinary cooperation architecture of the Maersk Institute, in which researchers in the fields of applied mathematics (modeling the physical world), software engineering (modeling the system) and sensor/actuator technology (relating the virtual and real worlds) could collaborate with systems integrators to construct intelligent, autonomous systems, and to provide a showpiece demonstrator in the entrance hall of the Institutes new building.