Visual Feedback System Research Articles

Multi-sensor control for precise assembly of optical components

In order to perform an optical assembly accurately, a multi-sensor control strategy is developed which includes an attitude measurement system, a vision system, a loss measurement system and a force sensor. A 3-DOF attitude measuring method using linear variable differential transformers (LVDT) is designed to adjust the relation of position and attitude between the spherical mirror and the resonator. A micro vision feedback system is set up to extract the light beam and the diaphragm, which can achieve the coarse positioning of the spherical mirror in the optical assembly process. A rapid self-correlation method is presented to analyze the spectrum signal for the fine positioning. In order to prevent the damage of the optical components and realize sealing of the resonator, a hybrid force-position control is constructed to control the contact force of the optical components. The experimental results show that the proposed multi-sensor control strategy succeeds in accomplishing the precise assembly of the optical components, which consists of parallel adjustment, macro coarse adjustment, macro approach, micro fine adjustment, micro approach and optical contact. Therefore, the results validate the multi-sensor control strategy.

Stabilizing Predictive Visual Feedback Control via Image Space Navigation Function

SUMMARYThis paper investigates stabilizing receding horizon control via an image space navigation function for three‐dimensional (3D) visual feedback systems. First, we describe the representation of a relative pose and a camera model. Next, a visual motion error system which can handle time‐varying desired motion is constructed. Then, visual motion observer‐based stabilizing receding horizon control for 3D visual feedback systems is proposed. Moreover, a path planner appropriate for the visual motion error system is designed through an image space navigation function to keep all features in the camera field of view. The main contribution of this paper is to show that the path planner which always remains in the camera field of view during servoing is designed for position‐based visual feedback receding horizon control based on optimal control theory. Finally, we present simulation and nonlinear experimental results in order to verify control performance with visibility maintenance of the proposed control scheme. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(10): 12–21, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11493

Cardiopulmonary performance testing using a robotics-assisted tilt table: feasibility assessment in able bodied subjects

Purpose: Robotics-assisted tilt table technology with integrated leg drives for basic stepping functionality is clinically available for patients with neurological impairments. Initially introduced for early rehabilitation, it provides cyclical stepping movement and physiological loading in immobilized patients. This technology provides stability and support in patients with neurological disorders for whom weakness, balance and coordination problems would preclude cardiopulmonary performance testing using a treadmill or cycle ergometer. This type of device may facilitate the estimation of peak oxygen uptake and other important cardiopulmonary performance parameters in patients who have neurological deficits. The aim of the present study was to assess the feasibility and safety of this device for peak cardiopulmonary performance testing in able-bodied subjects. Methods: A robotics-assisted tilt table (Erigo, Hocoma AG, Switzerland) was augmented with force sensors in the thigh cuffs and a work rate estimation algorithm. A custom visual feedback system was employed to guide the subjects' work rate and to provide real time feedback of actual work rate. Each subject carried out an incremental exercise test to the limit of functional capacity with a work rate increment of 5 W/minute in female subjects and 8 W/minute in males. Outcome measures were peak oxygen uptake (VO2peak), peak heart rate (HRpeak), respiratory exchange ratio (RER), peak work rate (WRpeak) and the Borg CR10 scale to measure exertion and leg fatigue. Results: 11 able-bodied subjects were included (9 male, 2 female; age 29.6±7.1 years: mean ± SD). Resting VO2 was 4.6±0.7 ml/kg/min and VO2peak was 32.4±5.1 ml/kg/min. All participants reached at least 85% of their predicted HRmax value. RER at peak VO2 was 1.02±0.07. Eight participants (72.7%) reached their peak VO2 in 8-12 minutes, which is considered the optimal duration. The average WRpeak was 65.7 W for males and 41.5 W for females. All participants reported a Borg CR10 value for exertion and leg fatigue of 7 or more. There were no serious adverse events. Conclusions: The robotics-assisted tilt table augmented with work rate estimation and a visual feedback system is a feasible and safe method for peak cardiopulmonary performance testing in able-bodied subjects. Future work will evaluate test-retest reliability and compare peak cardiorespiratory performance values with those obtained from a treadmill and a cycle ergometer. The approach will then be piloted in subjects with neurological impairments.

CALL Visual Feedback for Pronunciation of Vowels

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2A1-N01 Study on Visual Feedback Control of Optogenetic Muscle-Powered Bioactuator(マイクロロボット・マイクロマシン)

In our study, we used the dorsal vessel (DV, heart-like tissue) of Drosophila melanogaster (Dmel, fruit fly) larva as a bioactuator. This paper reports on the closed loop visual feedback system to control the contraction rates of the DV in vivo. We investigated the response of the DVs that express channelrhodopsin(ChR2) and/or halorhodopsin(NpHR) to blue and red light. We found that DV expressing ChR2 increased contraction rates under blue light stimulation, while DV expressing NpHR stopped contracting under red light stimulation. In our feedback experiments, we managed to keep the contraction frequency of the DV in vivo above an arbitrary threshold value using the visual feedback system we developed.

Development of 3D Visual Feedback System for Cybernic Master System

This paper developed 3D Visual Feedback System for Cybernic Master System. This Cybernic master system is a master-slave system for manipulations and consists of master-slave robot arm and visual feedback system. The Cybernic master arm uses joint torque estimation method, based on Bioelectrical Signal. To reap full advantage of the control method, not only feedback to somatosensory system such as force and impedance control but also optimal visual feedback is an important factor in transmitting information to an operator. To achieve visual feedback, it is installed stereoscopic vision and operation assist system using Augmented Reality. The stereoscopic vision is controlled by our active control method of a convergence angle depending on the distance to objects. The operation assist system can show stereoscopic images that is overlaid the virtual objects. Using the virtual objects such as virtual walls and protected areas, it is possible to assist the safe operations. We conducted experiments to verify that the operator can view parallax image stereoscopically at the leaching range that is near to a human arm. Our system in short distance was effective compared with normal parallax method. Then, we conducted operation test to ensure that it is possible to perform the area protection with the virtual wall using our system. At the result, protection areas were formed, and we ensured that slave arm robot could not invade those areas. In addition, the operation assists such as not only protection of crash but also the tracing movement and operation instruction by the virtual walls is possible.

Use of Backboard and Deflation Improve Quality of Chest Compression When Cardiopulmonary Resuscitation Is Performed on a Typical Air Inflated Mattress Configuration

No study has examined the effectiveness of backboards and air deflation for achieving adequate chest compression (CC) depth on air mattresses with the typical configurations seen in intensive care units. To determine this efficacy, we measured mattress compression depth (MCD, mm) on these surfaces using dual accelerometers. Eight cardiopulmonary resuscitation providers performed CCs on manikins lying on 4 different surfaces using a visual feedback system. The surfaces were as follows: A, a bed frame; B, a deflated air mattress placed on top of a foam mattress laid on a bed frame; C, a typical air mattress configuration with an inflated air mattress placed on a foam mattress laid on a bed frame; and D, C with a backboard. Deflation of the air mattress decreased MCD significantly (B; 14.74 ± 1.36 vs C; 30.16 ± 3.96, P < 0.001). The use of a backboard also decreased MCD (C; 30.16 ± 3.96 vs D; 25.46 ± 2.89, P = 0.002). However, deflation of the air mattress decreased MCD more than use of a backboard (B; 14.74 ± 1.36 vs D; 25.46 ± 2.89, P = 0.002). The use of a both a backboard and a deflated air mattress in this configuration reduces MCD and thus helps achieve accurate CC depth during cardiopulmonary resuscitation.

Accurate Measurement of Head Related Transfer Function Based on Visual Feedback System

Accurate Measurement of Head Related Transfer Function Based on Visual Feedback System

Evaluation of Construction Robot Telegrasping Force Perception Using Visual, Auditory and Force Feedback Integration

Construction robot telegrasping operation provides considerable challenges in postdisaster recovery missions. This paper presents an evaluation of construction robot telegrasping force perception, which integrates the use of visual, auditory and force feedback systems. The integration of graphically-presented feedback force is proposed to help operators visually monitor changes in grasping force. Auditory feedback is used simultaneously to provide rapid warnings, while force feedback enhances grasping sense. Sensitivity to each type of feedback is measured by using psychophysical tests, and manipulation tests are conducted to observe effects on the gripping risk index, task completion time and subjective workload. Results validate the need for multimodal sensory feedback, for accurately controlling the grasping process, and for avoiding unnecessary action due to human error.

The Role of Visual Feedback and Creative Exploration for the Improvement of Timing Accuracy in Performing Musical Ornaments

in developing a visual feedback system for a creative activity such as music performance, the objective is not just to reinforce one particular manner of performing. Instead, a desirable characteristic might be that the visual feedback enhances flexibility and originality, in addition to contributing to performance precision. In an experimental study focused on the timing of a musical ornament, we examined whether the instruction to explore ornament timing in training trials with or without visual feedback leads to improved temporal precision in imitating target performances of the ornament, and whether visual feedback enhances the performance diversity during training. The study uncovered distinct strategies of exploration of the performance of the musical ornament and highlighted the dynamics of exploration behavior during training. Visual feedback enhanced exploration of temporal characteristics and influenced imitation accuracy. This study opens up educational possibilities for the training of performance skills and provides direction for further investigation of creative processes in performance.

Visual feedback system to reduce errors while operating roof bolting machines

ProblemOperators of roof bolting machines in underground coal mines do so in confined spaces and in very close proximity to the moving equipment. Errors in the operation of these machines can have serious consequences, and the design of the equipment interface has a critical role in reducing the probability of such errors. MethodsAn experiment was conducted to explore coding and directional compatibility on actual roof bolting equipment and to determine the feasibility of a visual feedback system to alert operators of critical movements and to also alert other workers in close proximity to the equipment to the pending movement of the machine. The quantitative results of the study confirmed the potential for both selection errors and direction errors to be made, particularly during training. ResultsSubjective data confirmed a potential benefit of providing visual feedback of the intended operations and movements of the equipment. ImpactThis research may influence the design of these and other similar control systems to provide evidence for the use of warning systems to improve operator situational awareness.

Vestibular rehabilitation using the Nintendo® Wii Balance Board – a user-friendly alternative for central nervous compensation

Conclusion: The Nintendo® Wii Balance Board is a cost-effective and user-friendly alternative to other popular frequently used systems that aid vestibular compensation, particularly in elderly patients. In addition, further treatment in the home environment is possible. Objective: This cohort study was designed to investigate the impact of the Nintendo® Wii Balance Board as a visual compensation device after acute vestibular neuritis. Methods: Subjects were randomly assigned to one of two treatment groups. Group A (n = 37) performed customized exercises with the Nintendo® Wii Balance Board. Group B (n = 34) performed only two elected exercises as a control group for comparison of the results. Both groups underwent additive therapy with steroids (intravenous) in decreasing doses (250 mg decreasing to 25 mg over 10 days). The Sensory Organization Test (SOT), Dizziness Handicap Inventory (DHI), Vertigo Symptom Scale (VSS), and Tinneti questionnaire were evaluated immediately before treatment (baseline), at the end of treatment, i.e. at day 5, and after 10 weeks. Results: The early use of a visual feedback system in the context of the balance training supports the central nervous vestibular compensation after peripheral labyrinthine disorders. Patients in group B (without training) required a longer in-patient stay (average 2.4 days, SD 0.4) compared with patients following early Wii rehabilitation. The absence of nystagmus under Frenzel's goggles in group A was observed 2.1 days (SD 0.5) earlier than in group B. Group A showed significantly better results in the SOT, DHI, VSS, and Tinneti questionnaire at all time points measured (p < 0.05).

REAL-TIME CAMERA GUIDANCE FOR 3D SCENE RECONSTRUCTION

Abstract. We propose a framework for operator guidance during the image acquisition process for reliable multi-view stereo reconstruction. Goal is to achieve full coverage of the object and sufficient overlap. Multi-view stereo is a commonly used method to reconstruct both camera trajectory and 3D object shape. After determining an initial solution, a globally optimal reconstruction is usually obtained by executing a bundle adjustment involving all images. Acquiring suitable images, however, still requires an experienced operator to ensure accuracy and completeness of the final solution. We propose an interactive framework for guiding unexperienced users or possibly an autonomous robot. Using approximate camera orientations and object points we estimate point uncertainties within a sliding bundle adjustment and suggest appropriate camera movements. A visual feedback system communicates the decisions to the user in an intuitive way. We demonstrate the suitability of our system with a virtual image acquisition simulation as well as in real-world scenarios. We show that when following the camera movements suggested by our system, the proposed framework is able to generate good approximate values for the bundle adjustment, leading to accurate results compared to ground truth after few iterations. Possible applications are non-professional 3D acquisition systems on low-cost platforms like mobile phones, autonomously navigating robots as well as online flight planning of unmanned aerial vehicles.

Evaluation of a visual feedback system in gait retraining: A pilot study

Abnormal gait pattern of the frontal plane (i.e. Duchenne gait and Trendelenburg gait) may be caused by a variety of diseases. The aim of this pilot study was to evaluate the instantaneous effect of a visual feedback system on frontal plane pelvis and trunk movements in order to use it in patients with THR in subsequent studies. A total of 24 women (45–65 years) were included in the study. According to acute functional impairments the subjects were assigned to the control group (CG, no gait disorders, n=15, age=59±11 years, BMI=27±4) or to the intervention group (IG, n=9, age=61±4, BMI=29±5), respectively. First, in Measurement 1 (M1) kinematic reference values were captured in a standardized clinical gait analysis (MVN, XSens). Afterwards, the influence of a visual real-time feedback on gait pattern was examined while using the feedback system (M2). While there was a significant difference of IG vs. CG in M1 in the mean inclination regarding pelvis and trunk movements, this was not detected in M2. Therefore it is concluded, especially in subjects with abnormal gait pattern, that the visualization leads to an improvement of the movement pattern of pelvis and trunk in the frontal plane while using the device.

HEADSET VISUAL FEEDBACK SYSTEM

A visual feedback system (101) that activates a visual display (102) when the sound pressure level from a headset (105) attached to the system exceeds a preset level is provided, along with a method of using the same. The visual feedback system is interposed between the audio source (103) and the headset (105) and is either integral to a specific headset or coupleable to any of a variety of headsets. If a non-integral headset is used with the visual feedback system, the system is matched to the characteristics of the selected headset, for example using a selector switch or via a calibration process. During operation, the visual feedback system illuminates a display (e.g., an LED) whenever the sound pressure level from the attached headset exceeds the preset level. The visual feedback system can be implemented using analog or digital circuitry.

Visual Feedback PID Control for 2DOF Parallel Link Manipulator

This paper investigates the visual feedback control for 2DOF(degrees of freedom) parallel link manipulator with zero steady-state error. Firstly we present the model of visual feedback system of the eye-in-hand configuration. Secondly we consider a novel desired joint angle defined by visual information and joint angles based on the structure of the parallel link, because a desired joint angle cannot be given as a standard robot motion control system. Next we propose the PID control law for the visual feedback system in order to overcome steady-state error with respect to the uncertainty of the position and the orientation for the base frame. For the proposed control law, stability analysis of the closed loop system is discussed in the sense of Lyapunov method with a sufficient condition for the feedback gains. Finally the experimental results are shown in order to confirm the validity of the proposed method by comparing with a previous visual feedback control law.

Stabilizing Predictive Visual Feedback Control via Image Space Navigation Function

SUMMARY This paper investigates stabilizing receding horizon control via an image space navigation function for three-dimensional (3D) visual feedback systems. First, we describe the representation of a relative pose and a camera model. Next, a visual motion error system which can handle time-varying desired motion is constructed. Then, visual motion observer-based stabilizing receding horizon control for 3D visual feedback systems is proposed. Moreover, a path planner appropriate for the visual motion error system is designed through an image space navigation function to keep all features in the camera field of view. The main contribution of this paper is to show that the path planner which always remains in the camera field of view during servoing is designed for position-based visual feedback receding horizon control based on optimal control theory. Finally, we present simulation and nonlinear experimental results in order to verify control performance with visibility maintenance of the proposed control scheme. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(10): 12–21, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11493

Development of Visual Feedback System Based on the Load on Handrails

Development of Visual Feedback System Based on the Load on Handrails

Entrenador virtual para el aprendizaje de rutinas motoras, en personas con ausencia de un miembro superior

El proyecto de investigación en el campo de las ayudas aumentativas para discapacitados, tiene como objetivo principal evaluar el aprendizaje de rutinas motoras en una persona con amputación traumática a nivel del tercio distal del codo por medio de un entrenador virtual controlado por señales mioeléctricas. Este tema de investigación es de gran importancia porque prepara a la persona para el uso de una prótesis real y porque a nivel cognitivo, el entrenador puede crear un sistema de auto-representación que se convierte en un punto de convergencia en el sistema de retroalimentación visual y propioceptiva. Además, debido a la relación de manipulación — identificación— transformación de objetos, ofrece al cerebro nuevos modos de aproximarse a tareas anteriores y la posibilidad de emprender otras nuevas. Para esta investigación se diseñó, elaboró y validó el sistema de captura y reconocimiento de las señales mioeléctricas y el modelo de aprendizaje por observación propuesto inicialmente

Stabilizing predictive visual feedback control for fixed camera systems

AbstractThis paper investigates vision‐based robot control via a receding horizon control strategy for fixed camera systems, as stabilizing predictive visual feedback control. First, a visual motion robot error system with a fixed camera configuration is reconstructed in order to improve estimation performance. Next, stabilizing receding horizon control for three‐dimensional visual feedback systems, which are highly nonlinear and relatively fast systems, is proposed. The stability of the receding horizon control scheme is guaranteed by using a terminal cost derived from an energy function of the visual motion robot error system. Furthermore, simulation and actual nonlinear experimental results are assessed with respect to stability and performance. © 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(8): 1–11, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10357