Workload Assessment in Field Using the Ambulatory CUELA System

Ellegast, Rolf; Hermanns, Ingo; Schiefer, Christoph

doi:10.1007/978-3-642-02809-0_24

Cited by 35 publications

(29 citation statements)

References 8 publications

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“…The IMUs used are part of the new generation of the CUELA system (CUELA, IFA, Sankt Augustin, Germany [1]). They consist of L3GD20 threeaxis gyroscopes and LSM303DLM, three-axis accelerometers and three-axis magnetometers (STMicroelectronics, Geneva, Switzer land).…”

Section: Measurement Systems and Setupmentioning

confidence: 99%

“…In ergonomic workplace eval uation, inertial sensors are used for ambulatory assessment of physical workloads in the field [ 1 ] approach for orientation estimation is that of integrating the angu lar rate information of the gyroscope [2] while the acceleration and magnetic field information are used to compensate orientation drift, caused by integration of small bias errors in the angular rate. In the vicinity of ferromagnetic materials, the magnetic field becomes distorted resulting in an unpredictable orientation error [3], Algorithms using magnetometer information need to identify magnetic field disturbances by analyzing magnetic flux and mag netic inclination [4,5].…”

Section: Introductionmentioning

confidence: 99%

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Optimization of Inertial Sensor-Based Motion Capturing for Magnetically Distorted Field Applications

Schiefer

Ellegast

Hermanns

et al. 2014

Journal of Biomechanical Engineering

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Inertial measurement units (IMU) are gaining increasing importance for human motion tracking in a large variety of applications. IMUs consist of gyroscopes, accelerometers, and magnetometers which provide angular rate, acceleration, and magnetic field information, respectively. In scenarios with a permanently distorted magnetic field, orientation estimation algorithms revert to using only angular rate and acceleration information. The result is an increasing drift error of the heading information. This article describes a method to compensate the orientation drift of IMUs using angular rate and acceleration readings in a quaternion-based algorithm. Zero points (ZP) were introduced, which provide additional heading and gyroscope bias information and were combined with bidirectional orientation computation. The necessary frequency of ZPs to achieve an acceptable error level is derived in this article. In a laboratory environment the method and the effect of varying interval length between ZPs was evaluated. Eight subjects were equipped with seven IMUs at trunk, head and upper extremities. They performed a predefined course of box handling for 40 min at different motion speeds and ranges of motion. The orientation estimation was compared to an optical motion tracking system. The resulting mean root mean squared error (RMSE) of all measurements ranged from 1.7 deg to 7.6 deg (roll and pitch) and from 3.5 deg to 15.0 deg (heading) depending on the measured segment, at a mean interval-length of 1.1 min between two ZPs without magnetometer usage. The 95% limits of agreement (LOA) ranged in best case from -2.9 deg to 3.6 deg at the hip roll angle and in worst case from -19.3 deg to 18.9 deg at the forearm heading angle. This study demonstrates that combining ZPs and bidirectional computation can reduce orientation error of IMUs in environments with magnetic field distortion.

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Section: Measurement Systems and Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimization of Inertial Sensor-Based Motion Capturing for Magnetically Distorted Field Applications

Schiefer

Ellegast

Hermanns

et al. 2014

Journal of Biomechanical Engineering

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“…The sensors were attached and secured on top of the participants' clothing (Ellegast, Hermanns, and Schiefer 2009). For the listed body components, the following postures and corresponding degrees of freedom were determined:…”

Section: Kinematicsmentioning

confidence: 99%

Comparison of the postural and physiological effects of two dynamic workstations to conventional sitting and standing workstations

et al. 2015

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Increasing evidence is being found for the association of health risk factors with work-related physical inactivity. An increasing number of people are being exposed to this form of inactivity, and as a result, various interventions aimed at increasing physical activity during working hours are being developed. This study aims to investigate the differences in postural, muscular and physical activities resulting from two dynamic workstations, namely an elliptical trainer and a treadmill workstation, compared with a conventional sitting and standing workstation. Twelve participants completed five standardised office tasks in a laboratory setting at all workstations. No significant effect was found regarding changes in posture and the muscular activity was only significantly higher for the trapezius muscle (50th percentile: 8.1 %MVC) at the dynamic workstations. For the dynamic workstations, physical activity ranged from 4.0 to 14.9 × 10(-2) g, heart rate from 14.3 to 27.5 %HRR and energy expenditure from 1.8 to 3.1 METs. Practitioner Summary: Work-related physical inactivity is associated with health risk factors. In this study, physiological and postural effects of dynamic workstations were assessed in comparison to conventional workstations. No significant effects were found regarding changes in posture and muscular activity. Physical activity, heart rate and energy expenditure increased for the dynamic workstations.

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“…It is not possible to employ these procedures within the framework of production systems with real time capability. For this purpose, only physiological measurement techniques have been appropriate so far, such as electrocardiograms, electromyograms, or combined methods, such as the CUELA system (Ellegast et al 2009). The use of these measurement techniques allows data discrete in terms of time to be collected about the physiological strain situation of persons.…”

Section: Capabilities Of Existing Methods Of Workplace Design In Contmentioning

confidence: 99%

Adaptive Workplace Design Based on Biomechanical Stress Curves

Graichen

Stein

Deml

2014

Lecture Notes in Production Engineering

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The use of biomechanical models within the fields of workplace and working method design facilitates a detailed consideration of individual physiological capabilities and limitations. Based on motion capturing data of selected manual assembly tasks and the use of a biomechanical body model, body partoriented stress curves for the upper extremities have been derived. This functional description of physiological stress allows a body part-oriented evaluation of movements and handling positions in the right grasp area. Furthermore these relations have been transferred into body part, movement direction and handled weight dependent linear regression functions. Thereby working system could be enabled to perform physiological stress-oriented self-optimization processes. Applied to manual assembly tasks and in accordance with the individual skills of employees these functions could be the basis for a physiological stress-related adaptive assistant system. Automation engineering, hence, can provide employeespecific support, e.g., in the supply of components or advices for adaption of working method. Working systems thus are able to optimize and adapt themselves to the individual needs and abilities of the employees.

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Workload Assessment in Field Using the Ambulatory CUELA System

Cited by 35 publications

References 8 publications

Optimization of Inertial Sensor-Based Motion Capturing for Magnetically Distorted Field Applications

Optimization of Inertial Sensor-Based Motion Capturing for Magnetically Distorted Field Applications

Comparison of the postural and physiological effects of two dynamic workstations to conventional sitting and standing workstations

Adaptive Workplace Design Based on Biomechanical Stress Curves

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