How many bits of data are needed to understand lifting dynamics? (original) (raw)
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Biomechanical analysis of asymmetric and dynamic lifting task
2011
BIOMECHANICAL ANALYSIS OF ASYMMETRIC AND DYNAMIC LIFTING TASK by Xiaopeng Jiang Lifting tasks is one of the leading causes of occupational lower back disorders (LBD). Aimed at deriving internal forces of human musculoskeletal system during lifting, biomechanical models are utilized to address this problem. This thesis provides an indepth literature review of such modeling, and the results of experiments used to address LBD issues. An isometric pulling experiment was conducted to study the correlation between electromyography (EMG) and predicted muscle forces by AnyBody Modeling SystemTM with increasing hand loads. An infinite order polynomial (min/max) optimization criterion predicted percentage of maximum muscle forces, which achieved 98% correlation with normalized EMG. In a separate study, motion data during lifting of 13.6 kg (30 lb) weight at 0°, 30° and 60° asymmetry was collected by the OptiTrackTM sixcamera motion capture system to drive the AnyBodyTM model. Erector spinae w...
A user-friendly three-dimensional kinetic model for analyzing manual lifting tasks
International Journal of Industrial Ergonomics, 1999
Prevention of musculoskeletal disorders resulting from manual material handling tasks has been among the foremost concerns of industrial ergonomics researchers. Mital (1986, 1987) contributed significantly to the research in this area by developing a 3-D kinetic model for the analysis of manual lifting. Kromodihardjo and Mital's model (K-M model), and other kinetic models, rely on explicit kinematic information of the tasks being performed. Thus, time variations of displacements, velocities and accelerations (both linear and angular) for all body joints have to be known beforehand in order to perform an analysis. This, in turn, requires experiments to be conducted with individual subjects each time an analysis is needed. This is a tedious procedure and deters the generic use of such models. The present work was, therefore, initiated with the objective of encapsulating the K-M model into a form which could be readily used and applied to industrial situations. A comparison of the results obtained with the simplified model with results from K-M model shows an excellent match.
Biomechanical evaluation of lifting tasks: A microcomputer-based model
Computers & Industrial Engineering, 1988
Al~trlet--This paper discusses a static and dynamic biomechanical evaluation of sagittal lifting activities via a microcomputer model. The input to the developed model includes operator's anthropometric data, and sex. The model provides the reactive forces and torques at the various joints of the body expressed in both British and metric systems. Also, the model shows the calculated compressive force on the spine at the fifth lumbar/first sacral joint (L5/$1), and both kinematic and kinetic informatious are displayed. The model has a menu of five options: (1) to analyze stress imposed on the L5/$1 during a dynamic activity; (2) to determine maximum weight to be allowed during a dynamic motion; (3) to check stress on the spine (L5/$1) for specified static postures; (4) to determine maximum weight to be allowed for a static posture; or (5) to stimulate the lifting action and determine critical postures while performing lifting tasks based on static biochemical analysis.
IEEE Transactions on Rehabilitation Engineering, 1995
The combination of Workers' Compensation legal claims and the enactment of the Americans with Disabilities Act (1990) has created a need for more objective and realistic trunk muscle testing. The LIDOLift (Loredan, Inc.) is a computerized dynamometer which has the capabilities to test multijoint coordinated lifting tasks in isometric, isokinetic, and isoinertial modes of operation. The calibration of the electromechanical sensors produced R2 values greater than 0.999. In the validation of the isokinetic mode, the normalized rms error from the set velocity was less than 1% at higher set velocities, after the accelerative portion of the lit. In the technical validation of the isoinertial mode, the measured force was significantly different than the predicted force based on an isoinertial model. Consequently, the simulated mass was found to be larger than the intended mass. However, the relative difference decreased as the intended mass increased. Next, an experimental protocol was utilized to determine the validity of the isoinertial mode in the work and joint spaces. A sagittal planar dynamic biomechanical model was used to provide the basis of comparison between lifts performed with the LIDOLift and with free weights. Analyses of covariance showed statistical differences for most work and joint space variables. However, the relative difference between the two for some variables may be functionally negligible. Important guidelines for clinical protocols using the isokinetic and isoinertial modes of this simulator are delineated. Areas of technological improvement have been identified to close the gap between the simulated isoinertial condition and the free weight lifting task.
IEEE Transactions on Rehabilitation Engineering, 1995
The combination of Workers' Compensation legal claims and the enactment of the Americans with Disabilities Act (1990) has created a need for more objective and realistic trunk muscle testing. The LIDOLift (Loredan, Inc.) is a computerized dynamometer which has the capabilities to test multijoint coordinated lifting tasks in isometric, isokinetic, and isoinertial modes of operation. The calibration of the electromechanical sensors produced R2 values greater than 0.999. In the validation of the isokinetic mode, the normalized rms error from the set velocity was less than 1% at higher set velocities, after the accelerative portion of the lit. In the technical validation of the isoinertial mode, the measured force was significantly different than the predicted force based on an isoinertial model. Consequently, the simulated mass was found to be larger than the intended mass. However, the relative difference decreased as the intended mass increased. Next, an experimental protocol was utilized to determine the validity of the isoinertial mode in the work and joint spaces. A sagittal planar dynamic biomechanical model was used to provide the basis of comparison between lifts performed with the LIDOLift and with free weights. Analyses of covariance showed statistical differences for most work and joint space variables. However, the relative difference between the two for some variables may be functionally negligible. Important guidelines for clinical protocols using the isokinetic and isoinertial modes of this simulator are delineated. Areas of technological improvement have been identified to close the gap between the simulated isoinertial condition and the free weight lifting task.
Individual trunk muscle and ligament forces during dynamic lifting
Journal of Biomechanics, 1992
The purpose of this project is to develop methods and procedures for graphic simulation and ergonomic evaluation of work as a tool for engineers. A system is built up consisting of a modeller, a multi body systems analysis module, a data base for object storage, and an anthrop+ metric human body model. Product models to be assembled are obtained from the CAD-system in which they are designed. The ergonomic evaluation includes analysis of space requirements, reach distances, visual obstacles or constraints and comfort angles of joints. Biomechanical calculations are also made resulting in data which describe the instantaneous torque and resultant force on joints and body segments as functions of time. These values can be compared with tissue strength data and maximal capacities for force exertion. The lower the values the better, but the time course must also be considered and an integrated value representing the dose of load on each joint calculated. When the loading on one joint must be traded against another, an optimization procedure could be used to reach a favourable loading situation provided that a suitable criterion can be formulated. At present no such criteria have been tested, however. The control of the animation presents particular requirements depending on the number of degrees of freedom of the body model. When the number is low, key frame animation can be used. When it gets higher it becomes very tedious to control each degree of freedom separately, then, for example, gesture control or algorithmic animation must be used.
Effects of kinematics constraints on hand trajectory during whole-body lifting tasks
Neuroscience Letters, 1999
Trajectories of the hands and whole-body center of mass were studied during whole-body lifting tasks. The movements of different parts of the body were monitored with the ELITE system. Subjects were instructed to lift to shoulder height an object placed at one of two distances (5±45 cm) before them on the¯oor. The lifts were performed both with and without kinematics constraints (i.e. to produce a straight hand trajectory while lifting, and to lift without any instructions, respectively). Hand trajectories were roughly straight when performed under the constrained condition, but curved when performed without instruction. Hand velocity curves showed bell-shaped pro®les. In both groups, body centers of mass (whole-body, upper and lower part) were calculated and their trajectories showed invariant sagittal displacements. These results support the idea that movement contributes to postural control and, reciprocally, that whole-body center of mass is a robust and controlled variable which plays an important role in hand trajectory formation. q
Journal of Biomechanics, 2010
a b s t r a c t L5/S1, hip and knee moments during manual lifting tasks are, in a laboratory environment, frequently established by bottom-up inverse dynamics, using force plates to measure ground reaction forces (GRFs) and an optoelectronic system to measure segment positions and orientations. For field measurements, alternative measurement systems are being developed. One alternative is the use of small body-mounted inertial/magnetic sensors (IMSs) and instrumented force shoes to measure segment orientation and GRFs, respectively. However, because IMSs measure segment orientations only, the positions of segments relative to each other and relative to the GRFs have to be determined by linking them, assuming fixed segment lengths and zero joint translation. This will affect the estimated joint positions and joint moments. This study investigated the effect of using segment orientations only (orientation-based method) instead of using orientations and positions (reference method) on threedimensional joint moments. To compare analysis methods (and not measurement methods), GRFs were measured with a force plate and segment positions and/or orientations were measured using optoelectronic marker clusters for both analysis methods. Eleven male subjects lifted a box from floor level using three lifting techniques: a stoop, a semi-squat and a squat technique. The difference between the two analysis methods remained small for the knee moments: o 4%. For the hip and L5/S1 moments, the differences were more substantial: up to 8% for the stoop and semi-squat techniques and up to 14% for the squat technique. In conclusion, joint moments during lifting can be estimated with good accuracy at the knee joint and with reasonable accuracy at the hip and L5/S1 joints using segment orientation and GRF data only.