Ergoniza Intelligent technical foundations
This manual describes the conceptual, methodological, and operational foundations of Ergoniza Intelligent. It explains how the system represents human physical activity, how it calculates biomechanical and ergonomic indicators, and how the resulting assessments should be interpreted.
Table of contents
- 1 INTRODUCTION
- 1.1 What is Ergoniza Intelligent?
- 1.1.1 What Ergoniza Intelligent is not
- 1.2 What hardware do I need to use Ergoniza Intelligent?
- 1.3 What types of analysis can I perform with Ergoniza Intelligent?
- 1.4 What data are required to perform an analysis with Ergoniza Intelligent?
- 1.5 Responsibility for use
- 2 ERGONIZA INTELLIGENT OPERATING MODES
- 3 UNITS, SYSTEMS, AND REFERENCE PLANES
- 3.1 Global reference system
- 3.2 Model reference system
- 3.3 Principal reference planes and anthropometric planes
- 4 ANGLES BETWEEN BODY SEGMENTS
- 5 THE ERGONIZA INTELLIGENT BIOMECHANICAL MODEL
- 5.1 Segments and joints
- 5.1.1 The head-neck segment
- 5.1.2 The torso and pelvis segments
- 5.1.3 The upper arm and thigh segments
- 5.1.4 The forearm and lower leg segments
- 5.1.5 The hand segment
- 5.1.6 The foot segment
- 5.2 Range-of-motion limits
- 5.3 Inertial parameters
- 5.3.1 Centers of gravity
- 6 BASE OF SUPPORT, CENTER OF PRESSURE, AND STABILITY
- 6.1 Global slipping
- 7 SUPPORT MODELING
- 7.1 Ground reaction forces at the feet during bipedal stance
- 7.1.1 Calculating the vertical components of ground reaction forces at the feet
- 7.1.2 Calculating the horizontal components of ground reaction forces at the feet during bipedal stance
- 7.2 Ground reaction forces at the feet during single-leg stance
- 7.3 Partial slipping
- 7.4 Reaction moments at the foot supports
- 7.5 Knee supports
- 7.6 Hip supports
- 7.7 Modeling seated posture in a chair
- 7.7.1 Detecting seated posture in a chair
- 7.7.2 Contacts considered when seated in a chair
- 7.7.3 Distribution of support reactions when seated in a chair
- 7.7.4 Simplifications assumed when modeling seated posture
- 7.7.5 Lower-limb joint loads when seated in a chair
- 7.7.6 Consideration of the chair backrest
- 7.7.7 Scope and limitations of the seated-posture model
- 7.8 Stabilogram and distribution of support reactions
- 8 JOINT LOAD CALCULATION
- 8.1 Upper-limb joint loads
- 8.2 Lower-limb joint loads
- 8.2.1 Lower-limb joint loads in an unsupported model
- 8.2.2 Lower-limb joint loads in a supported model
- 8.3 Residual moments
- 8.4 Joint loads
- 8.5 Limitations in calculating moments and biomechanical exertions
- 9 ASSESSMENT OF ERGONOMIC RISK FACTORS
- 10 OVEREXERTION RISK ANALYSIS
- 10.1 Maximum joint capacities
- 10.1.1 Exertion assessment
- 10.2 Recommended percentage of Maximum Voluntary Contraction (%MVC) in single-posture analysis
- 10.2.1 Recommended %MVC for momentary exertions
- 10.2.2 Recommended %MVC for static exertions
- 10.2.3 Recommended %MVC for repetitive tasks
- 10.3 Cumulative exertion load in multiple-posture analysis
- 10.3.1 Concept of cumulative exertion load
- 10.3.2 Instantaneous relative exertion
- 10.3.3 Determining the exposure time limit using MET curves
- 10.3.4 Calculating the temporal exertion dose
- 10.3.5 Separation by joint, biomechanical channel, and functional muscle group
- 10.3.6 Temporal integration of the dose and cumulative-load update
- 10.3.7 Partial recovery between exertions
- 10.3.8 Consideration of repetitive tasks and rest between repetitions
- 10.3.9 Final result and ergonomic interpretation
- 10.4 The 3CC-r model and Recommended Moment in multiple-posture analysis
- 10.5 Conceptual differences between single- and multiple-posture analysis
- 10.6 Displaying exertions on the model
- 10.6.1 Display in single-posture analysis
- 10.6.2 Display in multiple-posture analysis
- 10.7 Limitations of joint exertion as a sole risk indicator
- 10.7.1 Limitations in single-posture analysis
- 10.7.2 Limitations in multiple-posture analysis, the 3CC-r model, and cumulative exertion load
- 11 POSTURAL RISK ANALYSIS
- 11.1 Joint ranges of motion
- 11.2 Postural discomfort
- 11.2.1 Measuring postural discomfort: psychophysical basis
- 11.2.2 Absolute discomfort assessment
- 11.2.3 Time-relative postural discomfort in single-posture analysis
- 11.2.4 Time-relative postural discomfort in multiple-posture analysis
- 11.2.5 Limitations and precautions in use and interpretation
- 11.2.6 Displaying discomfort on the model
- 11.3 Measuring risk from adopted postures using the REBA and LUBA methods
- 11.3.1 Measuring postural risk using the REBA method
- 11.3.2 Measuring risk from awkward postures using the LUBA method
- 12 LUMBAR SPINE COMPRESSION AND SHEAR RISK ANALYSIS
- 12.1 Calculating compression and shear at the L4/L5 intervertebral disc
- 12.1.1 Force associated with intra-abdominal pressure
- 12.1.2 Iterative model for calculating trunk muscle forces
- 13 LIFTING-TASK ANALYSIS
- 13.1 Objective, scope, and basis of the analysis
- 13.2 Defining lifting tasks, general parameters, and anthropometric adjustment
- 13.3 Origin and destination positions
- 13.4 Load weight, frequency, and coupling
- 13.5 Analysis results: Recommended Weight Limit, Lifting Index, and Composite Lifting Index
- 14 POSTURE-SEQUENCE ANALYSIS
- 14.1 Creating a posture sequence manually
- 14.2 Timeline, interpolation, and animation editing
- 14.3 Artificial intelligence for posture detection
- 14.3.1 Two artificial-intelligence modes in Ergoniza Intelligent
- 14.3.2 AI versus MoCap: scope, limitations, and user validation
- 14.4 Importing data from Xsens
- 14.4.1 Adapting MVNX data to the Ergoniza Intelligent model
- 14.5 Loads and conditions that vary throughout the posture sequence
- 15 APPENDICES
- 15.1 APPENDIX 1: CALCULATING UPPER-ARM AND THIGH ROTATIONS
- 15.1.1 How Ergoniza Intelligent calculates humeral and femoral rotation
- 15.1.2 How singularities are resolved
- 15.2 APPENDIX 2: Details of postural-discomfort calculation for momentary or unsustained postures
- 15.2.1 Transition function for momentary discomfort
- 15.2.2 Determining r0 for the upper limbs, neck, and trunk
- 15.2.3 Determining r0 for the lower limbs using isocomfort equations
- 15.2.4 Operational age adjustment of effective ROM
- 16 REFERENCES