Subjective versus objective ergonomic analysis methods

August 4, 2021

Ergonomic assessments block into three categories: observational methods, video-based analyses, and motion measurement methods. Observational methods are frequently adduced as paper-pencil methods since these work with an ergonomics expert on the field observing work while filling in the paper forms helping to define risk. Results are based on the skills and previous practice of the expert.

Video-based methods work from the two-dimensional recording of the processes using learning algorithms that recognize postures on the frames. Earlier, these methods mainly worked by processing videos on the computer, but now a smartphone can provide such results with a suitable app.

Motion measurement methods record sensor positions in the three-dimensional space. With that data and the kinematic chain of the human mannequin, motions reappear in the model space for analyses and redesign of motion sequence, environment, and testing improvements.

Observational and video-based methods are subjective since the angle of recording, the postures perceived to depend on the assessors' view. Observation can take a long time and provides results later when all the data is gathered. It concentrates on the worst positions occurring during the process, not considering all postures of the workers. When the basis is a video, data is gathered from a two-dimensional recording. Depending on the position of the person recording, it can show alternate views. Also, it can be used only if one person is present in the film. Because of the numerous options, learning algorithms usually need human help and supervision in the assessment. Therefore both methods above ask for an ergonomics expert to be present. However, even with that, they cannot provide the punctuality promised by the motion measurement methods.

Motion measurement uses sensors to define exact positions in the three-dimensional space. They consume only the time of dressing up and down, and the amount of the recorded motion. The recording doesn't depend on the people in the surroundings, and a technician can proceed. Analyses give the same result for a given recording in any case since the rater and the operator don't affect the recorded data.

While subjective methods are capable of screening the work processes, assessing risks roughly and ready, motion measurement methods provide punctual results, detailed analyses of work processes for intricate opinions, and suggestions for improvement. Necessarily for suggestions and improvements, an ergonomist can give a hand!


ViveLab Ergo is a cloud-based ergonomic lab for modeling objects, machines and human beings moving together in a virtual 3D space. Thanks to its massive anthropometric database and 7 built-in ergonomic analyses it precisely simulates, analyzes and validates human interactions with industrial and other environments. With the help of the ViveLab Ergo the ergonomic analysis of constructions is possible in the planning phase without prototype production by simulation in the virtual space.

Our mission is to provide fast and accurate three-dimensional virtual ergonomic tests, analysis and planning for wide range of companies to create optimal working environments and workflows for health, efficiency and competitiveness.

Related Posts