Ergonomic Workplace Design Analysis: Development of a practitioner's tool for enhanced productivity

Doctoral thesis, 2004

There is a lack of pragmatic methods to assess musculoskeletal load risks when planning for production when there is no human operator to observe that performs the tasks. Existing methods are generally either expensive computer manikin software that is complicated to learn and use, simple digital human models for static and episodic analysis best used by trained ergonomists or methods in need of full-scale prototypes for observation. The suggested method in this report is intended to be used by production engineers who are interested in ergonomics and involved in pre-production planning. The ideal situation is when there is room for changes in both product and workplace design, the ambition exists to achieve high productivity and the insight exists that this is best accomplished when the designs are optimized over both production time and operator load. A concept of a complete tool is sketched, incorporating a simple CAD tool for workplace design, a language to describe the intended tasks to be carried out and a knowledge based system for prompting the operator for needed input data and for analysis of the expected musculoskeletal load. To test the validity of the method a prototype program was developed that incorporates part of the sketched tool. The analysis is based on a “Cube model” consisting of the integrated evaluation of the three factors of work posture, force and/or weight, and repetition. The prototype tool was built using an MTM method called SAM as a method for task description and was named ErgoSAM. ErgoSAM was evaluated in three studies at several final assembly stations of ITT Flygt and the Volvo Car Corporation and was found to be able to detect and evaluate musculoskeletal load with a high degree of correlation to alternative observation methods.