Ergonomic evaluation of electric hedge trimmer using digital human modeling

Abstract

Maintenance of gardens in public and owned premises is becoming costlier. The traditional ways of garden trimming requiring manual labor are becoming obsolete and electric trimmers are extensively being used in maintenance of gardens. While carrying out trimming activity with electric hedge trimmer, operator undergoes various awkward posture(s) resulting into musculoskeletal disorders. The present study is undertaken to evaluate existing electric hedge trimmer workstation and suggest suitable modifications in order to reduce drudgery. The study uses anthropometric data from the literature for the user population for modeling of manikin. The concept of digital human manikin (DHM) is used for modeling and simulation purpose. Here DHM tools in CATIA software such as Rapid Upper Limb Assessment (RULA), carry analysis and biomechanics analysis are used for the analysis. Study presents ergonomic evaluation of farm worker(s) in Maharashtra state of India operating electric hedge trimmer. RULA score of 6-7 showed that existing electric hedge trimmer workstation is not safe for workers and must be changed soon or immediately. However, carry analysis depicted that existing weight of trimmer is acceptable. Biomechanics single action analysis showed considerable values of moments and forces coming on the various joints and body parts. The study suggested new improved workstation for the electric hedge trimming operation on the basis of the RULA and biomechanics analysis. The improved workstation not only reduced RULA score to acceptable limit but also significantly reduced values of moments and forces coming on the body of worker. Thus, the study explored the potential of DHM technique in the product design, especially in ergonomic design of new workstations or to improve existing workstations.