Design, development and ergonomic evaluation of a manual cutter for mat-type paddy nursery based on a human-centered approach

BackgroundThe cutting operation of the mat-type paddy nursery for mechanical transplanting poses significant human postural challenges, leading to potential health risks for farmers.ObjectiveA nursery cutter was designed, developed and evaluated considering the ergonomic guidelines for the human farm workers.MethodsAnthropometric dimensions of 5^th and 95^th percentile of the Indian Agricultural workers was considered for the design of nursery cutter. The total length of cutter 1205 mm aligns with 80% of the 95^th percentile male acromial height ensuring operator comfort. Additionally, a 413 mm handle crossbar length (95^th percentile female elbow-elbow breadth) and a 280 mm width (5th percentile for both genders) were selected for ergonomic compatibility and ease of operation. Computer-aided design with human manikin was simulated for the postural evaluation.ResultsThe developed equipment could achieve a cutting capacity of 325-425 mats/ h with uniform cutting. The cost comparison analysis revealed that cutting mats for one hectare with the manual nursery cutter was significantly lesser (INR 71.00-89.00) than using a sickle/knife (INR 162.00-202.00) or an indigenous cutter (INR 146.00-172.00). Physiological results of workers showed that heart rates, oxygen consumption rate and energy expenditure rate ranged from 104-120 bpm, 0.66-0.88 l/min, and 13.7-18.37 kJ/min, respectively, indicating that the physical demands on workers were within moderate limits rather than heavy workload as in case of other conventional methods.ConclusionsAdopting ergonomic design equipment, the PAU manual nursery cutter can potentially enhance productivity, timeliness in operation, reduce operator fatigue, and mitigate health risks associated with nursery cutting operations.