Abstract: To explore the physiological information of lumbar muscle changes of combine harvester drivers during the driving process, the evolution process of lumbar muscle fatigue of combine harvester drivers was studied by contrast. The surface electromyographic signals of the left and right erector spinae muscle of 10 combine harvester drivers were collected respectively in the process of 120 min harvest driving and 120 min sitting. The change rule of iEMG, RMS, MPF, MF and sample entropy of the surface electromyographic signals with driving time was analyzed in different groups. The validity representing lumbar fatigue of characteristic parameters was investigated. The results demonstrate that the left and right erector spinae muscles are submitted to fatigue after 120min harvest driving operation. In the control group, there were no significant differences in time domain, frequency domain and non-linear indexes of the surface electromyography signals of the left and right erector spinal muscles before and after the task (P > 0.05). In the experimental group, the iEMG and RMS of the surface electromyography of lumbar erector spine muscle increased significantly with the driving time (P < 0.05), while the MPF, MF and sample entropy decreased significantly (P < 0.05). Compared with linear index, the variation coefficient of sample entropy is the smallest, which can better represent the physiological information of lumbar fatigue and has good stability.

Key words: combine harvester, lumbar fatigue, surface electromyography, time domain analysis, frequency domain analysis, SampEn