Skills development of mechanised softwood sawtimber cut-to-length harvester operators

Wenhold, Roland Marius (2018-03)

Thesis (MScFor)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT: In this study, a South African pine sawtimber mechanised cut-to-length harvesting operation – comprising felling, debarking, debranching and cross cutting of log assortments – was analysed using .stm-files from StanForD software. The objective of the analysis was to describe and model productivity development learning curves of beginner harvester operators in both clear-felling and thinning operations. A cohort of trainee operators were selected based on the results of a comprehensive battery of psychometric tests that assessed their aptitude for the complex array of decision-making required of harvester operators. These trainees subsequently completed several sequential tests on a harvester simulator. Following the simulator training, operators commenced with work on machines (harvesters) themselves until they were considered capable of working unsupervised. Within the framework of this progression of operator selection, simulator training and in-field operations, it was possible to model a potential learning curve of a typical beginner harvester operator in softwood sawtimber in both clear-felling and thinning operations. With regards to simulator training, the results of this study show that, on average, a trainee operator will start at a performance level (PL) of 60% lower than the population’s performance level (PPL) and end with a PL of 24% higher than the PPL. Furthermore, when the PL of an average simulator trainee was measured over a period of 9.2 days or 27 tests (three tests per day), it was evident that his PL improved with 269% following the efficient simulator training. Once in-field, thinning operators worked with an average tree size of 0.18m3 where they started at a productivity of 13.71 m3 ·PMH-1 (cubic meter per productive machine hour) at month one and managed to increase their productivity to 38.96 m3 ·PMH-1 (overall average = 28.8 m3 ·PMH-1 ) at the end of month 12. Clear-felling operators’ felling productivity level on an average tree volume of 0.54m3 started at 27.5 m3 ·PMH-1 in month one and increased to 43.75 m3 ·PMH-1 (overall average = 41.9 m3 ·PMH-1 ) at the end of month 12. Finally, on average, a thinning operator can reach the end of the learning phase after nine months. The two clear-fell operators reached the end of their learning curve after five and eight months respectively. On average, thinning operators increased their performances by 218%, while clear-fell operators increased theirs by 104%. These findings suggest acceptable learning periods and performance increases for beginner harvester operators.

AFRIKAANSE OPSOMMING: In hierdie studie is 'n Suid-Afrikaanse gemeganiseerde sny-na-lengte oesoperasie van denneboom saaghout wat uit sloping, ontbasting en dwarssnitte van verkeie produkte bestaan, ontleed. Die ontleding is gedoen met die doel om produktiwiteitsontwikkeling leerkurwes van beginner-oesoperateurs in beide kaalkap- en verdunningsoperasies te ontwikkel en verduidelik met behulp van .stm-lêers van die sogenoemde StanForDsagteware. 'n Groep leerder-operateurs is op grond van ʼn omvattende reeks psigometriese toetse gekies om hulle bekwaamheid te evalueer ten opsigte van ‘n komplekse verskeidenheid besluite wat vereis word van die oesoperateurs. Hierdie leerlinge het gevolglik verskeie sekwensiële toetse op die simulator voltooi. Na afloop van die simulatoropleiding het die operateurs met die fisiese masjiene begin werk totdat hulle bevoeg beskou is om onbegeleid te werk. Binne die raamwerk van hierdie vordering van operateur-seleksie, simulatoropleiding en in-veld-produksie-ontwikkeling, is dit moontlik om 'n potensiële leerkurwe van 'n tipiese beginner-oesoperateur in beide kaalkap- en verdunnings van saaghout operasies te modelleer. Wat simulatoropleiding aanbetref het die resultate van hierdie studie gewys dat simulatorleerder-operateurs se prestasievlak (PV) van 60% laer as dié van die populasie se gemiddelde prestasievlak (PPV) sal wees en dat hy met 'n PV van 24% hoër as die PPV sal eindig. Verder sal 'n gemiddelde simulator-leerder oor 'n tydperk van 9,2 dae of 27 toetse (drie toetse per dag) van doeltreffende simulatoropleiding sy prestasie met 269% verhoog met betrekking tot sy aanvanklike PV. Tydens werk in die veld het verdunningsoperateurs gedurende die 12 maande-studietydperk met 'n gemiddelde boomgrootte van 0.18 m3 gewerk, waar hulle met 'n produktiwiteit van 13.71 m3 ·PMU-1 (kubiekemeter per produktiewe masjien uur) (maand 1) begin het en verder daarin geslaag het om hul produktiwiteit na 38,96 m3 ·PMU-1 (algehele gemiddelde = 28.8 m3 ·PMU-1 ) aan die einde van maand 12 te verhoog. Die kaalkap-operateurs se produktiwiteitsvlak gedurende die 12 maande studietydperk op 'n gemiddelde boomgrootte van 0.54 m3 het by 27.5 m3 ·PMU-1 (maand 1) begin en het aan die einde van maand 12 tot 43.75 m3 ·PMU-1 (gemiddelde van 41.9 m3 ·PMU-1 algeheel) verhoog. Op die ou-end kan 'n gemiddelde verdunningsoperateur die einde van sy leerkurwe na nege maande bereik. Die twee kaalkap-operateurs het onderskeidelik na vyf en agt maande die einde van hul leerkurwes bereik. Oor die algemeen het die verdunning- en kaalkap-operateur hulle prestasies onderskeidelik met 218% en 104% verhoog. Hierdie bevindings suggereer aanvaarbare leertydperke en prestasieverhogings vir beginner-oesoperateurs.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/103831
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