MODELLING AND SIMULATION OF FARM WORKFLOW USING TIMED COLOURED PETRI NETS

ABSTRACT Agriculture being one of the most important bedrock of the society contributes to the societal development and growth. Most existing works modelled the sequential flow of agricultural process, which does not implement how agricultural machineries and equipment can be shared between farmers to further increase production rate. Hence, this research developed a model of farm workflow with inclusion of machinery and equipment sharing policy. Four different farmlands from National Centre for Agricultural Mechanization (NCAM) Idofian, Kwara State each of the size of 1 hectare were used as a case study for this research work. The data collected for the for farmlands showed the operating time for each farming operations and the waiting time after it. For the first farmland clearing operation spanned for a period of 1.03hrs and waiting time of 10.00hrs, 1.12hrs and 10.00hrs for land 2, 1.20hrs and 10.00hrs for land 3 and 1.30hrs and 10.00hrs for the fourth land. This also goes for other farming operations till the last one which is planting. The model abstracted the workflow of the various agricultural processes required for maize plantation starting from clearing till planting with their annotated processing time and idle intervals. A second scenario was abstracted improving on the real system using HTCPN, which allows for the release and sharing of the farm machinery to another farmland when the previous farmland goes idle. This depicts the tractor sharing policy. These two scenarios were simulated, the first scenario simulates a particular farmland following the ideal farm work flow with both the operating time and waiting time. The transition ‘start clearing’ is first enabled and fired which started the farming operation clearing for a period of 1.03hrs until the end of the clearing operation when the tractor and the land goes idle for a period of 10.00hrs, then the operations after this follow the same sequence and the flowtime for the first farmland is collected. This process is then repeated for the other farmlands. The second scenario is done by modelling two farmlands together whereby when farmland 1 finishes its clearing operation after 1.03hrs it releases its tractor to farmland 2 to perform its own clearing operation for a period of 1.20hrs instead of going idle, this is repeated for the remainder of the operations and the flowtime is collected. The developed HTCPN model was validated by carrying out a statistical analysis (T-Test) between the simulated and the real time for the workflow order of 5% level. The simulated results of the developed HTCPN model revealed that the total operation time of both farmlands in the first scenario is 14.97hrs and together with the waiting time it makes 69.97hrs and using the second scenario the total operation time for both the farmland is 13.58hrs which is a drastic reduction in time. The validation of the developed HTCPN model showed there is no significant differences between the simulated and real time for workflow using the sharing policy. This research developed a model of farm workflow using tractor sharing policy as a basis. It could serve as a reference model for studying the workflow using numerous farm machineries.