Automation of individual crop plant care in commercial vegetable crop fields has increased practical feasibility and improved efficiency and economic benefit if a systems approach is taken in the engineering design to mechanization that incorporates precision planting techniques.  In addition to the optimization in the biological productivity of crop plants when the spatial distribution of crop plants allows their uniform access to nutrients, water and light in an optimum utilization of field resources, the performance and efficiency benefits extend to the mechanization aspects of precision farming when a precise planting pattern can be implemented that facilitates automated plant localization as well as facilitating the interface of farming mechatronic systems with the crop plants and the surrounding soil.

 

This work describes the recent effort conducted at UC Davis to couple multi-row synchronized precision planting in a grid planting pattern with synchronized precision intra-row mechanical weed removal in a systems approach to automated weed control in vegetable crop production in California.  Selecting tomato as the target vegetable crop, a three-row synchronized intra-row weed control system was developed that utilized a co-robot design approach to automation of intra-row hoeing mechanism.  In this design, a co-robot actuator automatically positioned a pair of miniature hoes into the intra-row zone between crop plants.  Co-robot knife actuation was controlled using a priori knowledge of the crop planting pattern and real-time odometry data as the control input for knife positioning.  Low-frequency drift in the odometry control points relative to the actual plant locations was corrected occasionally as needed in real-time by a human supervisor monitoring system performance.

 

To facilitate the economic feasibility of a co-robot design approach to mechatronic weed control, the human resources need to be minimized while the robotic aspects need to be maximized.  This optimization was achieved by simultaneously developing a precision three-row synchronized transplanting system, where the three transplanting modules were mechanically synchronized to allow precise placement of the tomato seedlings in a three-row grid planting pattern.  Typically, transplanting modules used in vegetable crops in California act asynchronously, resulting in a random offset of the plant locations between rows in a plant care set.  This creates a chaotic management environment for the human supervisor monitoring co-robot weed control actuation decisions, forcing a decline in economic productivity either by increasing the human to robot resource ratio or by decreasing the travel speed of the vehicle.  In contrast, the systems approach utilizing a synchronous design for both planting and weed control actions demonstrated in this work, allows one human supervisor to monitor the actions of three co-robotic weed control modules, increasing the economic productivity.