Michael Nørremark

Hortibot: Feasibility study of a plant nursing robot performing weeding operations - part IV

Based on the development of a robotic tool carrier (Hortibot) equipped with weeding tools, a feasibility study was carried out to evaluate the viability of this innovative technology. The feasibility was demonstrated through a targeted evaluation adapted to the obtainable knowledge on the system performance in horticulture. A usage scenario was designed to set the implementation of the robotic system in a row crop of seeded bulb onions considering operational and functional constraints in organic crop, production. This usage scenario together with the technical specifications of the implemented system provided the basis for the feasibility analysis, including a comparison with a conventional weeding system. Preliminary results show that the automation of the weeding tasks within a row crop has the potential of significantly reducing the costs and still fulfill the operational requirements set forth. The potential benefits in terms of operational capabilities and economic viability have been quantified. Profitability gains ranging from 20 to 50% are achievable through targeted applications. In general, the analyses demonstrate the operational and economic feasibility of using small automated vehicles and targeted tools in specialized production settings.

Robotic weed monitoring

Abstract In this paper, an integrated management system for the planning and activation of a field monitoring task is presented. The architecture of the system is built around a mobile robotic unit. The internet-based architecture of the system includes a station unit that works as a mobile on-farm operating console, the mobile robotic unit and a field server for generating and storing maps. The hypothesis is that it is possible to automate the planning and execution of the operation of monitoring the in-field weed density and species distribution. The developed planning system includes the automatic field geometrical representation and the route planning for the mobile unit. For the field representation two algorithmic approaches for automated track generation were used. For the route planning, a graph-based field coverage algorithm and a discrete grid-based path planning method were used. The low computational requirements of the implemented algorithms make it feasible to adopt a real-time re-planning strategy in which a set of new planning problems are solved based on the latest information. The central part of such a planning, concerns the dynamic re-evaluation of the initial plan for sampling and routing based on the on-line analysis of the samples. This provides the basis for a fully sequential adaptive adjustment of the sampling procedure after each individual sampling. It is expected that such a dynamic targeted sampling and routing system will reduce the overall cost and time consumption of the weed monitoring operation.

Sensor and control for consistent seed drill coulter depth

The novel position system detected the high-frequency drill coulter depth vibrations.By coulter down pressure control, the low-frequency depth variations were minimised.The system provided a mean depth deviation from the desired coulter depth of ź1.2mm.A three-position control system was found to be the best, cost-efficient solution. The consistent depth positioning of seeds is vital for achieving the optimum yield of agricultural crops. In state-of-the-art seeding machines, the depth of drill coulters will vary with changes in soil resistance. This paper presents the retrofitting of an angle sensor to the pivoting point of a drill coulter, providing sensor feedback to a control system that via an electro-hydraulic actuator delivers a constant coulter depth. The results showed a strong correlation between the angle of the coulter and the coulter depth under static (R2=1.00) and dynamic (R2=0.99) operations, verified by a sub-millimetre accurate positioning system (iGPS, Nikon Metrology NV, Belgium) mounted on the drill coulter. At a drill coulter depth of 55mm and controlled by an ordinary fixed spring loaded down force, the change in soil resistance reduced the mean depth by 23mm. By dynamically controlling the spring loaded down force based on the angle sensor, the mean depth was independent of the seedbed resistance change as shown from tests in soils ranging from sand to gravel. The PID controller was most effective because it providing a mean depth deviation from the target depth of -0.17mm and +0.08mm for sand and gravel, respectively. The most cost efficient control function was found to be the three-position control system, resulting in a mean depth deviation from the target depth of -0.89mm and -1.18mm for sand and gravel, respectively. A Fast Fourier Transform (FFT) analysis of the coulter depth measurements showed that the control system also provided a damping effect on the coulter depth variations. The research showed that it is possible to minimise the low-frequency drill coulter depth variations and provide a consistent coulter depth independent of soil conditions by using the developed sensor system and control system.

User-centered and conceptual technical guidelines of a plant nursing robot

Current service robots, e.g. lawn movers and vacuum cleaners, have rather crude behaviors and limited sensing with the environment. Technological foresights indicate that the next generation of service robots should demonstrate a high degree of autonomy, reliability, minimum environmental impact, and interact in a sensible way with the user. There is a need to determine the functional requirements for the energy effective robot system of tomorrow used in bioproduction from the perspective of various stakeholders together with the development of a high-level framework for designing/prototyping, focusing on the common functionalities among mobile robots.

Seed drill depth control system for precision seeding

Abstract An adequate and uniform seeding depth is crucial for the homogeneous development of a crop, as it affects time of emergence and germination rate. The considerable depth variations observed during seeding operations - even for modern seed drills - are mainly caused by variability in soil resistance acting on the drill coulters, which generates unwanted vibrations and, consequently, a non-uniform seed placement. Therefore, a proof-of-concept dynamic coulter depth control system for a low-cost seed drill was developed and studied in a field experiment. The performance of the active control system was evaluated for the working speeds of 4, 8 and 12 km h−1, by testing uniformity and accuracy of the coulter depth in relation to the target depth of −30 mm. The evaluation was based on coulter depth measurements, obtained by coulter position sensors combined with ultrasonic soil surface sensors. Mean coulter depth offsets of 3.5, 5.3 and 6.3 mm to the target were registered for the depth control system, compared to 8.0, 9.1 and 11.0 mm without the control system for 4, 8 and 12 km h−1, respectively. However, speed did not affect the coulter depth significantly. The control system optimised coulter depth accuracy by 15.2% and at 95% confidence interval it corresponded to an absolute reduction in the coulter depth confidence span of 10.4 mm. The spatial variability, due to variation in soil mechanical properties was found to be ±8 mm, across the blocks for the standard drill and when activating the coulter depth control system this variability was reduced to ±2 mm. The system with the active control system operated more accurately at an operational speed of 12 km h−1 than at 4 km h−1 without the activated control system.