BoniRob field robot measures maize plants

Remote travelling in the field – the independent BoniRob field robot has already been admired at AGRITECHNICA 2009 and the DLG field days in 2010. Here, it was impressively demonstrated as to just how good the navigational system functions – first on the basis of artificial plants and later outdoors in a field of maize. At the DLG 2010 field days, BoniRob did its rounds in the test field without human assistance. It did this with the utmost reliability and without damaging any plants.

The aim of the development project promoted by BMELV and BLE is, of course, not only the navigation. The navigation developed by the Robert Bosch GmbH is necessary to let the robot built by AMAZONE travel on its own across the field and to suitably place the exchangeable modules within the robot above the plants. For this, Osnabrück University has developed a sensor module which enables automatic individual plant marking.

For the marking procedure light matrixes, laser distance sensors, 3D cameras and a spectral imaging system are used. The latter can store data similar to the nitrogen sensors already used in agriculture, however, this is done at a high spatial resolution of a few millimetres. In addition, the sensor does not measure a quotient from specific wavelengths but determines, for every measurement point, the whole infrared spectrum. The resulting data rate of 70 MB per metre travelled distance is stored via an industrial PC.

Via a RTK-GPS system, all the data from the sensors is stored linked to locality and time. In this way data can be assigned to the individual plants at different times.

Information regarding shape and size of the plants can be achieved with a light matrix. It is an array formed of light matrixes in which the plants sit between the sender and receiver units. The sensor creates a silhouette of the plants. From this data, the position of the plant, the plant height and the plant width can be determined. By assigning the data to the individual plants, growth can be monitored via several test-runs.

BoniRob is equipped with a complex chassis. The track width and the height of the robot can be adjusted enabling it to adapt to different situations in the field, such as row spacing or plant height. Track widths of 0.75 m to 2 m and a ground clearance of 0.4 m to 0.8 m are adjustable. Every wheel can be steered individually. This makes the robot very manoeuvrable and ensures its optimum following of the row.

The robot is designed in modules. So the sensors from the University can be easily removed. The free space then can be used for other modules. Here modules, such as for example, for selective weed control, for harvesting vegetables or for other sensor tasks can be used.

For future testing of the system, test-runs with plant breeders are planned for 2012. In this way the efficiency of the system and the significance of the data can be appraised. In parallel, the realisation of BoniRob as a robot platform is being worked on and so, with the aid of exchangeable modules, applications can be developed, which will include some that so far no one has yet thought of. In this way, the robot could be used similar to a tractor and fulfil different tasks.

Category	Specification
Basic data	Vehicle dimension (L x W x H):	200 cm x 120 cm x 100 cm
	Track width:	75 – 200 cm (variable)
	Ground clearance:	40 – 80 cm (variable)
	Total weight:	approx. 600 kg
	Max. speed:	approx. 5 km/h
	Capacity:	approx. 2 kW
System technology	PC/Microcontroller/Embedded Systems; Ethernet/CAN, Wireless LAN, Middleware-based communication structure, database
Navigation	2D Laser scanner, 3D Laser scanner, Acceleration sensors, Gyroscope, encoder, RTK-DGPS; SLAM (simultaneous localisation and mapping)
Phenotypisation maize	Light curtain, colour camera, spectral imaging, 3D ‘Time-of-Flight’ camera, opto-electrical distance sensors
Safety technology	Emergency off-switch, isolation monitoring, ultrasonic sensors, Software monitors (roboterintern, WLAN)
Simulation technology	3D dynamic simulation (Gazebo, Microsoft Robotics Studio)