Selective asparagus harvesting with autonomous robot
19/04/2024 Turck Banner Ltd
AvL Motion is breaking new ground – with a machine for the selective harvesting of white asparagus, 'garnished' with high precision sensors as well as RFID and fieldbus technology from Turck
The Dutch startup company AvL Motion put on the market a machine for the fully autonomous selective harvesting of white asparagus. In its search for an ultrasonic sensor for height control, the company came across the IO-Link compatible RU40U from Turck. Through the subsequent collaboration more sensor technology was integrated in the vehicle, including miniature inductive proximity switches, precise encoders as well as LE550 laser sensors from Banner Engineering and the robust Li500-Q25 linear position sensor. AvL also uses the TN-Q14 RFID read/write head for the identification of harvesting modules, while the TBEN-S2-4IOL compact I/O module transfers IO-Link signals to the PLC.
AvL Motion uses two of the ultrasonic sensors RU40U with IO-Link to measure the distance between the asparagus bed and the pneumatically controlled internal frame of the machine. In spite of the partly dusty or rain-slicked subsoil, the sensors enable a stable measurement of the height, which users can set on an HMI. “Turck impressed us with the outstanding quality and fast delivery of their product. We therefore stayed with the manufacturer for other components,” says AvL CEO Arno van Lankveld.
Optical process replaces trained eye
The harvesting process of the AvL Compact S1560 is very dynamic. Once the machine is positioned and set in motion, the surface of the soil is scanned. The precise location of an asparagus tip is detected by the main controller through the use of laser sensors, together with an additional optical process. A variable number of harvesting modules move in the process round a circular track inside the robot. At present, this consists of twelve of the around 25 centimeter high cassettes. They are adjusted to the speed of the robot and control the entire process of inserting, cutting and gripping.
Fine tuning between target and harvesting module
The controller not only needs the coordinates of the selected asparagus spears to fine tune the harvesting process, but also a continuous flow of information on the position and movement of the modules. This starts with the query of how many cassettes are currently located in the buffer, i.e. how many are in park position, and those currently detecting an asparagus shoot in the circuit. For this AvL uses the tiny BI3-M08K inductive sensors. The exact identification of the harvesting modules is implemented with RFID – using the TN-Q14 HF read/write head, which reads the individual code of each cassette. Added to this is the position detection provided by a rotary encoder.
Inductive sensor triggers a timer
Once a harvesting machine starts its circuit, this passes a type NI10U-M12 uprox proximity switch, which sets the running of the timer for the harvesting process in the PLC. As the asparagus spears do not grow in tidy rows, the harvesting modules can also move left or right in addition to their movement round the circular track. This is driven with compressed air and is therefore always delayed by a few tenths of a second. In order to nevertheless ensure the correct alignment of the cassettes, the PLC obtains information about the distance between the initial and target position of the modules, measured with LE550 laser sensors from Turck's optoelectronics partner Banner Engineering.
Turning maneuver by joystick
Operators use an external control module to control the speed and the hydrostatic steering of the harvesting machine. Two Turck encoders measure the wheel revolutions; AvL uses an inductive linear position sensor to measure the wheel position. For this the positioning element of the LI500-Q25 sensor is linked with the piston of the steering cylinder. In this way, the main controller calculates the angle of both wheels using only one value – and operators can turn the machine easily with a joystick. Unlike the models offered by the competition, farmers do not have to attach the AvL Compact S1560 to a tractor.
Collision Protection on Reach Stackers
Ultrasonic sensors reliably measure the distance between gripper and containers
High Time Pressure at Goods Handling
In large ports and other transhipment points, containers have to be transferred from one means of transport to the next in a short space of time.
Despite the time pressure, however, both the goods and the lifting and loading equipment must be protected. All too often, lifting equipment collides with containers and is damaged, resulting in unnecessary waiting times and costs.
Your Benefits
- Faster and safer handling of goods thanks to collision protection on the gripper
- Two independent switching ranges enable standard and safety speeds when approaching the container
- High vehicle availability thanks to robust sensor in IP67 metal housing
Ultrasonic Sensor Prevents Collisions
Ultrasonic sensors type RU300U-M30E help to protect the gripping devices of the reach stacker during the gripping process of the container. When the gripper approaches the container, the sensor detects the container.
The sensor with a range of 3 metres secures the minimum distance with two independent switching ranges and reduces the approach speed below a specified threshold value to a safe level. This enables the driver to grip and load containers quickly and safely.
Robust Against Shocks and Harsh Environmental Influences
The robust sensor in a metal housing is ideally suited for outdoor use, the plug and sound convertor housing permanently withstand sunlight and temperature changes. The sensor withstands shocks of up to 100 g. Moisture and the salty air in the seaport area also do not damage the sensor. The setting is very simple – either via two teach buttons for each switching range on the housing or by presetting via the teach line.
Print this articleFor more information, please contact:
Ian Manning
Turck Banner Ltd
Blenheim House
Blenheim Court
Wickford
Essex
SS11 8YT
Tel: +44 (0)1268 578888
Email: enquiries@turckbanner.com
Web: https://www.turckbanner.co.uk
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