Automation - Replacing muscle power

Automation and robotics are revolutionising horticultural production. Professor Geoff Dixon looks at the latest developments.

GPS guidance: controlling antennae mounted on tractor chassis to measure and control the vehicle’s movements - image: Manterra
GPS guidance: controlling antennae mounted on tractor chassis to measure and control the vehicle’s movements - image: Manterra

Reliance on unskilled manual labour by horticulture is ending. Investment in automation and robotics, while initially expensive, is ultimately more cost-effective. Machines continuously perform repetitive tasks accurately for as long as they required to do so. Electronics deliver better quality control, benchmarking and long-term records. Examples provided by British and European engineering companies show what is possible.

Weed control

The loss of many herbicides has speeded the uptake of automated weeding. Leading this change is Garford Farm Machinery of Deeping St James in Peterborough with its Robocrop systems. Computers in the tractor cabs collate and compare images captured by digital cameras. Early models identified crop rows and automatically aligned cultivators in parallel between them.

This concept came from Tillett & Hague of Wrest Park Silsoe and was exploited by Garford. Continuing research and development produced computerised control that compares images of crop plants and weeds and then synchronizes the rotation of cyclical cultivating discs, which eliminates unwanted plants within and between each row.

Cultivation works at up to two plants per second per row, requiring the use of several cameras feeding images into the computer. Garford machines control 18 rotor units simultaneously using three cameras. Ease of operation is achieved with front-, mid- and rear-mounting on the tractor. Hand weeding in transplanted crops such as headed lettuce and brassicas is eliminated.

GPS-guided cultivation

An alternative to digital cameras is the use of GPS (global positioning system) guidance, control and recording. This uses geostationary satellites in a similar manner to a vehicular satnav. Initial technology for GPS self-steerage systems of crop cultivation was developed by the SBG Company in Wageningen, the Netherlands. In the UK, it is sold by Manterra in York.

The satellites provide primary reference sources by radio signals and these are collected through a base station named 2009 Geostar Terminal. In turn, that locates and controls field machinery working anywhere within 10km through antennae fixed onto the tractor with an accuracy of +/-2cm.

Since UK terrain is more undulating than Holland, a Smartbase Mobile Base Station is recommended for delivering reference points between the satellites and farm machinery. These are mobile and can be placed anywhere adjacent to field cultivation. Controlling GPS antennae are mounted on the tractor chassis. This measures and controls vehicle movements, recording wheel positioning and hydraulic settings operating the steering.

Mounted machinery is controlled using separate tracking and integrating GPS systems set on the tool bars. Computers store this data and the position of individual plants within crops for subsequent year-on-year operations. Initially, the system controlled ploughs, preventing tractors going off-line, achieving the correct furrow width. More recent developments provide control of hitched and towed implements for drilling carrots or planting potatoes. This uses a twin-steerage system controlling both the tractor and implements. Further research aims at applying and recording spraying.

Fertiliser placement

Automated camera sensing of fertiliser distribution and monitoring produced the N-Sensor from Yara, based in Grimsby. This uses digital optics identifying variations in crop colour, comparing green healthy foliage with yellowing and chlorosis elsewhere. Reflectance data taken from crop canopies are then interpreted into the variable application of nitrogen fertiliser based on known crop requirements. The spectrometers, fibreoptics and processing electronics controlling and recording fertiliser distribution are mounted on top of the tractor cabin.

Application in horticultural crops started in 2010 with cauliflowers grown by PE Simmons & Son farms in West Cornwall — they grow a range of brassicas specialising in cauliflowers. David Simmons crops year-round and uses more than 60 cultivars, each with a defined maturity period for markets where quality, consistency and continuity are essential. Variations in yield and maturity result from differing soil types ranging from sands to heavy clays.

Yara's N-Sensor ALS (active light source) offers precision fertiliser distribution based on actual crop need. The N-Sensor ALS copes with the low light conditions found during winter in western Cornwall. David Simmons showed that "by varying the rate of nitrogen around a target dose, the N-Sensor improved yield and quality using less fertiliser". This system also gives computerised traceability, accurate records of fertiliser use and biomass maps supporting quality assurance demands.

Automated harvesting is the Holy Grail for field crops. It would remove the need for manual labour working in frequently unpleasant conditions. The Horticultural Development Company and the Production Engineering Research Association tried this unsuccessfully for brassicas. Indications are that Far Eastern research may prove more successful. Korean studies, for example, report successful lettuce harvesting at five seconds per plant.

Post-harvest operations

Automation post-harvest must cope with varying colours, defects, sizes, shapes, volumes and densities in tough environments. Technologies being rapidly applied include machine vision, near-infrared radiation, X-ray, acoustic response and 3D machine vision.

Hydro-coolers are essential for rapidly removing field heat from crops prior to sorting and packaging. Tickhill Engineering Company in Doncaster has automated this operation. Its machines are manufactured in stainless steel with insulated panels that maintain optimum temperatures and with modular belts transporting the produce. Stainless steel cooling coils chill the water to around 1°C that then passes among the vegetables and brings down their core temperature, then the water is filtered and reused automatically.

Tickhill launched a new vegetable polisher in 2011 that has many advantages over belt-driven machines. Clever engineering allows roller removal within minutes through a cartridge-style bearing mechanism and special drive couplings, resulting in very low maintenance costs and minimal downtime during servicing.

The design and manufacture of automated handling and sorting equipment for the vegetable industry is a speciality of Tong Engineering in Spilsby, Lincolnshire. Its most recently designed machines feature electric motors driving every individual shaft, ensuring careful control of cleaning operations, gentler handling of the crop and guaranteeing minimal maintenance.

Reduced electricity use is achieved by direct-drive mechanisms applied to Tong's new Easy-Clean System. Additionally, this technology is available with touchscreen controls. These provide total management control when changing the machine's settings so allowing for differing crop types and their cleaning requirements. "With more than 80 years of engineering experience, Tong Peal continues providing its customers with the latest market innovations in grading, washing and handling crops," said export manager Charlie Rich.

He continues: "We are committed to developing new equipment to really meet the changing needs of growers and packing-house professionals, helping them to reduce their energy consumption, minimise their labour costs and increase throughput while still ensuring gentle and efficient handling of the crop."

These machines incorporate Tong Peal's "in touch" technology. As well as touchscreen controls, this includes memory settings, email or text alerts and remote diagnostic access. Tong Peal's system now allows operators to store settings in the machine's memory. The speed and direction of rollers and conveyors can be changed at the touch of a button to any combination of predetermined adjustments, programmed for specific crop conditions and cleaning requirements. Users can simply set the machine once and store that particular combination, which can be password protected.

"In the unlikely event of a fault occurring on the machine, if it is fitted with our remote diagnostic module, our technical team can make access remotely to the control panel assisting with tuning, making adjustments, resetting it completely or identifying the problem so that a fully briefed engineer can visit the machine and resolve the problem very fast," Rich explains. "That provides big savings in time and money. Remote access allows the resolution of problems even faster than we do now."

Breaks in processing produce post-harvest cause expensive delays in harvesting at one end and in meeting delivery schedules for supermarket customers at the other. Downtime can seriously damage a company's image. For this reason, mobile and email alerts complete Tong Peal's most recent advances. Should any faults occur with a machine, it will trigger an automated warning that will be issued via email or text message to a contact number of the customer's choice. These new features save time and money, and result in better-quality produce.

Professor Geoff Dixon is managing director of GreneGene International.


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Professor Geoffrey Dixon

GreenGene International chair Geoff Dixon on the business of fresh produce production
 

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