The application of advanced robotic technology to horticultural production is a relatively new concept. Not so long ago it was still that oft-quoted cliché ‘blue-sky thinking’. But its introduction on a widespread commercial scale is getting ever nearer.
But what exactly are we talking about when we use the term robotics? Automated systems are nothing new, of course. In the first part of this series two weeks ago, Commercial Grower examined the introduction of the systems mostly used in glasshouses to obviate the monotonous, repetitive, low-level chores requiring little or no decision-making capabilities that had been formerly undertaken by human workers.
Growing, however, cannot be reduced to the fabrication of multiple, exact-specification components. Human-like decision making capabilities are still necessary. And that is where more advanced robotic technology comes in.
For some time now the agricultural technology and engineering departments of colleges and universities around the world have investigated ways of creating technologies which can take some of the decision-making responsibility and handing it over to machines, thus saving growers time, effort and money. So what is the state of play with robot technology aimed specifically at the farm sector and the horticulture sector in particular?
Professor Richard Napier, of Warwick HRI, has long been associated with work in this particular field. He said the glasshouse and bedding plant sectors are well catered for in terms of robotics. For instance there are machines that tend plants from seeding right through to almost the finished product. There are many image processing projects going on. Video imaging enables real-time assessment of the plants. Stereo imaging enables 3D pictures to be taken of the plants, giving, as it were, an ‘all-round’ evaluation of a crop’s state. Growers are able to use such technology to get the plants ready for when they are needed. Napier said these sorts of aids build in a ‘whole level of autonomy as to how plants are grown’.
One of Warwick HRI’s most talked about innovations is the robotic mushroom picker which received a good deal of press attention internationally. Developed by engineering doctorate student Jim Rowley, the picker imitates the actions of a human worker. It uses a vision system to select the right sized, healthy mushrooms from trays. The system pin-points the co-ordinates of the mushroom and then sends a message to a robot controller which uses a laser to estimate the mushroom’s height. The picking is done by suckers on the end of an arm and the mushroom placed in a receptacle.
One of the main drivers for this research was the worsening competitive position of Britain’s mushroom industry against that of Europe. Rowley reckons automation of this type could reduce production costs by eliminating harvest labour. The work is sponsored by the HDC.
Rowley hopes there are added possibilities for wider applications throughout horticulture and other industries.
Napier meanwhile says the mushroom picker could be prepared for the commercial market in a couple of years. There is one caveat, however: “It is not the sort of robot that can be used in a standard mushroom tunnel. To use it effectively growers have to invest in modern mushroom warehouse systems. It needs a complete growing system to make the robot financially viable.
“Whether the industry, at least in the UK, has the capacity to take that forward remains to be seen.”
Another Warwick HRI project, almost ready for market, is an automatic hoe for field-scale work. Dr Andrea Grundy heads the team that developed the hoe system. It too uses an image analysis system which is front mounted on a tractor. It images each individual crop plant. The hoeing work is done by reciprocating arms on the front.
Grundy told Commercial Grower there has been a lot of commercial interest in the machine despite the main aim of the project to create a protoype only (a demonstration was due to take place Tuesday this week). The project was undertaken with a consortium which included the engineering firm Tillett & Hague.
Napier says that ultimately the robots are being investigated in order to reduce labour costs. For example, the mushroom picker can work 24 hours a day, seven days a week. The hoe has other benefits in that it could help reduce pesticide applications and is therefore good for the organic market.
He says: “Mechanisation controls consistency, quality and reliability. The robots are not subject to human error. They work to a set of rules. For all these reasons robots are attractive.”
Commercial production of robots does have a few snags, according to Napier. For one thing, robots are not designed to work outside in all sorts of harsh conditions. They must be ‘ruggedised’, in Napier’s words. Another thing is a constant, steady power supply for the machines has yet to be developed.
Another drawback, at least for growers suspicious that investment in the new technology will see a return worthy of the name, is that to utilise the robots, in many cases, the whole growing system needs overhauling. We have already mentioned new warehousing for mushroom tunnels need for the robotic picker. Technology has yet to catch up with the safety implications of unsupervised tractors working in fields.
Napier says that, for instance, it would be perfectly possible to come up with a machine that robotically picked strawberries. But that would probably entail developing a strawberry plant/variety and a growing system which produced fruit in a position in which a machine could pick it easily. This would most likely have to be in a glasshouse environment and could mean large investments.
He also mentions a project by Richard Pearson Ltd and United Vegetables looking into the robotic harvesting of cauliflowers. He says the companies have investigated developing varieties with longer stems which would help the automatic harvesters cut while reducing wastage.
It seems that the application of robotic technology to horticultural businesses requires compromise, lateral thinking and a good deal of investment. Although growers do not seem to be queuing to spend money in this area it may not be long before labour costs and the imperative for efficiency drive them in that direction.
However, the advent of the day when a grower can twiddle his thumbs in the office while his business is run entirely by robots is still a little way off.
“There will be incremental improvements on all fronts of automation. But there’s a lot of development to do until we get completely independent machines,” says Napier.
Work by agricultural machine manufacturers Richard Pearson and growers United Vegetables has looked into ways of estimating different sizes and positions of cauliflower curd when they are hidden by leaves.
Manual harvesting methods rely on a ‘slaughter’ harvest, taking all the plants in one pass and accepting the loss in crop value when some plants are lifted too early or too late.
Pearson and United worked with 3DX-RAY Ltd to find a more economical and less wasteful way of lifting and trimming cauliflowers ready for the supermarket shelf. 3DX-RAY was asked to investigate ways of automatically identifying which growing cauliflowers were of the optimum size, and how to control the cutting heads to crop and later trim the vegetables.
The prototype system used 3DX-RAY’s 2DX-Camera. As the unit is towed along a row of plants, an x-ray imaging processor identifies which cauliflowers are ready for harvesting. Once cut and lifted on-board the harvesting equipment, the cauliflowers pass a second x-ray camera that locates the top and bottom of the curds so that the trimming knives can prepare the vegetables for the supermarket shelf. Size selection, cutting, lifting and trimming are all completely automated.
Advantages claimed for the procedure include: reduced labour cost, minimal wastage, and floodlighting not required for harvesting in darkness. By harvesting at night growers can take advantage of lower temperature to reduce refrigeration costs, the plant is biologically ‘shutdown’, and product shelf life is extended.
Development of the automatic hoe was driven by diminishing herbicide options, fear of ground water contamination and customer pressure to minimise herbicide use. However, product contamination concerns entail high levels of weed control and have resulted in increasing use of time and money-consuming hand weeding.
A major constraint to continued growth of processed bagged salads is contaminants. Major contaminants are weeds and weed seeds, however other pest and disease contaminants are enhanced by poor weed control.
The majority of salad crops are hand weeded once and some twice at a cost of £400-£1,000/ha. Brassica production is also affected by weed contamination.
It is estimated that only five percent of brassica crops currently require hand weeding. Most organic brassica crops are hand weeded and costs are lower at around £100 - £250/ha because of wider plant spacing and a greater tolerance to weeds.
Weeds growing within crop rows continue to be the major problem because of gaps in the herbicide control of certain weed species and the close proximity of the weeds to the crop making conventional mechanical weeding difficult without risking crop damage.
Researchers spotted an opportunity to develop an adaptable, cost-effective technology for mechanically controlling weeds, specifically in-row weeds, for a wide range of brassica and salad crops that would enable machinery to control in-row weeds mechanically. They believe such a development would increase UK industry competitiveness in a way that is sustainable in a low herbicide environment.
The scientific approach of this Defra sponsored Horticulture LINK project was to develop fast, two dimensional mathematical template matching techniques, which enabled individual crop plants to be located while coping with crop spacing variability. Researchers wanted to develop a system which allowed regular observations of plant position to be passed to a tracking algorithm that followed plant location from a moving vehicle thus enabling weeds to be removed from between crop plants and leaving the crop undisturbed.
Anticipated benefits to be gained from the project were chiefly environmental resulting from reduced herbicide use as well as lower mechanical weeding costs which would increase potential for organic production. Reducing the number of weeding operations through better targeting may help minimise problems caused by frequent soil disturbance.
Other benefits included improved plant location which may further improve existing inter-row guidance, further reducing herbicide use.
The project is sponsored by the Defra Horticulture LINK Programme. THT acted as sub-contractors to Warwick HRI delivering the engineering research aspects. The project has the following additional industrial partners:
Robydome Limited
Garford Farm Machinery
Edwards Brothers
Robert Montgomery Limited
Allium & Brassica Centre
AGCO.
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