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FULLY AUTOMATIC SYSTEM FOR PICKING AND HANDLING MUSHROOMS FOR THE FRESH MARKET: FROM THE GROWING BED TO THE COOLING STORAGE

Final Report Summary - CHAMPI-ON (FULLY AUTOMATIC SYSTEM FOR PICKING AND HANDLING MUSHROOMS FOR THE FRESH MARKET: FROM THE GROWING BED TO THE COOLING STORAGE)

Executive Summary:

Champi-ON project has developed a trolley-shaped machine that rolls over the Dutch shelves in search of fresh mushrooms ready to be picked. The trolley is equipped with different subsystems: 1- vision system: selects the next mushroom to be picked, providing other parameters needed by the robotic hand as well (listed later); 2- gripper: a three-fingered robotic hand that grips and uproots the mushroom from the growing bed; 3- stem cutting: a mushroom picked by the main gripper is then handed over to a mushroom management system. From there, the mushroom is lifted by a suction gripper and transported towards the stem cutting mechanism; 4- placement in trays: afterwards, without stopping the movement of the suction gripper, the mushroom is transported and put inside the standardized punnets, where an adjustable shaking mechanism helps mushrooms to be rearranged in the available space inside the punnets.
Project Context and Objectives:
EU SME mushroom growers are struggling to maintain benefit margins due to the globalization of agricultural markets, the increasing cost of raw materials/utilities and the use of outdated and inefficient cultivation methods. As such it is no surprise that fresh mushrooms are often delivered under cost price. As an example, two decades ago there were 1,200 growers in the Netherlands, while today there are less than 200 with an average cultivated area of 2,700 m2. In the future this number is foreseen to drop to 100 large-scale producers with cultivated areas of 10 thousand square meters or more. It is clear that operations of this magnitude need to automate their plants as much as possible to lower the production costs and remain competitive. Furthermore, small growers also need more cost-effective methods; otherwise they are sentenced to disappear.
The white button mushroom (Agaricus bisporus) is the leading mushroom crop worldwide; of the 965 thousand tonnes of these mushrooms produced in Europe in 2007, 60% was sold fresh and the remainder was canned. Whereas for the canned industry mushrooms can be harvested and handled by an automated system (see State of the Art), such automation does not yet exist for picking and handling mushrooms for the fresh market, due to the high quality standards required of this product: all mushroom in a tray should be of similar size and, most importantly, with no damages or blemishes on their snow-white skin. Due to these requirements, hand picking is the only current option for producers, with a cost accounting for between 20 and 46% of their total production costs, depending on the country. In addition, the actual work of picking mushrooms is one of the most physically demanding in the agro sector, given the setup of the shelves and the humidity of the growing rooms, causing high incidences of sick leave in detriment to both the workers and their employers. This also makes it difficult for growers to find people willing to work under such hard conditions.

The Champi-ON project aimed to develop a fully automated system for picking and handling mushrooms for the fresh market. The system has been designed for farms equipped with the Dutch shelving system (consisting in two rows of shelves where mushrooms grow under climate-controlled conditions), because this system is prepared for the introduction of machinery in different steps of the productive cycle; nevertheless, the proposed system could be adaptable in a post-project phase to work with other cultivation methods.

As an end-of-project deliverable, a video has been edited to show non-confidential information of the different parts and performance of Champi-ON trolley, along with an explanation of the Graphical User Interface to control the system. The video showcase has to be uploaded to the “News and Events” in the project website and YouTube (http://www.youtube.com/watch?v=y44MyQ39d00&feature=youtu.be).
Project Results:
The main achievements of the project are presented in the next points:
Gripper system
o Gripper has the ability to conform (within a range) to irregular mushroom cap shapes
o It has the ability to conform (within a range) to potential limited accuracy of the estimated virtual cap centre
o Mushrooms from 38-60mm can be gripped
o Mushrooms gripped are not blemished
o Mushrooms gripped can be uprooted without being blemished (not always such for neighbouring ones) via a coordinated combination of twisting and tilting movements
o Gripper control is easy (on/off valve)
o Gripper weight is low
o Gripper cost is low.

Vision system
A vision system (hardware and image processing algorithms) has been successfully developed and validated, fulfilling the requirements needed by the gripper:
o The hardware (lighting system, camera and actuator to sweep the growing bed from side to side) has been integrated inside the trolley. This design and its implementation were challenging due to the lack of space inside the trolley
o The captured images were processed in a PC embedded in the trolley. This PC was also mastering all the communications and movements of the mechatronic system
o The image processing algorithms selects the next mushroom to be picked, providing to the robotic hand the following parameters: 1- the coordinates of the centre of the mushroom, 2- diameter, 3- positioning angle of the robotic hand by considering free room around the mushroom for the insertion of the three fingers and 4- tilting angle of the mushroom in the uprooting process.

Suction system for handling mushrooms inside the trolley
A mushroom picked by the main gripper is then handed over to the mushroom management system. Then, the mushroom is lifted for further processing by a suction gripper which is driven by a XYZ manipulator:
o Lifting is possible for the whole range of mushroom cap diameters
o Mushrooms are not blemished (even though their final condition could be even better)
o Stability / adherence of the mushroom on the suction gripper during its transport to the next stages of processing is good
o Suction level control is precise and straightforward
o Other vacuum caps can be easily adapted.

Stem cutting system
A picked mushroom is lifted by the suction gripper and transported towards the stem cutting mechanism:
o Design of mechanism resembles the human thumb/knife system
o Cuts are of good quality
o Reliability of mechanism is high, without jams or malfunctions
o Cutting mechanism control is straightforward (on-off valve) and low cost.

Shaking system of the punnets
After having its stem cut a picked mushroom is then transported by the suction gripper inside the standardized punnets:
o Mushrooms are placed inside the punnet for packaging
o An adjustable shaking mechanism helps mushrooms to be rearranged inside the punnet, thus making space for other ones to fit in. This way a better space exploitation is achieved.

The different subsystems have been successfully integrated inside the trolley, both physically and for the establishment of communication among them. The most challenging was the integration of the picking and the vision system, because both share the same area inside the trolley. Collision avoidance has been accomplished by defining safe predefined paths for both systems, and with continuous exchange of positioning data.
Two graphical user interfaces (GUI) have been implemented for two different purposes: 1- for testing the two main sub-systems (vision system and gripper) separately, where the instructions are set manually; 2- for automatic functioning of all subsystems working together, where the user can set the size of the mushrooms to be picked and can get live graphical information about the picking process. This GUI is accessible by WIFI and it offers the possibility of connection to multiple laptops and mobile devices like smart phones.

Potential Impact:
The potential markets for Champi-ON are mostly concentrated in Europe, USA and Australia as they are the largest producers for the fresh market, accounting for a total production of 1,3 million of tonnes (production in China is mainly for the canned industry). Although Champi-ON trolley has been designed for working in farms equipped with Dutch shelving, the system could be adapted for working in other cultivation methods such as French containers.
Since there is not competition in the market, Champi-ON potential impact is very appealing; even though it is quite unlikely that, in a near future, a system can be able to pick automatically all mushrooms in the growing bed, the consortium SMEs consider a reduction of the current labour around 60% a compelling value proposition for mushroom growers. For example, a farm that produces 3600 tons per year needs about 100 pickers, by saving 60% of the labour the same farm would only need 40 pickers; considering that a minimum wage in the Netherlands is about 1400 euro/month, whereas in Poland it's about 500 euro/month, potential savings per year would be around 1.008.000 Euros and 360.000 Euros, respectively.

List of Websites:

www.champi-on.eu