The challenge Modern floriculture is a lot different than in your grandmother’s times when everything was done by hand . Nowadays, fully automated machines with digital cameras have come into operation because the demands on the processing time are becoming increasingly higher. To facilitate the growth of the plants they have to be planted from a smaller cell (pot) into the next largest cell (pot) in specific time intervals. This process is called “piquing”. It is imperative however, that the young plant is not damaged during this process. A plant bin can contain up to 512 cells and it is essential that they be replanted in the shortest time possible using a fully automated machine. But prior to this process, a camera has to identify and check the position of the bin to see if the cells are full or empty. During this operation, the camera must simultaneously determine if the plants have reached the proper growth height and have the correct color as a bin must always have the same color or a specific pattern. To replant several thousand plants per hour, speed and precision are critical factors.

The ingenious idea of a gripper that can grasp the delicate seedlings came from Den Hartigh. “The gripper mustn’t damage the stalk. This problem was solved using a rod underneath the seedling that slightly raises the root ball as the gripper is lowered. As soon as the gripper lifts the seedling, the rod returns to its starting position. A simple, but a very effective improvement which avoids damage to the plant material.” The TTA fixer is a fully automated planting machine used for loading the cells with plant materials. The cell is first scanned with a vision system so that the machine knows which cells are empty, then the seedlings are planted by the gripper. 
 
When used in conjunction with the TTA blowout system, a superior level of precision is achieved; an advantage that is seen in the event of contamination or processing very big plants. First the plants are scanned with a digital camera from the TTA vision system, then individual parameters of a cell such as height, color or position of the plants, can be individually adjusted. The male plants have only one blossom while the female plants have several. A few weeks after sowing, there is a minimal color difference that is detected by the “progressive scan” vision camera. After selection, the male plants they are blown out of the cell from below using an air pressure nozzle. “Our solution is a combination of the vision system and a plant machine, which greatly improves earnings.”

50.000 plants per hour

The piquing process deals with huge quantities. This can be seen by the enormous capacity of a fully automated transplanting machine . The machine type, TTA-PRE, is designed for use in middle-sized and large businesses . It can be optionally equipped with 16 to 64 plant grippers and has a capacity to process between 12,400 and 50,000 plants per hour. Each plant gripper is controlled by an individual microprocessor with a corresponding servo drive. Using this technique, the TTA-PRE is able to plant in any pattern imaginable.

Gantry principle To meet the steadily rising demands on the machines for speed, a drive system was developed which enable the grippers to move in a smooth, flowing curve. Unlike the jerky, non-smooth motions, typically inherent with using “simple” controls . Using the so-called Gantry-principle, two fixed servomotors drive two axes (Y and Z) over a single belt. This results in the extremely dynamic Gantry motion. Another additional servo drive is available for the less dynamic X-axis, which only sets the (adjustable) distribution of the grippers. DIAS-PLC-system – quicker and more precisely At the beginning of 2001 the existing PLC system was replaced by the DIAS-PLC system, which uses the programming tool LASAL Class. The most important results of this change in conjunction with the Gantry-principle was an increased system speed of 25 to 30%, a positioning accuracy of 0,5 mm and improved software reusability due to the object oriented programming approach.  A further advantage of the DIAS system is that the HMI, PLC and Motion Control are integrated in the DTC 281 operation terminal with various DIAS modules connected in a decentralized configuration. The complete DIAS system is a sort of virtual motherboard by which the various stations on the DIAS bus communicate in the same manner as modules that sit next to each other. Instead of a fixed module mounting on which various I/O modules are connected, the DIAS system acts like a so-called functional unit, consisting of a function modules (digital and/or analogue I/Os, positioning modules, servo modules, etc..) and their corresponding terminal connections, on which the entire field of cabling is attached. Therefore, additional connection terminals are no longer necessary.  An advantage of the LASAL programming software is that the CPU time can be partitioned and prioritized according to the requirements of the application; a CPU time slot can be defined for every task. The “Gantry“ drive features a “Real-time” section for the servo technology of 2 ms, 10 ms are reserved for the cyclic PLC tasks and the remaining CPU time is available for the less important tasks such as the visualization.