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Development of a novel mechatronic system for mechanical weed ...

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Results and discussion<br />

subassemblies. As main subassemblies the soil with the plants (environment),<br />

the carrier vehicle, the plant detection <strong>system</strong>, the positioning <strong>system</strong> and the<br />

rotary hoeing tool were specified.<br />

During the assembly process, parts were connected to each other using the<br />

same constrains as in conventional prototyping and all connections were<br />

defined exactly like they would be on the real <strong>system</strong>. All parameters which<br />

have not been varied during the simulation process have been locked in, or<br />

constrained, to avoid their move during the simulation. An example <strong>of</strong> this is the<br />

placement <strong>of</strong> the plants on the soil surface. Since an individual plant does not<br />

need to move during the simulation, all six degrees <strong>of</strong> freedom have been<br />

constrained. This can be accomplished, <strong>for</strong> example, by constraining all three <strong>of</strong><br />

its coordinate planes. If a parameters value varies during the simulation, such<br />

as the rotation <strong>of</strong> the hoeing tool, it has been left unconstrained. Its movement<br />

parameters have been defined by simulation motors using the mechanism<br />

design tool.<br />

One <strong>of</strong> the main characteristics <strong>of</strong> the developed hoeing <strong>system</strong> is modular<br />

design. The base is a disk-shaped arm carrier on whose rim different number <strong>of</strong><br />

arm holders can be attached. Typical number <strong>of</strong> arms is 2, 3 or 4. Arm holders<br />

have 3 design variants with 1, 2 or 3 holders <strong>for</strong>ming <strong>for</strong>earms (see Figure 5.6).<br />

Figure 5.6 Design variants <strong>of</strong> the arm holder<br />

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