Robotic harvesting in the open field demands innovative solutions in robot perception and mechanics to cope with environmental challenges. In this paper, a prototype robotic harvester that is able to cope with the challenges of selective harvesting of green asparagus is presented. The harvester is able to drive along an asparagus dam in the field, detect asparagus stalks, identify stalks that are ready for harvesting, and perform harvesting without damaging. These system abilities are enabled by a novel vision perception module and a novel harvesting mechanism. The perception module is based on three-dimensional-point cloud processing, and it is able to reliably and robustly detect the asparagus stalks, their positions, and dimensions. A novelty of the proposed harvesting mechanism is a multi-tools solution to increase harvesting productivity. The results of the first outdoor field tests demonstrate the applicability of the presented robotic harvester.

FE simulation was applied to study the material flow during infeed rotary swaging. The neutral plane according to the process parameters was investigated and compared with experimental results. A single forming stroke was analyzed precisely by using small time points of 10-4s. For analysis the essential steps between the first contact of wire and forging die and the last contact before the die opens again are represented. In that range the feed velocity is eliminated and the neutral plane can be observed as spatial velocity at nodes in the axial direction equal 0mm/s. During a single stroke the location, the geometry and the orientation of the neutral plane is changing

Rotary swaging is a cold bulk forming process. The diameter of the workpiece is reduced incrementally by oscillating movement of the tools. The established processes use lubricants which fulfill necessary functions such as lubricating, cooling and cleaning of the tools. Disadvantages caused by the use of lubricant are costs of recycling, replacement of lost coolant and for the cleaning of the workpiece. To eliminate the lubricant it is necessary to substitute the functions of the lubricant in other ways. For example by means of coating and structuring of the tools.In this study infeed rotary swaging with structured tools is investigated using finite element simulations. Different structures are implemented in the reduction zone of the tools. The influence is investigated by the radial and axial process forces. Additionally first structured tools are manufactured and experimentally tested. The results of modeling and testing are discussed

Infeed rotary swaging is a cold forming production technique to reduce the diameter of axisymmetric components. The forming is achieved discontinuously by a series of radial strokes that are spread over the shell of the part. Due to tolerances within the rotary swaging machine, these strokes perform individually and the resulting stroke pattern is not homogeneous with regards to circumferential and longitudinal distribution. Nevertheless, in combination with the high number of performed strokes and the large contact area between the dies and the part, the external part properties, such as diameter, roundness and surface roughness, show even values along the finished part. In contrast, strength-defining internal part properties, like microstructure and residual stress components, are more sensitive to the actual pattern and temporal sequence of the individual strokes, which is investigated in this study. The impact of process fluctuations during the conventional process, which are induced by the tolerances of machine tool components, was verified by numerical simulations, physical tests and measurements of residual stress distributions at the surface and at depth. Furthermore, a method is introduced to maintain the stroke following angle ∆φ at zero by flat dies, and thus the actual pattern and temporal sequence of the strokes was homogenized. The results show that the residual stress fluctuations at the surface could be controlled and reduced. Furthermore, it is demonstrated that the depth profile of the residual stresses at a distance of 300 µm from the surface developed independently from the process fluctuations.