Jakke Kulovesi

New Measurement Concept for Forest Harvester Head

A new measurement concept for cut-to-length forest harvesters is presented in this paper. The cut-to-length method means that the trees are felled, delimbed and cut-to-length by the single-grip harvester before logs are transported to the roadside. The concept includes measurements done to standing trees before felling to calculate optimal length of logs. The modern forest harvesters use mechanical measurements for diameter and length.

Full-Scale Measurements on a Polar Supply and Research Vessel During Maneouver Tests in an Ice Field in the Baltic Sea

Full-scale measurements were performed on the Polar Supply and Research Vessel, the S.A. Agulhas II during ice-trials in the Baltic Sea. Ice loads on the ship hull and propulsion system were measured concurrently with ice-thickness and whole-body vibration comfort for controlled maneuvers in a level ice field. These measurements were aimed at establishing the links between ice-properties, hull- and shaft loads and the vibration feedback received by the operator of the vessel. Results indicate that maneuvers significantly increase the frequency and magnitude of ice loads at the stern shoulder area as well as the ice impacts on the propellers. The number of ice impacts on the instrumented port side shaft line increased for turning maneuvers in a starboard direction. Occupants on the Bridge did not receive feedback through vibration transmission from ice impacts on the hull as a time-history of discrete events. Instead, ice passage excites the global bending modes of the vessel. Blade impacts between ice debris and the propellers are however perceivably transmitted to vessel operators. Although vibration exposure on the bridge is increased by operations in ice subjective experiences of vibration did not reach levels that caused discomfort.Copyright

Motion vision based structure estimation in forest environment

Motion vision can be used to determine world structure from a video sequence. In harvester machine automation, the potential is that trees could be measured from a distance. Based on the measurements, tree cutting could be optimized and harvester automation increased, resulting in higher resource utilization efficiency. However, a natural environment poses challenges to any computer vision task. This paper presents computer vision algorithms that are applied to a forest environment. The results show that dense optical flow can be computed from a real-world forest data accurately enough as to enable instantaneous dense structure estimates of the visible image scene.

Measuring Log Length using Computer Stereo Vision in Harvester Head

Abstract Sales of harvested wood is based on harvester head measurements. Therefore, an accurate length measurement is important when a log is being processed on a forest harvester. A stereo camera pair was mounted to the harvester head and the motions of the harvester head and the log were estimated using off-line machine vision algorihms. Preliminary tests with seven different logs had a maximum error of 12 mm where the mean absolute error between measured and estimated log lengths was 0.09%.