The vibration behaviour of hedgerow olive trees in response to mechanical harvesting with straddle harvester

Abstract

Understanding tree behaviour under mechanical harvesting is very important for orchard management and machine design. The objective of this work is to determine the dynamic response of trees, in a hedgerow arrangement, to a straddle harvester with canopy shaker. Forty-four points were measured in random trees at different heights above the ground. The main vibration parameters in the time and frequency domains were analysed. The transmission range of acceleration between machine rods and trees was 58%, vibrating at a similar frequency of 7.8 Hz. The acceleration values registered in the main direction of rod movement were higher than both in the direction of the hedgerow and vertically. The rods of the harvester are in direct contact with the tree canopy 62% of the tree's vibration time. The resultant acceleration values show a temporal distribution similar to a Gaussian curve but distribution throughout the total vibration time shows that only 49.2% of these values are lower than 50 m s−2 and 93.3% are lower than 300 m s−2. The analysis of vibration time in a range gives more information about the impact of shaking. The tree responded differently at different canopy heights in terms of acceleration RMS and peaks, identifying two zones.