M.Sc Thesis

M.Sc StudentHikind Yuval
SubjectA Man-Machine Interaction Model to Determine the Safety of
Devices for Harvesting at Heights
DepartmentDepartment of Civil and Environmental Engineering
Supervisors PROFESSOR EMERITUS Itzhak Shmulevich
PROF. Dror Rubinshtain
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


The main goal of this research was to develop a model of man-machine-environment interaction to determine the safety of platforms for harvesting at heights.

Afron type SA500 is an agricultural machine designed for working at heights up to 5m in orchards, with a limited stability platform. Over the years, some rollover accidents of the Afron have been reported. New regulations require all operators of all types of high-altitude mobile platforms to be hitched by a safety harness to the platform. Operators from the agricultural sector claim that adopting these regulations may increase the risk involved in operating the Afron-type platform. The purpose of this research was to investigate the contribution of the new regulations to the safety of Afron operation.

A multi-body dynamic model of the Afron platform was developed using LMS Virtual Lab software. Computational simulations were performed to study the possible roll-over scenarios. The results indicate that roll-over cases may occur on different conditions. The human model of the Madymo program (midsize male pedestrian) was selected to represent the operator, the environment, and their interaction. The roll-over path was imported into the model. A contact force model developed between the operator and the soil were experimentally examined. Harness models were represented by finite element method and multi body model.

 During roll-over, the operator may jump out of the platform cell. In order to model jumping possibilities, experiments were performed to define the leg-joint kinematics during the jump. Several simulations were examined by jumping at several different platform angles and with belted and unbelted operator conditions. Simulations of free fall were performed to represent an operator who may be caught on a treetop during roll-over and lose his hold. Other human reactions to roll-over situations were simulated. Injury criteria (head, neck, thorax and tibia) used by the automobile industry to estimate vehicle safety were estimated. These injury criteria were weighted to evaluate the total injury severity for the simulated scenario.

The simulation results provide no indication that a belted operator has an advantage in terms of severity safety compared with an unbelted one. In fact, belted operators have an advantage over belted ones because they can be rescued by getting caught on a treetop. The method developed in this research may be adapted to other field machinery.