Koen Deprez

Comfort improvement by passive and semi-active hydropneumatic suspension using global optimization technique

The arising health problems of operators of off-road vehicles point out that still a lot of effort has to be put into the design of effective seat and cabin suspensions. The comfort problem originates form the vibrations transmitted to the driver caused by the unevenness of the road or soil profile. The paper develops a method for optimizing suspension systems using the global optimization technique DIRECT. Evaluation of the comfort improvement of the suspensions is done using the objective comfort parameters used by the norms. The design procedure is tested on a hydropneumatic suspension that can serve as a cabin suspension for off-road machinery. The evaluation shows that the vibration levels can be reduced by 90%, resulting in a drastic comfort improvement.

Development of a smart mass flow sensor based on adaptive notch filtering and frequency domain identification

A popular method for measuring mass flows of granular materials is to register the induced force on a circular chute. When properly designed, an accurate, friction independent and linear flow measurement is achieved, ready to install in agricultural machinery or process lines. Since this type of sensor is strongly subject to wear and is installed in inaccessible places, it is important to know when it provides wrong measurements without interrupting the process. In this study, an off-line frequency domain procedure is designed to estimate wear on the chute suspension based on normal grain flow variations without extra excitation devices. The uncertainty bounds on the dynamic parameters are iteratively estimated based on a non-linear transformation between the parameter and pole/zero space. As an alternative, a robust and stable method is presented to track the resonance frequency of the mechanical sensor and paddle rate of a feeding elevator on-line.

Prediction of spreading processes using a supervised self-organizing map

A novel technique is presented based on self-organizing neural networks for prediction of fertilizer distribution patterns of spreaders as a function of spreader settings and fertilizer properties. The main aim of the presented technique is to predict tendencies in the spreading distribution pattern as a function of machine configurations and physical fertilizer properties. The Self-Organizing Map is used in a novel way to represent input–output relationships between high-dimensional spaces. Other NN methods would be very difficult to use because of the high dimensions of the input and output spaces. In the case of a multilayer perceptron, the global connectivity would lead to a prohibitively large number of free parameters giving rise to learning time problems. The spreading distribution patterns are predicted with a high performance with the proposed technique.

Design and Evaluation of a Low-Power Portable Test Rig for Vibration Tests on Mobile Agricultural Machinery

Increased capacity of mobile agricultural machinery and higher driver comfort requirements force manufacturers to incorporate dynamic behavior explicitly into the design. Therefore, vibration tests should be carried out during the design phase. Because many of these manufacturers are small, they lack the know–how and equipment to perform these tests. Transportation to and from specialized companies to evaluate the vibrational characteristics is costly and time–consuming because of the size and weight of most agricultural machinery. A low–power mobile electro–hydraulic shaker allows such analysis to be performed on the factory floor. Such a device can be created by putting an air spring parallel to the actuator of an electro–hydraulic shaker, resulting in considerable power savings. A shaker with and without a parallel spring is theoretically examined. Experiments on a one–degree–of–freedom vertical shaker showed good agreement with the theory and demonstrated that different mode shapes of an agricultural tractor can be sufficiently excited with a nominal hydraulic power of 500 W.

COMFORT IMPROVEMENT OF AGRICULTURAL VEHICLES BY PASSIVE AND SEMI-ACTIVE SUSPENSIONS

Abstract Growing awareness that uncomfortable agricultural vehicles endanger the health of the operators and stricter norms concerning this, make the design of an effective cabin suspension inevitable on agricultural vehicles. The comfort problem originates from the vibrations transmitted to the driver caused by the unevenness of the road or soil profile. This paper investigates the effect a passive and semi-active cabin suspension has on the comfort of the drivers. By optimizing the parameters of the passive suspension and those of the semi-active control laws, satisfactory improvement of the comfort can be achieved.