Heavy-wheeled vehicles with articulated hydraulic steering systems are widely used in construction, road building, forestry, and agriculture, as transport units and tool-carriers because they have many unique advantages that are not available in car steering systems, based on the Ackermann principle, such as—high cross-country mobility, excellent maneuverability, and high payload and lift capacity, due to heavy axles components. One problem that limits their speed of operation and use efficiency is that they have poor directional stability. During straight movement, articulated tractors’ deviate from a straight line and permanent driver correction is required. This limits the vehicles’ speed and productivity. In this study, we describe a driver-aid system concept that would improve the directional stability of articulated vehicles. Designing such a system demands a comprehensive knowledge of the reasons for the snaking phenomenon and driver behaviors. The results of our articulated vehicle directional stability investigation are presented. On this basis, we developed models of articulated vehicles with hydraulic steering systems and driver interaction. We next added the stabilizing system to the model. A simulation demonstrated the possibility of directional stability improvement.
More and more commonly, manipulators and robots equipped with effectors are used to replace humans in the implementation of tasks that require significant working abilities or are used in dangerous zones. These constructions have considerable ranges and are capable of carrying heavy loads. The specificity of the tasks performed with the use of mentioned devices requires their control by a human. Intuitive tracking systems are used to control them. Problems in their use result from the kinematic amplification between the effector and the operator’s hand. Proper design of the drive and control systems for these manipulators requires knowledge of the maximum velocities of the manipulator’s effectors, which significantly depend on the scale ratio. The article presents the results of the effector’s velocity movements while performing a specific task by the operator’s hand with different velocities and scale ratios.
The effective use of robotic manipulators is particularly important when carrying out hazardous tasks. Often, for this type of mission, manipulators equipped with a hydraulic drive system are used, and their work results primarily from the implementation of precise movements through their effectors. In heavy manipulators, limiting the uncontrolled movement resulting from high inertia and relatively low stiffness has an impact on the improvement of the control precision. Therefore, the paper presents experimental studies that allow the assessment of the impact of the use of counterbalance valves on the precision and dynamics of a manipulator with a hydrostatic drive system. The tests were carried out for a wide range of effector velocities along a horizontal trajectory, on the basis of which, it was found that it was possible to improve the precision and dynamics of the work of such manipulators due to the precision of the trajectory and pressures in the drive system.
The efficiency of a skid-steer, all-wheel drive, multiple-axle vehicle with a hydrostatic drivetrain equipped with low-speed motors when it operates on soft terrain was studied. A flow divider enables a single pump to simultaneously power more than one motor circuit with different pressures in each. It prevents kinematic discrepancy and improves vehicle mobility. There are two types of flow divider: spool type and gear type, where each type has its own set of performance characteristics, such as flow range, pressure drop, accuracy and application parameters. In the present work, the influence of the characteristics of both types of flow divider on overall vehicle driveline efficacy is described.
This paper describes FRR wheeled rescue robot which being developed in Robots & Engineering Equipment Team of Military University of Technology. There have been presented also short description of planned to performing by Fire Rescue Robot FRR tasks and caused by them problems to solve. Next have been described the method and model enable to carry out simulation which are necessary to robot suspension system loads identification. Describing developed simulation model, have been presented main used simplification assumptions and method used to calculate main model parameters. The nest paper sections describe the tests which has been subjected to model and examples of their results. In the final part of the paper is a conclusion and discussion of the results of research.
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