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Incorrect inflation pressures in tyres affects the vehicle handling, passenger comfort and braking conditions in addition to causing a reduction in fuel efficiency and tyre life. To address this problem, mathematical models have been produced and an experimental validation has been carried out. The models were developed with 7-DOF, for a full car system, using MATLAB programs. In the simulation study, the suspension faults have been considered by running the models with a range of inflation pressures at four conditions i.e. at standard pressure (2.3bar) and 1.5bar on the passenger wheel, driver wheel and front wheels. In each case, an analysis was carried out on the performances of the suspension in terms of ride comfort, road handling and stability of the vehicle followed by the presentation of the results obtained. In addition, the influence of parameter variations on transfer functions as a fault detection of suspension has been introduced. This approach has been used when detecting faults of vehicle tyres being under-inflated 35% and also to detect other suspension faults in the future.

Purpose of research. Currently, exoskeletons are getting widespread use. They enhance human capabilities in terms of ease of movement, carrying loads and different types of activities that require considerable effort. Especially effective are those exoskeletons that make it possible to make complex types of movement of both for the lower and upper limbs, which significantly expands the capabilities of a person when performing loading and unloading operations. Relatively recently, they have started the development of exoskeletons which use the elements of gravity compensation. Therfore, the study of energy costs in the process of load lifting and the study of gravitational compensators influence on the magnitude of moments made by the electric drives of the femoral and knee joints, is relevant and is revealed in this paper.Methods. Methods of system analysis, design of biotechnical systems, control theory, theory of mechanisms and machines, methods of mathematical modeling of dynamic systems, methods of optimal planning and design were used to solve the problems. Mathematical packages Matlab/Simulink were used to make software products.Results. The study shows that the use of gravity compensators can significantly reduce the load on electrodrives. The movement of load is due to the operation of engines located in the area of ankle, knee and thigh joints. Since the movement of the exoskeleton occurs in the sagittal plane during load lifting, the position of the exoskeleton links in space is determined by four independent parameters.Conclusion. The mathematical model of load lifting by a man in an exoskeleton has been developed. Mathematical modeling of the process of load lifting with the help of exoskeleton electric drives has been made. A special attention is paid to the study of gravitational compensators influence on the magnitude of moments created by the electric drives of femoral and knee joints. It shows that the use of gravity compensators can significantly reduce the load on electric drives. Also, the study of energy costs in the process of load lifting has been conducted.

Suspension system has significant influence on the passenger safety, providing comfortable ride, stability, and handling of the vehicle. The aims of the present research are to investigate and quantify the effect of spring weakness on suspension performance. This is based on a MATLAB simulation analysis of a seven degree-of-freedom (7-DOF) model for a full vehicle. In the simulation, the suspension faults were seeded by reducing the spring stiffness by 25%, 50% and 80%. The model was validated using experimental data, collected by driving the vehicle across bumps. The simulation results for varying degrees of spring stiffness indicated that the ride comfort was decreased as the spring stiffness was increased for excitation frequencies close to resonant frequencies of the vehicle body (approximately 1 Hz). As spring stiffness was increased at excitation frequencies below 1 Hz, the suspension travel was reduced. Within the zone of resonant frequency of sprung mass, the deformation amplitudes were increased as the spring stiffness increased. Moreover, Frequency Response Functions analysis has been used for fault detection of reduction of spring's stiffness by 25%, 50% and 80%.