MODELING THE OPERATION OF A RECUPERATIVE SPRING-HYDRAULIC FIFTH-WHEEL COUPLING LOCATED IN THE SEMITRAILER OF LUMBER TRUCK

The substantiation of the necessity of using timber trucks, consisting of timber tractors with semi-trailers, when transporting timber, is given. Attention is focused on improving the efficiency of the functioning of log trucks by con-structive improvement of the fifth-wheel couplings used in them. The analysis of scientific works of foreign scientists engaged in the study of the influence of fifth- wheel coupling on the efficiency of log trucks is carried out. A promising scheme of a recuperative spring-hydraulic fifth-wheel coupling, located in the front part of the semi-trailer frame of a timber tractor, is proposed, which has significant advantages in comparison with other similar devices. At the first stage, a mathematical model of the proposed fifth-wheel coupling was developed; at the second stage, a computer program for a preliminary assessment of the efficiency of the functioning of a timber tractor with a semitrailer equipped with a recuperative spring-hydraulic fifth-wheel coupling is made. The dependences of the change in the average values of the recuperative power and longitudinal acceleration of the trailer relative to the timber tractor on the inner diameter of the hydraulic cylinders of the recuperative device, the mass of the semi-trailer and the frequency of braking and accelera-tion of the timber road train are obtained. It was revealed that the optimal diameter of the hydraulic cylinders of the recuperative device for the given conditions, providing the maximum recuperative power, should be in the range of 50-60 mm. It was found that with an increase in the mass of a semitrailer of a logging tractor, as well as with an increase in the frequency of braking and acceleration, an increase in the recovered power is observed

A new physical pattern – consistency of the factor of dynamic relations between velocity vector modulus and longitudinal acceleration of missile warheads

The paper describes the existing problems in determination of all scheduled evaluations of missile warhead performance during flight tests and puts forward one of the possible methods of problem solving. Besides, the paper gives the results of investigation of the properties of the factor of dynamic relations between the velocity vector modulus and longitudinal acceleration of missile warheads within the atmospheric passive flight leg – the dynamic relation factor is constant in different flight test conditions. The notion of the reference dynamic relation factor is reasonably introduced for both parameters under study in order to provide reliable determination of parameter estimates, and hence, to conduct a complete analysis of experimental launch results.

Development of Algorithms for Performance Index-Based Actuator Fault Detection and Fault-Tolerant Control of Autonomous Vehicle With Adaptive Feedback

This study proposes algorithms for performance index-based actuator fault detection and fault-tolerant control with adaptive feedback. Longitudinal control algorithm of autonomous vehicles is generally divided into three main parts such as supervisory, upper level, and lower level controllers. In the supervisory controller part, desired behavior is determined based on control targets. Therefore, desired vehicle motion such as longitudinal acceleration can be designed in the upper level controller part using various control methods. In the lower level controller part, actuator control input is determined for tracking the desired vehicle motion designed in the upper level controller part. In order for fault detection and fault-tolerant control of actuators used for longitudinal autonomous driving, adaptive feedback controller has been designed with the MIT rule for determination of the desired longitudinal acceleration and the control input has been compared with the actual acceleration for performance index-based fault detection. It is designed that the adaptive feedback controller adjust the desired acceleration for making reasonable desired behavior despite of existence of actuator fault or performance degradation. The window-based weighted standard deviation of error between the adaptive desired longitudinal acceleration and current acceleration of vehicle has been used for computation of performance index. Performance evaluation has been conducted using Matlab/Simulink and commercial software (CarMaker).

A Novel Longitudinal Speed Estimator for Four-Wheel Slip in Snowy Conditions

This article proposes a novel longitudinal vehicle speed estimator for snowy roads in extreme conditions (four-wheel slip) based on low-cost wheel speed encoders and a longitudinal acceleration sensor. The tire rotation factor, η, is introduced to reduce the deviation between the rotation tire radius and the manufacturer’s marked tire radius. The Local Vehicle Speed Estimator is defined to eliminate longitudinal vehicle speed estimation error. It improves the tire slip accuracy of four-wheel slip, even with a high slip rate. The final vehicle speed is estimated using two fuzzy control strategies that use vehicle speed estimates from speed encoders and a longitudinal acceleration sensor. Experimental and simulation results confirm the algorithm’s validity for estimating longitudinal vehicle speed for four-wheel slip in snowy road conditions.

Assessment of the Energy Consumption and Drivability Performance of an IPMSM-Driven Electric Vehicle Using Different Buried Magnet Arrangements

This study investigates the influence of the buried magnet arrangement on the efficiency and drivability performance provided by an on-board interior permanent magnet synchronous machine for a four-wheel-drive electric car with two single-speed on-board powertrains. The relevant motor characteristics, including flux-linkage, inductance, electromagnetic torque, iron loss, total loss, and efficiency, are analyzed for a set of six permanent magnet configurations suitable for the specific machine, which is controlled through maximum-torque-per-ampere and maximum-torque-per-voltage strategies. Moreover, the impact of each magnet arrangement is analyzed in connection with the energy consumption along four driving cycles, as well as the longitudinal acceleration and gradeability performance of the considered vehicle. The simulation results identify the most promising rotor solutions, and show that: (i) the appropriate selection of the rotor configuration is especially important for the driving cycles with substantial high-speed sections; (ii) the magnet arrangement has a major impact on the maximum motor torque below the base speed, and thus on the longitudinal acceleration and gradeability performance; and (iii) the configurations that excel in energy efficiency are among the worst in terms of drivability, and vice versa, i.e., at the vehicle level, the rotor arrangement selection is a trade-off between energy efficiency and longitudinal vehicle dynamics.

Evaluation of Accelerometer-Derived Data in the Context of Cycling Cadence and Saddle Height Changes in Triathlon

In the multisport of triathlon cycling is the longest of the three sequential disciplines. Triathlon bicycles differ from road bicycles with steeper seat tube angles with a change to saddle height altering the seat tube angle. This study evaluated the effectiveness of a tri axial accelerometer to determine acceleration magnitudes of the trunk in outdoor cycling in two saddle positions. Interpretation of data was evaluated based on cadence changes whilst triathletes cycled in an aerodynamic position in two saddle positions. The evaluation of accelerometer derived data within a characteristic overground setting suggests a significant reduction in mediolateral acceleration of the trunk, yielding a 25.1% decrease when saddle height was altered alongside reduced rate of perceived exertion (3.9%). Minimal differences were observed in anteroposterior and longitudinal acceleration. Evaluation of sensor data revealed a polynomial expression of the subtle changes between both saddle positions. This study shows that a triaxial accelerometer has capability to continuously measure acceleration magnitude of trunk movements during an in-the-field, varied cadence cycle protocol. Accessible and practical sensor technology could be relevant for postural considerations when exploring saddle position in dynamic settings.

Detection of Aircraft Touchdown Using Longitudinal Acceleration and Continuous Wavelet Transformation

The paper presents a methodology enabling the detection of aircraft touchdowns based on data obtained from accelerometers attached to the structural parts of the airframe in the cockpit or passenger compartment. Precise determination of the moment and place of touchdown of the main landing gear is challenging when analysing parameters such as height, flight speed and rate of descent. During the tests of the I-31T aircraft, it turned out that vibrations of the aircraft structure caused by the contact of the front and main landing gear with the ground have a repetitive character. In particular, this applies to longitudinal acceleration. The use of continuous wavelet analysis (CWT) allowed finding unique periodic features of the landing phenomenon that distinguish it from other forms of vibration occurring in individual flight phases. Ground and flight observations of experimental aeroplane MP-02 Czajka verified the proposed method of virtual touchdown detection. The results presented in this paper justify that this method may find broader application, especially for the light aircraft class.