Investigation of the Effect of Modifying the AlSi7Mg0.3 Alloy with a Fast-Cooled Master Alloy Using Heat Treatment

The development of modern high-tech industries of industrial production is impossible without the development of new methods for processing materials with high mechanical characteristics. There is a growing need for an increase in the proportion of parts made of aluminum alloys, a more complex configuration of cast parts, an increase in their reliability and durability in operation, etc. All this poses for metallurgists and foundry workers the task of creating new technologies for producing alloys, improving the technical and economic characteristics of structural materials, improving the quality and reducing the cost of castings.Hypoeutectic silumins have good casting properties, good weldability, machinability and corrosion resistance. However, they are prone to the formation of a coarse needle-like state, which reduces their useful characteristics. To eliminate this phenomenon, it is necessary to apply special technologies and the most common is their modification, which provides grain refinement. This makes it possible to use silumins for the manufacture of castings of complex shapes with increased density and low shrinkage porosity. Such parts can withstand average loads in critical units. Aluminum-silicon alloy AK7 or (ASi7Mg0.3) is a typical silumin, which is in demand in the automotive industry, construction, aircraft construction, machine, automobile and tractor production. It is appreciated for its good casting properties, weldability, machinability and corrosion resistance.

Trajectory Plotting Algorithm for a Self-Driving Road Grader

The deployment of self-driving technologies occurs in various industries and economic sectors. Self-driving taxi cabs can be found in city streets, in Russia as well as in other countries. The introduction of self-driving technologies in construction, namely, construction machinery, is a promising area that will develop rapidly in the nearest few years. A road grader is the construction machine whose control algorithms resemble those of selfdriving cars the most. One of the first development stages for the self-driving road grader is trajectory plotting. This article presents the developed trajectory plotting algorithm for the road grader taking into account its design features (minimum turn radius).

Mathematical models of wheel turning processes road construction vehicles

The construction of highways is a complex, multi-stage process. Most of the construction works are carried out according to the projects of structures and quite high requirements are imposed on the quality of execution. The fulfillment of these requirements is associated with great difficulties in view of the limited accuracy of the road construction machine itself, the lack of on-board control systems and the limited capabilities of the human operator, who is unable to determine the required exact parameters of the structure being built «by eye». To meet the requirements, three-dimensional control systems are used, which allow determining 3 coordinates of the working order of the machine – the vertical coordinate and the location of the machine on the construction site. At the same time, the digital project of the constructed structure should be the setter in such a system. The system determines the current position and compares it with the project. On the basis of this information, a control effect on the operating organ of the machine is formed. The course of movement and the speed of the machine when using such systems are determined by the machine operator. Further development of these systems should be four-dimensional systems – in which all control actions are assigned to the control system, starting from calculating the trajectory of the machine, choosing the speed, determining the required number of passes and ending with controlling the position of the working body of the machine at each moment of time. For the functioning of these systems, adequate mathematical models of the turning processes of road construction machines with different steering options are necessary.

Improvement of sound atmosphere in the compartment of construc-tion machine

Noise inside the compartment of construction machine makes the operator feel annoyed and exhausted due to the unwanted component of noise. This paper deals with the treatment of sound inside the compartment of construction machine to make the sound atmosphere desirable for the operator. The main cause of annoyance due to the exposure of noise is the peaky engine order components. This paper provides the method to reduce annoyance for the operator inside by the reduction of peaky components.

Psychological Effects of Heart Rate and Physical Vibration on the Operation of Construction Machine: An Experimental Study (Preprint)

BACKGROUND A construction method has emerged in which a camera is installed around a construction machine, and the operator remotely controls the machine while synchronizing the vibration of the machine with the images seen from the operator's seat using virtual reality (VR) technology. Indices related to changes in heart rate and physical vibration, such as heart rate variability (HRV) and multiscale entropy (MSE), can then be measured in the operators. As these indices are quantitative measures of autonomic regulation in the cardiovascular system, they can provide a useful means of assessing operational stress. OBJECTIVE This study aimed to improve the efficiency of machine operation by evaluating the changes in the heart rate and body vibration of the machine operators, while considering the psychological load on the operators. METHODS Nine remote operators (18–48 years old) participated in the experiment, which involved 42 measurements. A construction machine was driven on a test course simulating a construction site, and three patterns of operation—riding operation of the machine, remote operation using monitor images, and VR operation combining monitor images and machine vibration—were compared. The heartbeat, body vibration, and driving time of the participants were measured using a sensing wear made of woven film-like conductive material and a 3-axis acceleration measurement device (WHS-2). We used HRV analysis in the time and frequency domains, MSE analysis as a measure of the complexity of heart rate changes, and the ISO 2631 vibration index. Multiple regression analysis was used to model the relationship between HRV low frequency (LF)/high frequency (HF), MSE, vibration index, and driving time of construction equipment. Efficient driving time was investigated with a focus on stress reduction. RESULTS Multiple comparisons using the Bonferroni test and Kruskal-Wallis test showed statistically significant differences (P=.05) in HRV-LF/HF, the vibration indices Aw and motion sickness dose value (MSDV), and driving time among the three operation patterns. The riding operation was found to reduce the driving time of the machine, but the operation stress was the highest in this case; operation by the monitor image was found to have the lowest operation stress but the longest operation time. Multiple regression analysis showed that the explanatory variables (LH/HF), R-R interval (RRI), and vibration index (MSDVz by vertical oscillation of 0.5–5 Hz) had a negative effect on driving time (adjusted R2=0.449). CONCLUSIONS A new method was developed to calculate the appropriate operating time by considering operational stress and suppressing the physical vibration within an acceptable range. By focusing on the relationship between psychological load and physical vibration, which has left unexplored in previous studies, the relationship of these variables with the driving time of construction machines was clarified.

Perception of Vestibular Sensation During Turning Operation of Construction Machine

A major challenge in remote control is the reduction in work efficiency compared with on-board operation. The factors of reduction in work efficiency include a lack of information (information such as perspective, realistic sensation, vibration, and sound) compared to on-board operations. One of the factors is the lack of vestibular/somatosensory information regarding rotation. To clarify the effect of the presence of input of vestibular/somatosensory information regarding rotation on the worker’s operation, we conducted a basic laboratory experiment of a horizontal turning operation. The experimental results indicate that a response appropriate for the input of information regarding rotation can be made only with visual information; however, the reaction is delayed in the case without the input of information regarding rotation in comparison with a case with the input of information regarding rotation.

Improved Tilt Feeling During Remote Control of Construction Machine by Tactile Sensation

The aim of this work is to develop a technology that allows a remote operator of construction machine to feel the situations in a real working site to prevent fall accidents. In tele-operated maneuvering construction machine, it is difficult to recognize the tilt of the vehicle using only images from a camera mounted on the remote vehicle. Therefore, this study focuses on transmitting the feeling of the tilt using a controller with tactile stimulation. A gamepad-type tactile controller that performs palm pressurization is utilized to provide the tactile stimulus. The vehicle’s tilt is expressed by the palm pressure, which changes in corresponding to the vehicle’s pitch and roll angle. This study involves an experiment in which 10 subjects operate a vehicle remotely to climb on a slope. The subjects reported the tilt of the slope felt during the operation. The reported tilt is compared with those obtained by camera images only. The experiment results show that the accuracy of the recognized tilt was improved by 31.7% by utilizing a tactile stimulus when compared with the case involving operation using vision only. A subjective evaluation is performed using a five-point scale questionnaire. The results confirmed that the feeling of tilt, which is difficult to transmit using only video, was improved by 34%. This is an effective technology that transmits the feelings experienced in the remote field in real time. The proposed technology is thus expected to be useful for further development of teleworking technologies.