Swing Angle Research Articles

Evaluation of Effect of the Excavator Cycle Duration on its Productivity

Hydraulic excavators currently used at open pit mines, in particular backhoes, are more maneuverable, mobile and have more digging capabilities than rope shovels. This makes them suitable for a variety of conditions: top and bottom digging, loading lower, higher and at the standing level. The variants of mutual arrangement of the excavator and the dump truck, respectively, affect the duration of the excavator cycle, which, in turn, directly affects the productivity of the excavator. This article evaluates changes in the productivity of an excavator, depending on its angle of rotation and options for digging and loading. It is determined that the smaller the swing angle of an excavator, the greater its impact on productivity. Based on the executed calculations relative decrease in productivity (in percent from the most optimum variant) is established. Results of work can be used at planning of open pit mining for the purpose of definition, for example, speed of mining front movement at change of parameters of an excavator face and a type of a digging and loading.

Fuzzy controller for the treadmill speed adaptation system in mechatronic device for gait reeducation

Training with use of mechatronic devices is an innovative rehabilitation method for patients with various locomotor dysfunction. High efficiency of training is noted in systems that combine a treadmill or orthosis with a body weight support system. Speed control is a limitation of such rehabilitation systems. In commercially available devices, the treadmill speed is constant or set by the therapist. Even better training results should be obtained for devices in which the speed of the treadmill will be automatically adjusted to the patient walking pace. This study presents a mechatronic device for locomotor training that uses an algorithm to adjust the speed of the treadmill. This speed is controlled with use of a sensor that measures the rope inclination. The end of rope is fastened to the orthopaedic harness. Speed control is realized in such a way that ensures the smallest possible swing angle of the rope. A fuzzy controller was applied to adjust the treadmill speed. The drive system of the treadmill is equipped in a servodrive with PMSM motor and energy recovery module, which allows smooth speed control, limiting acceleration and minimizing electricity consumption. The presented solution was implemented in a real object and subjected to experimental tests.

Quality prediction of plunger components based on the finite element method during the neck-spinning process

To improve the neck-spinning processing quality of plunger components, a reliable finite element (FE) model was established and validated by the experimental spinning force. In the advanced FE model, an additional analysis step was added to obtain the pulling-out force, the axial clearance, and the swing angle of the plunger components after the neck-spinning process. Thus, the neck-spinning quality of the plunger components can be predicted. The results show that the simulated results using the FE model agree with the experimental results very well. The radial and axial spinning forces are approximate 3 and 2 times of the tangential spinning force, respectively. Finally, the influences of spinning parameters (e.g., feed rate and rotating speed) on the finished pulling-out force, axial clearance, and swing angle were evaluated in detail. The pulling-out force increases with increased feed rate, which tends to be stable with increased rotating speed. Compared with the stable tendency of axial clearance affected by feed rates, the axial clearance decreases significantly with increased rotating speeds. The swing angle of plunger components remains stable with different feed rate and rotating speed after the neck-spinning process.

Adaptive Sliding-Mode Control of an Offshore Container Crane With Unknown Disturbances

In this paper, an adaptive sliding-mode control (ASMC) for offshore container cranes that load/unload containers from a mega container ship to a smaller vessel is investigated. To withstand the harsh working conditions in the open sea, such as ship motions and winds, a 4-degrees-of-freedom control model consisting of plant uncertainties and known/unknown disturbances is newly developed. After decoupling the actuated (i.e., trolley displacements) and unactuated (i.e., swing angles) joint variables, a sliding surface that incorporates the decoupled dynamics is designed. Then, a new sliding-mode control (SMC) algorithm with two adaptation laws for switching- and equivalent-control inputs is developed. The asymptotic stability to the “real” sliding surface introduced in the decoupled (actuated, unactuated) state space is proven without a priori knowledge on the bounds of unknown disturbances. For the experiment, a three-dimensional crane mounted on a Steward platform to generate the ship motions is utilized. To verify the effectiveness of the proposed ASMC method, experimental results of the proposed method are compared with two representative works: the SMC presented by Ngo and Hong and the ASMC presented by Zhu and Khayati. The vibration suppression capability of the proposed method in the presence of ship motions, large initial swings, parameter uncertainties, and sudden disturbances is superior to the two compared methods. The developed algorithm can be used for a mobile harbor system as a new tool in the modern maritime industry.

Evaluation for the Synchronization of the Parade with OpenPose

In military organization, the synchronization in the parade is important for showing their majesty. However, we do not have any quantitative evaluation methods for the parade. In this research, as a first step of the quantitative evaluation for the parade, we propose an evaluation method focusing on the synchronization level of “Marking Time”, in which soldiers is moving their legs as in marching without step forward, between two persons with OpenPose. In order to measure the synchronization level, our method is based on the trend of the transition of arm swing angles in the parade, and the result shows our method is appreciable for measuring the synchronization level for two persons.

PEDOT coating enhanced electromechanical performances and prolonged stable working time of IPMC actuator

Current ionic exchange polymer metal composite (IPMC) has always been associated with short stable working time due to the presence of severely electrode fatigue and water loss, which limits its wide-spread applications. To address this problem, a facile and effective strategy has been proposed to repair the IPMC by electrografting a conductive, flexible polymer of Poly(ethylenedioxythiophene) (PEDOT) on IPMC electrode surface in this study. The investigation of physiochemical properties of PEDOT coating revealed that EDOT molecules could fill into the electrode cracks generated from fatigue and then were polymerized into PEDOT with a linear conjugation structure. The PEDOT-coated electrodes exhibited significantly improved conductivity and effectively reduced water loss. The PEDOT coating can repair the common actuation defects of the used IPMC actuators, such as asymmetrical actuation and torsional deformations. Moreover, the introduction of PEDOT coating apparently improved electromechanical properties by increasing swing angles and displacements, and prolonging the stable working time to more than 1000sec without fatigue.

Research on Improved Pedestrian Dead Reckoning Algorithms

In view of user's requirements of high performance, easy operation and low cost with indoor location, data acquisition software based on Android platform utilize sensors built-in cellphone is used to study the pedestrian dead reckoning (PDR). Step detection and step length estimation are carried out by collecting leg swing angle while walking, and the classical step length estimation algorithm is improved. At the same time, the improved heuristic drift elimination algorithm is used to calculate the direction. Finally, the experiment results show that the PDR technology can better satisfy the requirements of indoor pedestrian positioning, and as for the low-cost multi-sensor. compared with the existing algorithm, the improved algorithm with higher positional accuracy.

Research on Grab Swing Control Method Based on Time Delay Filter

Grab swing during crane acceleration and deceleration will have an impact on work efficiency and safety. In this regard, the swing amplitude of the grab during the operation must be controlled within a certain range. According to the mechanical analysis of bridge crane’s grab, the mathematical model between crane’s horizontal movement and grab swing is established. A time delay filter technique is applied to shape the acceleration control signal, thus effectively control the swing angle of the grab. Simulation results show that the control method with time delay filter could eliminate the swing of the grab even without measuring the swing angle, and is feasible for engineering applications.

The real-time vision measurement of multi-information of the bridge crane’s workspace and its application

The measurement of the workspace information of the bridge crane is the premise of its intelligent control and safety monitoring. Some existing vision systems can only obtain very limited information, like swing angle of the payload. In this paper, a monocular vision measurement method is proposed to acquire multi-information of the payload off-centered angle, the payload rotation angle and the obstacle height. A hierarchical calibration method is designed to divide the large lifting height of the crane into multi-layers. At each layer, four markers are fixed on a plate symmetrically to obtain the center position of hook via the Blob analysis and ellipse fitting algorithm. After calibration, two fitting equations of the payload lifting height and the pixel coordinate of vertical lifting center are established corresponding to the pixel distance between two markers and the height of each layer. On the base of the two fitting equations, the measurement models of the payload off-centered angle, the payload rotation angle and the obstacle height are established combining with the geometric relations in the crane’s workspace, respectively. Finally, a crane prototype is established to validate the effectiveness of the vision measurement models. Moreover, the strategies of auto-centering control and automatic obstacle avoidance are designed utilizing the vision measurement system. The corresponding experiments were carried out and achieved a good performance. The research results of this paper have practical significance to intelligent control and safety monitoring of the crane in future.

Process path planning based on efficiency model for ultrasonic cutting curved surface of honeycomb composite parts

According to the roughing chip shape, the ultrasonic vibration cutting honeycomb material curved surface parts are divided into two rough machining processes of “V” shape cutting and rectangular cutting. Based on the non-interference characteristic cutter location counting model, the cutting efficiency model is established to select a better process. First, the residual height model of the two processes is established, and the residual height is controlled by longitudinal and lateral lifting the cutter location. Second, using the coordinate system conversion principle, the projection method is used to perform global interference check on the triangular-blade and the disk-blade which are used for ultrasonic cutting honeycomb composite, and then the characteristic cutter location generation method for changing the swing angle to avoid interference is proposed. Finally, a cutting efficiency model is established. Process analysis of case parts shows: when the feed rate of disk-blade is less 0.6 times to that of triangular-blade, the machining efficiency of “V” shape cutting is higher than that of rectangular cutting. When the disk-blade’s feed rate approaches or exceeds the triangular-blade’s, especially under this circumstance that the large parts is cut, the efficiency of the latter is higher.

Study on the particle stratification and penetration of a swing vibrating screen by using DEM

PurposeAs for vibrating screen, the separation of granular materials is a very complicated process, particularly the screening with a swing trace. To study the characteristics of stratification and penetration in the swing vibrating screen, a three-dimensional numerical model was developed to simulate the screening process.Design/methodology/approachThe discrete element method (DEM) was used to perform the numerical simulation, and the kinetic model of the swing screening was established. The regions of stratification and penetration were defined, and the mathematical functions relating fine particle ratio of stratification and penetration to time were presented using the least squares method.FindingsThe results show that the low value of frequency (5 and 10 Hz) has a limited effect on the stratification, while the obvious effect can be found at high frequency. A low frequencies or small swing angles may enhance the particle penetration. By studying the vibration parameters affecting the stratification and penetration rate, it is found that the frequency has more influence than the swing angle.Originality/valueThe higher screening efficiency and processing capacity can be further obtained for the swing vibrating screen by comparing with the linear vibrating screen. These results reveal the fundamental characteristics of particle motion in the swing screening, which will provide reliable guidance for studying the design optimization of vibrating screen.

A family of anti-swing motion controllers for 2D-cranes with load hoisting/lowering

Abstract This paper presents a methodology for designing controllers that attenuate the payload swing angle in two-dimensional overhead crane systems with varying rope length. The proposed scheme is based on the proper construction of a design function, which combines the coordinate of the translational motion of the crane with that corresponding to the swing angle. The proposed methodology shows how to design a family of functions that can be used not only to attenuate the swing angle but also to follow a desired motion. Then, the controller is implemented in combination with a trajectory design stage based on S-curves. The proposed scheme is compared with a controller with a proportional derivative structure and an adaptive controller. Numerical and experimental results validate the proposed methodology and show the effectiveness of the proposed controller even when the system is being affected by state estimation errors and external disturbances.

Passivity-based Nonlinear Control for a Ballbot to Balance and Transfer

Ballbot is a robot that can transfer to a given position while maintaining a self-balanced upright posture on a spherical ball. This paper proposes a nonlinear control of a ballbot using three omnidirectional wheels in the driving mechanism. Assuming a small swing angle for balance, the full dynamics of the ballbot can be decomposed into three, which are two underactuated dynamics for two orthogonal vertical planes and the fully actuated dynamics for one horizontal plane. The passivity of closed-loop systems of vertical planes is derived from the modified potential energy function. The proposed controller is designed to control the balancing and transferring of the system based on Lyapunov theory and the passivity of the system. A proportional-derivative feedforward controller is applied to regulate the heading motion in the horizontal plane. Experiments are performed with a real ballbot system to validate the effectiveness of system modeling and to show the controllability of the proposed algorithm.

Multifunctional Sensor Based on Translational‐Rotary Triboelectric Nanogenerator

AbstractTriboelectric nanogenerators with a large number of desirable advantages, such as flexibility, light weight, and easy integration, are unique for sensor design. In this paper, based on the triboelectric nanogenerator (TENG), a cylindrical self‐powered multifunctional sensor (MS) with a translational‐rotary magnetic mechanism is proposed, which has the capacity to detect acceleration, force, and rotational parameters. The MS can transform a translational motion into a swing motion or a multicircle rotational motion of a low damping magnetic cylinder around a friction layer and hence drives the TENG to generate voltages output. For enhancing the output performance of the TENG, an electrode material with small work function, low resistance, and suitable surface topography is the best choice. According to the structure characteristic of the translational‐rotary magnetic mechanism, the MS can easily respond to a weak striking and can be used to measure the rotational parameters without the need of coaxial installation. Based on the MS, some applications are established, for example measuring the punch acceleration of a boxer, the hitting force and swing angle of golf club, which demonstrate the feasibility and efficiency of the MS and exhibit that the MS could find applications in sports.

Nonlinear control of unmanned aerial vehicles with cable suspended payloads

This paper focuses on the mathematical modeling and control of an unmanned aerial system (UAS) with a payload suspended using a cable. The motion of the payload induces disturbances on the aerial platform and needs to be mitigated for stable operation. The solution to this control problem is presented through the implementation of a passivity based controller, and an extended state observer based active disturbance rejection controller. The implementation of the passivity based controller requires the knowledge of higher time derivatives of the payload oscillations. Assuming only the swing angles of the payload with respect to a UAS are measured, these states (primarily the angular velocity) are estimated using a continuous-discrete Kalman Filter. Alternately since, the payload cable swing angle is difficult to measure, an active disturbance rejection controller is designed and implemented wherein the disturbance induced in the system due to the motion of the payload is estimated using the extended state observer. A comparison between the passivity based controller and the extended state observer based active disturbance rejection controller is performed using a high fidelity numerical simulation.

Experimental analysis and parameter optimization of pdc bit for rock drilling trolley

The design parameters of PDC bits for rock drilling trolley have not been studied in depth and it is lack of theoretical research basis. So the service life of the bits for tunnel tunneling construction cannot meet the design and application requirements. Taking three-arm rock drilling trolley as the experimental platform, the key parameters of PDC bit crown profile shape, caster angle, cutting tooth size, tooth arrangement density, inner cone angle, outer swing angle and crown top shape for rock drilling trolley are designed by combining the optimum design method, empirical numerical value and experimental correction. The key parameters were optimized and improved through a set of manufactured bits, and a set of drills were manufactured again for the following experiment. The experimental data in second stage shows that the broken and drop defects of the improved bits are greatly reduced. The drilling depth is significantly increased, and the service life is also improved, which meets the requirements of design and operation.

Transportation Control of Double-Pendulum Cranes With a Nonlinear Quasi-PID Scheme: Design and Experiments

In real-world applications, industrial cranes commonly suffer from effects caused by the so-called double-pendulum phenomenon in many situations. However, at present, the double-pendulum phenomenon is usually directly roughly neglected when designing control methods. For double-pendulum cranes, most currently available approaches are open loop control; the existing feedback methods are mostly developed based on linearized dynamic models (around the equilibrium point) or designed without adding integral terms in the control laws, which may cause positioning errors in the presence of unmodeled dynamics. To address these problems, this paper proposes a new quasi-proportional integral derivative control method to effectively control underactuated double-pendulum crane systems. Then, we provide rigorous theoretical analysis for the equilibrium point of the closed-loop system based on the original nonlinear dynamic equations. To our knowledge, this paper gives the first plant-parameter-free controller that incorporates both integral action and actuating constraints without any linearizing operations during controller design or closed-loop analysis, which theoretically ensures that the controller can work well in the presence of unmodeled dynamics (e.g., insufficient friction compensation), actuating constraints, and large swing angles (i.e., not satisfying linearization conditions). Finally, hardware experimental results are provided to examine the effectiveness of the suggested control method.

Antiswing Cargo Transportation of Underactuated Tower Crane Systems by a Nonlinear Controller Embedded With an Integral Term

A tower crane is a nonlinear mechatronic system with complicated underactuated characteristics, which is widely used in modern construction sites. At present, most existing methods for tower cranes are proposed by linearizing the original nonlinear dynamics near equilibrium points, which are, thus, prone to suffering from unexpected steady errors due to such factors as unmodeled dynamics, imperfect friction compensation, etc., since they have not included integral terms in either controller design or stability analysis. Therefore, in this paper, an improved feedback controller with an elaborately constructed integral term is proposed for 3-D tower cranes without linearization, which can achieve both antiswing and positioning control while being able to effectively reduce steady errors in the presence of, e.g., inaccurate friction compensation. Furthermore, asymptotic stability results are proven through rigorous theoretical analysis. Owing to no linearization, the proposed controller is applicable when state variables (e.g., cargo swing angles) are not close enough to the equilibrium points, which makes it suitable for complicated working conditions. Hardware experimental results are included to verify the effectiveness of the proposed controller. Note to Practitioners —This paper is motivated by the requirement of effective control methods for tower cranes. Tower cranes are widely applied in modern construction sites to fulfill cargo transportation tasks. For such systems, the jib slew motion not only enlarges the workspace but also brings more difficulties to suppress unexpected cargo swing during the transportation process. Up until now, most existing methods use simplified system models or need exact model knowledge, which are difficult to reflect real dynamics in many practical situations. To handle these existing problems, in this paper, a novel feedback control approach embedded with an elaborately constructed integral term is presented without model linearization. By introducing the integral term, even when frictions are inaccurately compensated, steady errors can be reduced effectively and, hence, the positioning accuracy can be improved. Also, the proposed controller can handle parametric uncertainties. By applying the proposed controller, the closed-loop system achieves asymptotic results, which is rigorously proven theoretically. Finally, the effectiveness of the proposed controller is verified by implementing several groups of hardware experiments. In the future studies, we will apply the proposed method in practical applications.

Mathematical and experimental analysis of the thermal effectiveness of an oscillating jet with side-to-side swing louvers in a cassette split type air conditioner

The impact of air supply control strategies (louvers movement) on indoor thermal environment were evaluated in this study. The temperature uniformity was evaluated by: (i) the air distribution performance index (ADPI) to determine the air diffusion performance in heating mode; (ii) the air draught rate (DR%) on the face to determine the local discomfort due to cold draught; (iii) the mathematically determined vertical temperature stratification in a room with Beta distributions. A comparison of the conventional type with three different oscillating type airflows (louvers swing angle ±20°, ±40° and ±60°) were experimentally analysed to determine appropriate air supply control strategies. The results indicated that Beta distributions could capture the overall trend of the oscillating airflow, to establish the acceptable thermal uniformity and higher thermal effectiveness. The oscillating airflow as generated by the side-to-side swing type delivery louvers mounted inside a cassette split type air conditioner could shorten heating time by 20% to attain room temperature from 9°C. The data reveal that oscillating airflow can provide a better thermal sensation to feeling warm in the heating mode at both ankle and neck level. The ADPI is approximately 85% in the occupied zone. The actual draught rates on the face ranged 0–35%.

A novel motion platform system for testing prosthetic knees

The principle of a novel motion platform system (NMPS) for testing prosthetic knees (PKs) is proposed to imitate the stochastic dynamic processes. The NMPS is realized by commanding a thigh simulator to imitate thigh motions of a tester in real time. The NMPS includes a motion platform, a bio-guided unit, a posture sensing unit, and a control and data collection unit. An indirect approach to obtain the vertical motion of the tester’s hip joint is proposed and experimentally validated. The prototype of the NMPS is fabricated. The prototype’s ability to imitate the tester’s thigh motions is experimentally tested at an accelerated/decelerated walking speed. Correspondingly, the swing angle of the developed four-bar linkage prosthetic knee based on magnetorheological effect (FLPKME) is experimentally tested and analyzed. The experimental results indicate that the developed NMPS can accurately imitate the amplitudes and speeds changing in the stochastic dynamic processes of the healthy un-amputated individual’s thigh.