Boom Arm Research Articles

Electrohydraulic musculoskeletal robotic leg for agile, adaptive, yet energy-efficient locomotion

Robotic locomotion in unstructured terrain demands an agile, adaptive, and energy-efficient architecture. To traverse such terrains, legged robots use rigid electromagnetic motors and sensorized drivetrains to adapt to the environment actively. These systems struggle to compete with animals that excel through their agile and effortless motion in natural environments. We propose a bio-inspired musculoskeletal leg architecture driven by antagonistic pairs of electrohydraulic artificial muscles. Our leg is mounted on a boom arm and can adaptively hop on varying terrain in an energy-efficient yet agile manner. It can also detect obstacles through capacitive self-sensing. The leg performs powerful and agile gait motions beyond 5 Hz and high jumps up to 40 % of the leg height. Our leg’s tunable stiffness and inherent adaptability allow it to hop over grass, sand, gravel, pebbles, and large rocks using only open-loop force control. The electrohydraulic leg features a low cost of transport (0.73), and while squatting, it consumes only a fraction of the energy (1.2 %) compared to its conventional electromagnetic counterpart. Its agile, adaptive, and energy-efficient properties would open a roadmap toward a new class of musculoskeletal robots for versatile locomotion and operation in unstructured natural environments.

A low cost and simple webcam spectrometer for exploring the visible wavelengths of light

This paper presents a method for constructing a simple, cost-effective, and versatile spectrometer using readily available materials such as a basic webcam, a DVD, tin foil, a cardboard tube, and a microphone boom arm. Building upon previous designs (Widiatmoko et al 2011 Phys. Educ. 46 332, Lorenz 2014 Am. J. Phys. 82 169–73, Rodrigues et al 2016 Phys. Educ. 51 014002, Likith et al 2021 J. Opt. 50 489–94), this spectrometer is mounted on a microphone boom arm, enhancing flexibility in capturing spectra from various angles and distant light sources. The spectrometer, coupled with Theremino Spectrometer V3.1 software, achieves sufficient resolution to measure solar Fraunhofer lines and closely spaced Mercury double lines at 436 nm and 577 nm. The procedure for assembling the spectrometer is detailed, including calibration using a Mercury CFL lamp or phone screens. Results demonstrate the spectrometer’s capability to capture high-resolution spectra of the blue sky and light sources, identifying significant spectral lines. This DIY spectrometer offers an accessible tool for amateur scientists and educators to explore visible light spectra, facilitating both qualitative and quantitative analyses. Also, through measuring the light from phone screens work, perception of colour can be explored.

Mining Trajectory Planning of Unmanned Excavator Based on Machine Learning

Trajectory planning plays a crucial role in achieving unmanned excavator operations. The quality of trajectory planning results heavily relies on the level of rules extracted from objects such as scenes and optimization objectives, using traditional theoretical methods. To address this issue, this study focuses on professional operators and employs machine learning methods for job trajectory planning, thereby obtaining planned trajectories which exhibit excellent characteristics similar to those of professional operators. Under typical working conditions, data collection and analysis are conducted on the job trajectories of professional operators, with key points being extracted. Machine learning is then utilized to train models under different parameters in order to obtain the optimal model. To ensure sufficient samples for machine learning training, the bootstrap method is employed to adequately expand the sample size. Compared with the traditional spline curve method, the trajectories generated by machine learning models reduce the maximum speeds of excavator boom arm, dipper stick, bucket, and swing joint by 8.64 deg/s, 10.24 deg/s, 18.33 deg/s, and 1.6 deg/s, respectively; moreover, the error does not exceed 2.99 deg when compared with curves drawn by professional operators; and, finally, the trajectories generated by this model are continuously differentiable without position or velocity discontinuities, and their overall performance surpasses that of those generated by the traditional spline curve method. This paper proposes a trajectory generation method that combines excellent operators with machine learning and establishes a machine learning-based trajectory-planning model that eliminates the need for manually establishing complex rules. It is applicable to motion path planning in various working conditions of unmanned excavators.

A new system for measuring boom displacement in a field crop sprayer

This study proposes an innovative system for measuring the displacement of a sprayer boom’s tips and calculating their velocity and acceleration in the horizontal and the vertical plane. The system measures the length of measuring cables which are attached at the end of a sprayer boom’s tips. Two supports are mounted in the central part of the sprayer boom. Absolute rotary encoders with measuring reels and tension springs are attached to the supports, which enables the system to determine changes in the position of boom arms in two perpendicular directions. The signals generated by each encoder are transmitted to a computer by a rapid data acquisition device, and they are transposed to the indicated parameters. The designed system can be used to measure sprayer boom displacement both in the field and in laboratory experimental tracks.

Simulation Study on Energy Recovery and Regeneration of Hybrid Loader Arm

In response to the problem of large energy waste in the loader actuator, a hybrid loader boom arm energy recovery and regeneration system is proposed, which adopts a supercapacitor as the energy storage element. Firstly, the working principle of the hybrid loader boom arm energy recovery and regeneration system is analyzed. Secondly, the mathematical model of the components is analyzed. Finally, AMESim is used to model the system. The simulation is carried out under typical working conditions with the LiuGong ZL50C loader as the simulation object and compared with the conventional system. The simulation results show that the hybrid power system does not affect the motion characteristics of the loader boom arm system compared with the conventional system. The hybrid power system can perform energy recovery regardless of the mode of operation, and the energy recovery efficiency reaches 55.7 %. When the system enters the hybrid mode, the supercapacitor SOC fluctuates less, and the energy regeneration efficiency reaches 90 %. The hybrid power system can effectively reduce engine fuel consumption and pollutant emissions, with the system's energy-saving efficiency of 44.4 % and CO, HC, and NOx emissions reduced by 41.1 %, 47 %, and 19.8 %, respectively. The system provides a reference for the research of energy-saving technology of the loaders, effectively reducing the operating cost of the loaders.

Simulation Study on Variable Pressure Margin Energy Recovery of Electric Loader Actuator

The conventional electric loader uses a motor instead of an engine, which aligns with the current energy-saving and emission-reduction trend. However, the motor’s speed control performance and overload capacity are under-utilized, and the actuator suffers from the potential energy waste problem of the boom arm. This study proposes a variable pressure margin energy recovery system for the electric loader actuator. It uses a combination of a permanent magnet synchronous motor (PMSM) and a quantitative pump. It can achieve variable pressure margin control and energy recovery through the pressure feedback closed-loop control. AMESim is used to build the simulation model based on the system control strategy, actuator, supercapacitor, and PMSM mathematical mode. Under typical working conditions, the simulation study is conducted on a 50-type wheel loader to obtain cylinder displacement, system energy recovery, and energy-saving performance. The simulation results show that the system is feasible and can effectively reduce energy consumption. Its energy recovery efficiency is 65.4%. The PMSM energy supply is reduced by 28.6% with the variable pressure margin control. It has high energy-saving performance, and the energy-saving efficiency is 38.5%. It provides a reference for research on energy-saving systems for electric construction machinery.

Numerical Analysis of Energy Recovery of Hybrid Loader Actuators Based on Parameters Optimization

The conventional loader actuator hydraulic system suffers from the potential energy waste problem of the boom arm. This study proposes a hydraulic control method and control strategy for the energy recovery and regeneration of a hybrid loader arm. When the boom arm drops, the piston side of the boom cylinder charges the accumulator, and the system achieves energy recovery. When the boom arm rises, the accumulator releases hydraulic energy to drive the energy regeneration hydraulic motor to provide energy for the system, and the system achieves energy regeneration. The system’s principle analysis and the mathematical model are completed based on Boyle’s, Newton’s second law, and the flow continuity principle. The simulation model is established using AMESim 2D mechanical library, HCD library, and signal library. Under the typical working condition, 50-type wheel loader numerical simulation research is conducted, and the system cylinder motion characteristics, accumulator charging and discharging performance, system energy recovery, and regeneration performance are obtained. On this basis, energy recovery and regeneration efficiency are selected as optimization objectives. The optimal designs of accumulator and energy regeneration hydraulic motor parameters are carried out to obtain the influence law of accumulator and hydraulic motor parameters on system energy recovery and regeneration, and the energy-saving effect of the system is analyzed. The results show that the optimized parameters effectively improve the system energy recovery and regeneration efficiency and reduce engine fuel consumption. The system provides a reference for designing an energy recovery system and researching the energy-saving technology of loaders.

Vonnisbespreking: Waagartieste leer haar heiland ken. Gevestigde regsbeginsels egter tot haar redding Jackson v Road Accident Fund 2021 4 SA 244 (GP)

In Jackson the court had to decide whether the plaintiff, a stuntwoman by profession, had given consent to the risk of injury before she was seriously injured during the filming of an exciting scene in which she had to ride a motorcycle at high speed towards a vehicle carrying a camera approaching from the opposite direction. Due to the negligence of the driver of that vehicle the camera which had been dangling from a boom arm had been lifted too late to avoid a collision with the plaintiff. The gist of the defendant’s plea was that the plaintiff had known that she was engaged in a hazardous exercise, which implied that she had accepted the risk of harm that ultimately befell her. The court first dealt with the issue of negligence, which, according to some academic writers, should have been postponed until a decision on possible wrongfulness of the driver had been made. In view of recent decisions of the Supreme Court of Appeal it is shown that the court’s approach in finalising the issue of the driver’s negligence and the lack of contributory negligence on the plaintiff’s part was justified. The court approached the issue of consent to the risk of injury (voluntary assumption of risk) by reiterating the three basic requirements for establishing whether the plaintiff had consented to the risk of injury, namely full knowledge of the extent of the risk, appreciation of the ambit of the risk and subjective consent (authoritatively established in 1904 in Waring & Gillow Ltd v Sherborne). It then applied four previous judgments (and in addition referred to one more) to the facts (Durban City Council v SA Board Mills Ltd, Kepko v Road Accident Fund, Lampert v Hefer and Santam Insurance Co Ltd v Vorster; reference to Oosthuizen v London and Lancashire Insurance Co Ltd) and effectively reached the conclusion that the issue of consent in such circumstances is fact-sensitive in that a court has to guard against drawing conclusions from circumstances such as are present in the case under discussion, for example that the plaintiff had been occupied in exercising an intrinsically dangerous profession. Each of these judgments is briefly discussed to demonstrate how they were applied by the court to found its final conclusion. This judgment again demonstrates that courts are bound to determine the exact state of mind of the plaintiff to be able to ascertain whether he or she had in fact realised and appreciated the risk which he or she has accepted and had subjectively consented to it. The onus of proof on a defendant employing this defence is daunting and the value of good cross-examination of a plaintiff in cases of this nature is emphasised. This judgment provides a good example that can be utilised by lecturers for explaining the operation of the ground of justification of volenti non fit iniuria (literally: “To a willing person, it is not a wrong”) in the guise of voluntary assumption of risk to students. Finally, there is a reference to the relevance of English case law for resolving issues pertaining to consent cases of the risk kind in South Africa. It is noteworthy that a leading English authority, the 1891 Appeal Court case of Smith v Charles Baker & Sons which was quoted as good authority as far back as 1904 in Waring & Gillow Ltd v Sherborne is still regarded as applicable in modern English tort law in respect of actions instituted by employees who suffered harm in the scope of their employment while undertaking risky operations.

Cooperative Docking Guidance and Control with Application to Civil Autonomous Aerial Refueling

This paper proposes a novel concept for automatic docking of a boom-receptacle aerial refueling system adequate for civil aerial transportation. The receiving aircraft is assumed to keep straight and steady flight, and the docking maneuver is performed exclusively by the tanker and its boom system. As opposed to the conventional approach, the docking maneuver consists in a coordinated and guided motion of the tanker and the boom arm that is simultaneous with the extension of the nozzle tip. To achieve this, a cooperative guidance algorithm is derived in a systematic manner. The first step is to reduce the docking problem to a planar kinematic guidance problem. Subsequently, the cooperative guidance law algorithm is derived and applied to generate commands for the inner-loop controllers of the tanker aircraft and the boom. The ability to achieve successful docking is demonstrated using numerical simulations, and advantages of this concept are highlighted using a comparison with a baseline controller that uses separated control of the tanker and the boom in a sequential manner.

Coordination of construction manipulation robotic system using UAV

Drone technology has demonstrated to be of great contribution to the construction field. Tasks such as photogrammetry, plot surveillance and assets inspections are successfully automated with the aerial robotic technology with some level of contribution of a human operator. In this paper we analyse the possibility to achieve fully automated construction task using dispersed robotic system: a drone and mobile robotic crane. The role of the drone is to study the surroundings and generate a desired trajectory for the crane boom arm in order to lay-in pergola blades. The paper focuses on the layers of the dispersed cyber-physical system allowing to achieve such complex task and optimize the trajectory of the crane boom arm by resolving two-dimensional Chebyshev-Gauss collocation method in order to have minimum-jerk path.

Optical coherence tomography (OCT) in unconscious and systemically unwell patients using a mobile OCT device: a pilot study

ObjectiveThis study aims to evaluate the feasibility of retinal imaging in critical care using a novel mobile optical coherence tomography (OCT) device. The Heidelberg SPECTRALIS FLEX module (Heidelberg Engineering, Heidelberg,...

Design and analysis of demolition robot arm based on finite element method

As a novel robot which mainly engages in the demolition and transformation of various concrete buildings, the demolition robot has developed rapidly in recent years. The impact force is mainly produced by the breaking hammer installed in the front end of the arm. As the most important part of a demolition robot, the boom arm is mainly composed of four parts including a supporting arm, a main arm, a fore arm, and a breaking hammer system. In this article, a mechanical model of the boom arm is established, and the finite element analysis obtaining the first four-order natural frequencies and modes is carried out in ANSYS Workbench. The results reveal that the resonation can be easily stimulated when a hydraulic breaking hammer is at the second-order frequency. The mounting block of the hydraulic breaking hammer, the hinge parts of the supporting arm, and the main arm are easily deformed or damaged in the Y direction by analyzing the deformation in three directions of the second-order mode. After the structure optimization, the vibration characteristics of the two parts are significantly enhanced, which provides a theoretical basis for optimizing the prototype and gives a reference in the experimental modes.

Management The Safety of Exploitation of the Rotation Mechanism in a Self-Propelled Crane

Abstract The article analyzes of the load capacity of the rotation mechanism of the boom arm sub-assembly for a self-propelled crane. The uneven flexibility of systems supporting structures of the machine was taken into account in the identification of the load. The consideration are illustrated by the example slewing bearing from self-propelled crane. FEM method was used for calculations. The basic problems of construction of numerical model were discussed. Sample calculations of bearing carrying capacity has been done taking into account flexibility of bearings supporting structures, which also allowed to define the internal load distribution in the bearing. On example of the supporting structure of the mobile crane DST 5050 the internal load distribution in the crane bearing at different positions of the crane machine body were defined. During the rotation of the crane body priority angels were indicated. It has been shown that the deformations of the supporting frames are so large that they significantly change the distribution of forces transmitted by the individual bearing rollers.

Kinematic Analysis of Hydraulic Excavator Working Device Based on D-H Method

To accurately describe the problem of excavator bucket teeth space trajectory in the mining process, is presented to describe the trajectory of excavator bucket teeth using D-H homogeneous coordinate method. Based on the principle of robotics, the excavator boom arm and bucket as three robot manipulators, through the driving of the boom cylinder and the arm cylinder and bucket cylinder, establish mathematical model of excavator working device pose space, using MATLAB/Simulink simulation to analyze the spatial motion, and fast get excavator mining envelope graph. The ZE-360 hydraulic excavator as an example, verify the scientific D-H homogeneous coordinate method in spatial motion analysis of excavator working device and adaptability, and provide a theoretical basis for the excavator trajectory and work space analysis.

Structural Analysis of Field Sprayer Booms

In this paper, structural analysis of a 21 meters wide field sprayer boom, designed for precision agriculture applications, was conducted with finite element analysis. G-programming language, a data acquisition board and an inductive force transducer were used to measure the forces acting on the boom arms. An experimental setup, developed in a laboratory environment, was able to measure and record various forces in 5 miliseconds intervals. An ANSYS model was developed to analyze the forces recorded during laboratory experiments. Steel (SAE/AISI St 42) and aluminum (ISO AlMg2.5) materials for the sprayer boom structure were used in the analyses. Based on the analysis results, using aluminum for active boom suspension system for field sprayers produced more favorable structural results than steel.

Aqueous Angiography in Living Nonhuman Primates Shows Segmental, Pulsatile, and Dynamic Angiographic Aqueous Humor Outflow

To evaluate the feasibility of safely performing aqueous angiography in intact eyes of living nonhuman primates (NHPs) for evaluating aqueous humor outflow and segmental patterns. Cross-sectional, observational study. Six nonhuman primates. Aqueous angiography was performed in 6 nonhuman primates. After anesthesia, an anterior chamber (AC) maintainer was placed through a temporal 1-mm side-port wound. Indocyanine green (ICG; 0.4%) or 2.5% fluorescein was introduced (individually or in sequence) into the eye with a gravity-driven constant-pressure system. Aqueous angiography images were obtained with a Spectralis HRA+OCT (Heidelberg Engineering GmbH, Heidelberg, Germany) suspended over the NHP eye using a custom-designed surgical boom arm. Concurrent anterior segment optical coherence tomography (OCT) was performed on distally angiographically positive and negative regions. Angiographic patterns described by location, time-course, choice of tracer, and anterior-segment OCT. Aqueous angiography in the living NHP eye demonstrated mostly stable angiographic patterns. With multimodal imaging, angiographically positive signal co-localized with episcleral veins as identified by infrared imaging and intrascleral lumens, as demonstrated by anterior segment OCT. Sequential aqueous angiography in individual eyes with ICG followed by fluorescein showed similar angiographic patterns. A pulsatile nature of aqueous angiographic outflow was sometimes observed. Aqueous angiographic patterns could also dynamically change. In some instances, positive angiographic flow suddenly arose in regions previously without an angiographic signal. Alternatively, an angiographic signal could suddenly disappear from regions in which an angiographic signal was initially documented. Aqueous angiography in living NHPs demonstrated segmental and pulsatile patterns with a newly described ability to dynamically shift. These characteristics further the understanding of live aqueous humor outflow biology and may be useful in improving glaucoma surgeries aimed at trabecular meshwork bypass.

A method to evaluate nonideal effects of anechoic chambers on multiple-angle measurements

Anechoic chambers are typically qualified by comparing sound pressures at several radial distances from a sound source and verifying that they follow the spherical spreading law within specified tolerances. While this technique is useful, it may not sufficiently characterize free-field variations at fixed radial distances and numerous angular positions, as are commonly used for directivity, sound power, and other important acoustical measurements. This paper discusses a technique to detect angular field deviations in anechoic chambers. It incorporates a loudspeaker in an altazimuth mount, an adjustable-radius boom arm, and a precision microphone. The boom arm and microphone remain in line with the loudspeaker driver axis at a fixed radius while the system rotates to specified polar or azimuthal angle increments. In an ideal free-field environment, the frequency response function from the loudspeaker input to the microphone output should remain consistent—regardless of the system orientation. However, in t...

Математическая модель функционирования энергосберегающего гидропривода механизма поворота лесного манипулятора

Presented simulation mathematical model of the mechanism of rotation of the column manipulator with energy-saving hydraulic drive. The model takes into account three mechanical process: the rotational movement of the column arm around a vertical axis load sway relative attachment points on the boom arm and the piston motion of fluid accumulator. To describe the rotation of the column using the basic equation of dynamics of rotational motion. The load represented either as a mass point, when the dimen-sions are small and the proportionality, or a rod if the simulated moving manipulator logs or pipes.

THE MATHEMATICAL MODEL OF HYDRAULIC SYSTEM OF BOOM MANIPULATOR

Hydraulic forest machines and their components - complex dynamic systems operating under conditions of changing external influences due to the many and varied factors. These factors include: the parameters of the trees that are the subject of labor, weather conditions and other factors. In forestry machinery variability of external factors in the interaction of the working bodies of the trees to be handled determines the complexity of the motion of individual points. In this regard, the hydraulic studies should be considered as controlled dynamical systems, consisting of a number of interconnected subsystems (hydraulic characteristics, the parameters of the object of labor, quality, characterizing the operator, etc.). This raises the need to build a design scheme that best reflects the real conditions of operation of the hydraulic drive. The article presents the mathematical model of the hydraulic boom arm that allows to explore it’s dynamic properties in a functional mode. A mathematical model of the hydraulic drive is a system of algebraic and differential equations describing the hydraulic actuator as a collection of disparate elements, hydraulic, mechanical and electrical. In developing the mathematical model of the hydraulic drive is used a uniform method of mathematical description of the mechanisms by means of hydro-chains, which allows to visualize the interaction of hydraulic elements that safeguard against errors in the preparation of differential equations.

Modular Multi-Rotor Helicopter Platforms

The results presented in this paper describe a practicable solution to multi-rotor platforms constructed and put together with standardized components to allow flexibility and customizability. The extensive utilization of universal parts supports an easy introduction of changes in case of necessary design alterations and speeds up the whole process when constructional changes are required. The research has been applied to a variety of special use multi-copters and has proven to be very useful. Further development will follow to secure subcomponents with necessary Ingress Protection ratings and even further optimize universal components. The constructional layout of multi-copters is relatively simple and usually consists of the main middle frame that houses control electronics, batteries and payload fastenings. Protruding boom arms have motors mounted in the tips and power cables running inside. The frame, payload and boom arms are generally fastened with hexagonal socket head cap screws, which means that assembling and disassembling takes a notable amount of valuable time when setting the UAV up on the field. For this reason, modularity and rapid assembling are needed.Fig. 1. Multi-rotors performing ice-bank and high-rise inspection