Lift Arm Research Articles

Integrated Kinematics Optimization and Strength Analysis for a Wheel Loader Boom Mechanism

Based on the kinematics optimization method integrated in ADAMS, the mechanism parameters of the loader boom for a wheel loader are designed to keep the variety of the pylon rotation angle as smaller as possible during the loader boom lifting or falling process. A rigid-flexible coupled model is developed to analyze the dynamic stress of the lift arm and the contact element methodology is adopted to model the coaxial rotary joints connections. The results simulated by ADAMS indicate that the optimization is well fulfilled. Integrated kinematics optimization and strength analysis provide the well basis for further optimization of whole structure.

Development of a computer program for the path generation of tractor hitch points

In the vertical longitudinal plane of a tractor, the three-point hitch system is a six-bar mechanism that can be designed and modelled as two distinct four-bar linkages sharing two links. A Newton–Raphson solution for the four-bar linkage has been applied to a three-point hitch system of tractor to determine the range of movement of the lift arm and generate the path of motion of lower and upper hitch points in the movement range of the hitch. The algorithm was executed as a program in MATLAB. The program has the ability to generate the path of motion of lower; upper and virtual hitch points, determine the geometric performance parameters of the hitch system, and identify the variations in the quality of force transmission by the linkage system throughout the range of hitch movements for 165 different groups of hitch dimensions available in the Nebraska tractor test reports. Application of the program for searching improved design solutions for the existing hitch system of a tractor was demonstrated. The program has the potential to be used in any search-based techniques for optimisation of the dimensions of three-point hitch systems for tractors. In addition, variations in length of links and spatial location of their pivot points were studied for various categories of hitches. The range of values of link lengths and the spatial location of their pivot points reported here can be used for defining the design space during the optimal dimensional synthesis of tractor three-point hitch systems.

Processing and utilization of coconut wood in Kerala

The coconut palm (Cocos nucifera L.) is the “tree of life” and known as “porcupine wood”. All parts of the coconut wood can be manufactured into commercial products. The wood is hard and durable; volumetric shrinkages are mostly smaller. The tree is non-branching and free of knots and can be used as decorative wood. No distinguishable separation between sapwood and heartwood. The logs are cut into 4–6 m length depending on height and soundness of the tree. Most efficient and least expensive system of log extraction is the use of agricultural tractor with a towing bar fitted to the hydraulic lift arms. Loading may be done by manually and by cross hauling with a skidding tractor or with a hydraulic front-end loader. Timber should be graded as hard, intermediate or soft corresponding to high, medium and low densities. Coconut wood is used in construction, furniture, high-value products, charcoal, chemicals, pulp and paper. Coconut wood utilization can supplement the supply of raw materials for the wood industry and provide low-cost and durable construction materials for housing programmes in the state and for export. Due to the low price of coconut wood, it becomes popular among the middle and low-income groups, and used as a substitute for commercially known wood species to overcome the inadequate supply of logs and help to conserve the remaining forests in Kerala.

Comparison between Multiobjective Population-Based Algorithms in Mechanical Problem

The objective of this paper was to perform a comparative study among multiobjective optimization methods on practical problem by using modeFRONTIER optimization software, to determine the efficiency of each method. In order to measure the effectiveness and competence of each method, the lifting arm problem was chosen from the literature [1]. Two numerical performance metrics and one visual criterion were chosen for qualitative and quantitative comparisons:(1) the variance of solution distribution in the Pareto optimal regions, (2) the ratio between the number of resulting Pareto front members to total numbers fitness function calculations which is denoted by hit rate [2], and lastly (3) graphical representation of the Pareto fronts for discussion. These metrics were chosen to represent the quality, as well as speed of the algorithms by ensuring well extends solutions. The definition of the variance as the sum of the square difference between the distance of each Pareto solutions and the average distance between Pareto solutions, over the total number of Pareto solutions. Comparisons among the results obtained using different algorithms have been performed to verify their performance. The experiments carried out indicate that FMOGA-II obtains remarkable results regarding all metrics used.

The Design of a Patient Transportation Robot's Lifting Arms Considering Comfort and Safety without the Presence of a Sheet

A transportation robot's lifting arms have an effect on the comfort and safety of patients. Improved arms have been designed through dynamic and static analyses to increase safety if a sheet not present on the lifting arms. To design the lifting arms, experimentation is very helpful, however, it is difficult and dangerous to experiment on patients; therefore, a simple human model was made and used for the dynamic analysis. Through the dynamic analysis results, a safe width and comfortable location for the lifting arms were determined. The thickness was then determined by static analysis and optimum design. In addition, tests have been conducted to confirm comfort and safety by deploying the designed lifting arms onto a transportation robot.

Study on the Three Point Hitch and PTO of Available Tractors for Rotary Implements

The tractor industry is segmented on the basis of the power of the tractor engine in terms of horse power. The innovation of three point linkage system and hydraulic system control has changed the whole trend of design of farm tractors and implements. The three-point hitch is made up of several components including the tractor's hydraulic system, attaching points, the lifting arms, and stabilizers. Number of tractor makes and implement manufacturers are causing problem in inter hitching. This study is useful for attaching one implement to multiple tractors. In this study, different tractors were taken into consideration and divided into five categories on the basis of their horse power. The objective of this study was to find the variations in dimensions of three point hitch and PTO of all available tractors, so as to find out a range for standardization of three point hitch and PTO system for all hp tractors. The present study revealed that hitch geometry and PTO parameters of all hp categories of tractor fall in a certain range. It also indicated that a micro level study of these parameters is required to squeeze that range or to find a particular value of a particular parameter so as to standardize it.

A RISK ANALYSIS OF STEVEDORING OPERATIONS IN SEAPORT CONTAINER TERMINALS

This research is a study of container terminals in Kaohsiung Harbor and investigates risk management in the loading and unloading of container terminals. The study shows that the top three factors associated with severity of accident risk are: “Moving the crane without raising the lifting arm of the gantry crane, resulting in damage to the pilot’s compartment,” “Transferring containers direct to the trailers,” and, “As a result of climatic factors (typhoons), the facility takes no action to prevent collisions.” The top three factors associated with frequency of accident risk are, “Ships go by and waves cause a declined-body, raised prow or changed slipped cable,” “An overweight container in unbalanced loading causes impact in moving containers,” and “Parking trailers do not keep a distance from gantry crane.” Finally, through the carrying out the department of risk management to draft out the risk strategies. Under the rational cost could help the terminal operator reduce the effect of container terminals which may be caused by the uncertainty of accident risks to ensure security of operations.

Prospective study on shoulder symptoms among kitchen workers in relation to self-perceived and observed work load

Objectives:To study the occurrence of shoulder symptoms among professional kitchen workers, and whether reduction in self-perceived and observed physical work load decreases future symptoms.Methods:In this prospective study conducted in 2002–2005...

A Pneumatic Device for Lifting Containers in Plant Water Use Studies

Direct gravimetric determinations of whole‐plant water use in container studies can be time consuming due to the tremendous labor required to physically lift containers for placement on weighing scales. Our objective was to design and construct a container‐weighing system that could be rapidly deployed and required little physical labor. A custom‐made support frame, equipped with a pneumatic lifting cylinder connected to a hanging scale, was constructed to lift large plastic containers (45 L) filled with a coarse sandy medium (>70 kg when saturated with water). Custom lifting arms designed to catch the handles of the plastic containers were constructed for attachment to the scale. The support frame weighing apparatus was positioned over the container, and the pneumatic lifting cylinder was activated only after lifting arms had been attached to the plastic container. As many as 25 large plastic containers could be weighed per hour with this system. The weighing system has been successfully used to follow plant water use patterns over time.

Aluminium foams for lighter vehicles

Metallic foams have become an attractive research field both from the scientific viewpoint and the prospect of industrial applications. Various methods for making such foams are available. Some techniques start from specially prepared molten metals with adjusted viscosities. Such melts can be foamed by injecting gases or by adding gas-releasing blowing agents which decompose in-situ, causing the formation of bubbles. A further way is to start from solid precursors containing a blowing agent. These can be prepared by mixing metal powders with a blowing agent, compacting the mix and then foaming the compact by melting. Alternatively, casting routes can be used to make such precursors. The unique properties of foams promise a variety of applications in vehicle design ranging from light-weight construction, impact energy absorption to various types of acoustic damping and thermal insulation. Four applications are discussed, including a lifting arm on a lorry, an automobile and a train crash box, and a motor bracket.

Development of an Autonomous Transfer Machine Using Pneumatic Actuators

In this paper, we propose a new type of Autonomous Transfer Machine (ATM) by making use of pneumatic actuators such as pneumatic cylinders and bellows actuators. In the lifting part, the lifting arm which is constructed with a cylinder is rotated by antagonized bellows actuators. Moreover, the support part that a user leans on is supported by antagonized bellows actuators. Since the bellows actuator has a force sensing ability that acts both a force sensor and an actuator, external force that the user leans on the supporter can be estimated. In the standing-up motion, the support part is controlled by both the inclination of the support part and the force difference between holding force and supporting force. Therefore, the lifting trajectory of the supporter can be realized by the posture of the user. In this paper, we clear the effectiveness of the ATM with the standing-up motion from experimental results.

Applying virtual reality techniques to the interactive stress analysis of a tractor lift arm

The objective of this research is to examine the challenges of applying virtual reality techniques to the interactive stress analysis of a tractor lift arm. NURBS-based free form deformation, finite element analysis, sensitivity analysis, collision detection, and virtual reality are combined to create an interactive environment for designers to view and modify part shape, evaluate the resulting stresses, and check for interference of the new part shape and surrounding parts in real-time. These methods are implemented using a surround screen virtual environment where the part of interest and associated geometry surrounding that part are displayed together using stereo projection to provide a three-dimensional view of the assembly.

Electro-hydraulic tillage depth control system for rotary implements mounted on agricultural tractor Design and response experiments of control system

A tillage depth control system for rotary implements mounted on an agricultural tractor was designed and constructed to improve accuracy of tillage depth. The control system was composed of five main units: (1) a detecting unit to measure the tilting angle (position) of the lift arm, the pitching angle of the tractor and heights of sensors from ground surface, (2) a controlling unit, (3) a hydraulic unit to operate a three-point hitch linkage by a lift arm cylinder, (4) a three-point hitch linkage and rotary implements, and (5) a setting unit to put the reference tillage depth and a dead zone into the control circuit. The tillage depth was controlled by an on/off operation of a solenoid valve, of which time was proportional to the controlling time. Experiments to evaluate the response characteristics of the control system were conducted under various engine speeds, i.e. various flow rates of hydraulic oil, various tillage depths and some input frequencies. The results of the response experiments of the control system are discussed in this paper.

VarioLift retraction system for laparoscopy without pneumoperitoneum

SummaryThere are adverse effects due to the pneumoperitoneum during laparoscopic surgery, therefore the question of alternative procedures for retracting the abdominal wall has increasingly been discussed. So far, various systems which mechanically retract the abdominal wall have been introduced. However, due to their complicated design or limited visibility, they have not become popular. The modular retraction system (VarioLift, AESCULAP) consists of two components — a retractor for lifting the anterior abdominal wall and a hold-down device for compressing bulging internal organs. Both parts of the abdominal wall retractor are inserted in sequence through a 1.5 cm minilaparotomy and are, after being connected to each other, fixed to a mechanical lifting arm. The parts are available in various sizes and shapes, so that the retractor can be adapted to the respective abdominal quadrant and the anatomic situation of the patient. After lifting the anterior abdominal wall, the hold-down device is inserted, unfolded and positioned to hold down bulging internal organs.In contrast to other retraction systems, the VarioLift system allows the anterior abdominal wall to be raised in a dome-shaped fashion, offering good lateral visibility. The construction of the system, including the minilaparotomy, does not take any longer than the installation of a pneumoperitoneum.

A min-max problem of optimal actuator placement for lifting

SummaryThe paper addresses the following problem: for a three-bar lifting linkage, find the locations of the two ends of the actuated link so as to minimize the maximum value of the force seen by the actuator over a specified range of arm angular positions. A simple analytical solution to this min-max problem is given, showing that the optimal locations are with the actuated link perpendicular either to the fixed link or to the lifting arm, when the arm is in a horizontal position. The method can be used to optimize the actuation of robots, doors, platforms, landing gears, etc., and allows to account for actuator length constraints. It can be extended also to Stewart's platform-type spatial manipulators.

Gasless Laparoscopic Gastrostomy

Percutaneous endoscopic gastrostomy (PEG) is the procedure of choice in the nutritional management of patients requiring gastrostomies. Laparoscopic gastrostomy is usually performed when PEG is contraindicated, for example, in patients with esophageal strictures, large gastric tumors, or a history of multiple abdominal surgery. We report herein a case of gasless laparoscopic gastrostomy performed for carcinoma associated with a severe respiratory distress syndrome in a malnourished patient with a tight esophageal stricture. The gasless technique uses the Laparolift System (Laparolift, Origin Medsystem, Inc.), a device composed of a fan-shaped retractor and a mechanical lifting arm that produces an abdominal wall distention resembling a truncated pyramid. Gasless laparoscopy was a safe alternative approach to CO2 pneumoperitoneum in this patient.

Gasless laparoscopy in abdominal surgery.

Pneumoperitoneum, as a necessary precondition of laparoscopic procedures, represents a restriction of the surgeon's freedom of movement and can lead to rare but typical complications. We describe our first experiences with laparoscopic surgery without using pneumoperitoneum. Under direct vision and digital control a fan-formed wall retractor, which is attached to an electric lift arm, is introduced into the abdominal cavity. After raising the abdominal wall, the scope is introduced through the same access and the laparoscopic procedure can be started without the technical and physiopathological problems which may occur using a pneumoperitoneum. In this gasless laparoscopic procedure, simple valveless trocars and instruments can be used. Furthermore, an unlimited suction can be obtained without a loss of exposure. During anesthesia, neither increased ventilation nor increased ventilation pressure is necessary, and the surgeon has increased freedom of action. Not only special laparoscopic instruments, but the conventional instruments, used in open surgery, can also be employed in gasless laparoscopy. In this way we performed gasless laparoscopic surgery on 54 patients: cholecystectomy (n = 37), abdominal exploration for NSAP (n = 5) or tumor staging (n = 4), fenestration of liver cysts (n = 5), and appendectomy (n = 3). We did observe three wound infections as related complications. Six times, we had to change the surgical procedure. Compared to the traditional procedure with a CO2 pneumoperitoneum, the results of the first gasless procedures demonstrate potential advantages.

A remote manipulator for forestry operation

The remote manipulator described consists of two arms: a 3-DOF main lifting arm (aerial device), and a 6-DOF robot manipulator (treejib) mounted at the upper end of the aerial device. Each arm is single-joint rate controlled, with the reference joint rate being proportional to the corresponding joint displacement of a corresponding hand controller. Both controllers are kinematically equivalent to each of the two arms. Two of the treejib joints are instrumented for position feedback, and the corresponding hand controller joints are motorized and also position controlled. This ensures that no excessive force is exerted on the tool during contact with the branches. The system is of a master-slave rate controlled force reflective type. The design presented has novel features such as a quick connect-disconnect coupler for hydraulic tools and a force reflective master in a form of a small kinematic replica of the slave. The system has been extensively field tested. The results were very promising, however several modifications to the basic concept used to automate the specific operations are necessary. >

Concept and model experiments on automatic shoveling of rocks from the rock piles

Abstract This paper is concerned with the robotics of the shovel dozer. One methodology to distinguish between the rock pile and the huge rock was proposed in this study. The concept of this method is based on the difference of the time history of the force acting on the lift arms of the shovel dozer model. By using this model, two kinds of experiment on shoveling the rocks were carried out with changing the RPM of the motor. It was confirmed that stable shoveling was conducted.

A method of investigating rod motion in a laboratory rod mill

The work reported here measured the position of a rod in a laboratory mill at 1/25 second time intervals using an active light source in the rod and a video camera. The detailed picture of the charge movement which was obtained was used to calculate mill power using rod lift and torque arm models. Theoretical analysis showed that the presence of slip does not change the mill power because the lower power required for lift in the presence of slip is counterbalanced by the extra power required to overcome friction. Power predicted from a simple slip surface treatment is not correct because media emerging through the slip surface has to rise further to over-ride media emerging lower in the surface. The powers calculated from the lift model and the torque arm model (assuming all rods contribute to torque) were almost identical, but did not predict the correct variation in power with mill rotational speed. It was concluded that a valid fundamentally based prediction of mill power is still not available.