Excavator Arm Research Articles

Study on Hydraulic Circuit Simulation Based on MSC·EASY5 for the Arm of Excavator

In this paper, a hydraulic excavator is used as an example, and a model of the hydraulic circuit of the excavator arm is established using the graphical modeling method of EASY5. Through the simulation and analysis of the results, it can be seen that the simulation results can accurately simulate the dynamic characteristics of actual hydraulic circuit, and show the variation of the pressure in the hydraulic cylinder chambers. It not only provides a basis for the system performance analysis and the further improvement, but also provides a new method for the optimization design and overall performance analysis of the engineering machinery hydraulic system. And it also provides a new idea of design for the development of new product.

Proportional-Integral-Plus Control of Robotic Excavator Arm Utilising State-Dependent Parameter Model

This paper is concerned with the design of a control system for a robotic excavator known as the Lancaster University Computerised and Intelligent Excavator (LUCIE). A nonlinear proportional-integral-plus (PIP) control algorithm is developed for regulating movement of excavator arm. The nonlinear dynamics of the hydraulic driven arm is represented using the quasi-linear state-dependent parameter (SDP) model, in which the parameters are functionally dependent on other variables in the system. The model is subsequently utilised to develop a new approach to control system design, based on nonlinear PIP pole assignment. Implementation results demonstrate improved tracking performance of excavator arm in comparison with both linear proportional-integral-derivative (PID) and conventional (linearised) fixed-gain PIP control.

Modelling and remote control of an excavator

This paper presents the results of an on-going project and investigates modelling and remote control issues of an industry excavator. The details of modelling, communication, and control of a remotely controllable excavator are studied. The paper mainly focuses on trajectory tracking control of the excavator base and robust control of the excavator arm. These will provide the fundamental base for our next research step. In addition, extensive simulation results for trajectory tracking of the excavator base and robust control of the excavator arm are given. Finally, conclusions and further work have been identified.

Modelling of complex structures using superelements

The object of this investigation is a transient analysis of a complex structure. The modelling method using superelements is presented first. The working arm of a hydraulic excavator is then taken as a vehicle to illustrate the method, by employing substructuring (superelements) in a sample working cycle, where a pre-defined potential cutting force taken as a function of time is the major external load. The forces in all the joints of the working arm and the stress distribution in all the sub-structures have been obtained. Using the obtained results recommendations are given for the digging cycle that will produce lower dynamic loads.

COMPARISON OF CLASSICAL AND MODERN CONTROL APPLIED TO AN EXCAVATOR-ARM

The excavation of foundations, general earthworks and earth removal tasks are activities which involve the machine operator in a series of repetitive operations. Automation is likely to provide a number of benefits such as improving efficiency, quality and safety. However, a persistent stumbling block for system developers is the achievement of fast smooth movement of the excavator arm under automatic control. In this regard, the paper develops two very different design methods, a model-based, full state feedback approach and a classical frequency domain technique based on the Nichols chart. The advantages and limitations of these contrasting approaches are identified in terms of both performance and design effort.

Robust bucket position tracking for a large hydraulic excavator

The device we study is the excavation arm of a large hydraulic mining shovel having a multi-loop kinematic form. We describe an iterative algorithm that allows the position of the bucket to be tracked from measurements of the linear actuator extensions. The important characteristic of this algorithm is that it is numerically well-behaved when the linkage is close to singular configurations. While we focus on a specific device, the algorithm is easy to adapt to other multi-loop linkages.

Parameter Estimation for Excavator Arm Using Generalized Newton Method

A robust, fast, and simple technique for the experimental identification of the link parameters (mass, inertia, and length) and friction coefficients of a full-scale excavator arm is presented. This new technique, based on the generalized Newton method (GNM), estimates unknown individual parameters of the excavator arm dynamic equations. The technique can be used when the number of equations is different from the number of estimated variables. Using experimental data from a full-scale field Combat Engineer Excavator (CEE), the values of link parameters and friction coefficients are successfully identified. The identified parameters are compared with known values, and shown to be in agreement. The method is compared with the least square method, and shows that the GNM is better in terms of prediction accuracy and robustness to noise. Further, the joint positions predicted by the analytical model using the identified parameters are validated against different experimental trajectories, showing very good agreement. The experimental data was obtained in collaboration with QinetiQ Ltd. (Hampshire, U.K.). The technique presented in this paper is general and can be applied to any manipulator.

Proportional‐Integral‐Plus Control of an Intelligent Excavator

Abstract: This article considers the application of Proportional‐Integral‐Plus (PIP) control to the Lancaster University Computerised Intelligent Excavator (LUCIE), which is being developed to dig foundation trenches on a building site. Previous work using LUCIE was based on the ubiquitous PI/PID control algorithm, tuned on‐line, and implemented in a rather ad hoc manner. By contrast, the present research utilizes new hardware and advanced model‐based control system design methods to improve the joint control and so provide smoother, more accurate movement of the excavator arm. In this article, a novel nonlinear simulation model of the system is developed for MATLAB/SIMULINK©, allowing for straightforward refinement of the control algorithm and initial evaluation. The PIP controller is compared with a conventionally tuned PID algorithm, with the final designs implemented on‐line for the control of dipper angle. The simulated responses and preliminary implementation results demonstrate the feasibility of the approach.

Modelling and control of an unmanned excavator vehicle

This paper investigates the modelling and control of a full-scale excavator vehicle. A detailed analytical model for an unmanned excavator vehicle is developed. The model takes into account the kinematics and dynamics of the mobile platform (vehicle) and the excavation arm (links and hydraulic system). The model describes the dynamic relationship between the operator input commands (fuelling and joystick commands to excavation arm and steering lever) and the trajectories and forces of the excavator vehicle. The dynamic model of the excavation arm system is validated against measured data. The validation of the model is conducted in collaboration with QinetiQ Limited (the new science and technology company formed from the major part of DERA, the British Government's defence research and development organization). A unified model is important for design of control strategies, since in order to move the bucket of a mobile excavator, movements of the entire vehicle are required. A key requirement for automating the excavation task is automated trajectory tracking, and a proportional-integral-derivative (PID) controller for trajectory tracking is developed and tested. It is noted that even though the results presented in this paper are focused on a particular excavator, the research is generic and can be adapted to any tracked ground vehicle with an on-board closed-chain manipulator.

Modelling and control of an unmanned excavator vehicle

This paper investigates the modelling and control of a full-scale excavator vehicle. A detailed analytical model for an unmanned excavator vehicle is developed. The model takes into account the kinematics and dynamics of the mobile platform (vehicle) and the excavation arm (links and hydraulic system). The model describes the dynamic relationship between the operator input commands (fuelling and joystick commands to excavation arm and steering lever) and the trajectories and forces of the excavator vehicle. The dynamic model of the excavation arm system is validated against measured data. The validation of the model is conducted in collaboration with QinetiQ Limited (the new science and technology company formed from the major part of DERA, the British Government's defence research and development organization). A unified model is important for design of control strategies, since in order to move the bucket of a mobile excavator, movements of the entire vehicle are required. A key requirement for automating the excavation task is automated trajectory tracking, and a proportional-integral-derivative (PID) controller for trajectory tracking is developed and tested. It is noted that even though the results presented in this paper are focused on a particular excavator, the research is generic and can be adapted to any tracked ground vehicle with an on-board closed-chain manipulator.

A Virtual Environment for the Simulation and Programming of Excavation Trajectories

An excavator simulator has been developed to facilitate the training of human operators and to evaluate control strategies for heavy-duty hydraulic machines. The operator controls a virtual excavator by means of a joystick while experiencing visual and force feedback generated by environment and machine models. The simulator comprises an impedance model of the excavator arm, a model for the bucket-ground interaction forces, a graphically rendered visual environment, and a haptic interface. This paper describes the simulator components and their integration.

Identification of inertial and friction parameters for excavator arms

A novel yet simple approach for experimental determination of the link (mass and inertia-related) parameters and friction coefficients is developed for a typical excavator arm. The parameters are needed for indirect measurement of the external forces, compensation for the link weights in the operator's hand in a force-feedback teleoperation setup, impedance control of the arm, simulation of the manipulator dynamics, and model-based fault detection. Treating the machine arm as an open kinematic chain, its dynamic equations are presented symbolically. The static torque equations are derived from these equations and the gravitational parameters are defined accordingly. A new method for decoupled estimation of the gravitational parameters from static experiments is presented. Furthermore, the arm dynamics are expressed in a form which is linear in the inertia and friction-related parameters. The results obtained show that the identified model predicts the joint torques, in both static and dynamic conditions, with a very good accuracy.

Improvement of Damping Characteristics of Hydrostatically Driven Hydraulic Excavator.

This paper presents a system concept of a hydro-statically driven hydraulic excavator. In this system, pumps and actuators are connected each other. Then, the speed of actuators is controlled by operation of pump delivering flow rate. Herein, a hydraulic excavator has 7 actuators and 4 pumps, and the connection/disconnection of each pump and actuator is controlled by 3×4 directional control valves. Microcomputers execute the following controls : maximum pressure limiting, pump absorption power control for prevention of engine stall, transient vibration damping, maximum acceleration limiting and resolved motion rate control of the excavator's arm. Furthermore, this paper shows method for improvement of damping characteristics of the hydrostatically driven hydraulic excavator. This method does not necessarily create additional energy loss because it is controlled by operation of the pump delivering the flow rate.

Pressure Cutoff Control of Hydrostatically Driven Hydraulic Excavator.

This paper first presents a system concept of a hydrostatically driven hydraulic excavator. In this system, pumps and actuators are connected each other. Then, the speed of actuators is controlled by the pump flow rate. Herein, a hydraulic excavator has 7 actuators and 4 pumps, and connection/disconnection of each pump and actuator are controlled by 3x4 directional control valves. Microcomputers execute the following controls : maximum pressure limiting (pressure cutoff control), pump absorption power control for prevention of engine stop and suitable power distribution to pumps, transient vibration damping, maximum acceleration limiting and resolved motion rate control of the excavator's arm. Furthermere, in this paper, we report the experimental study of pressure cutoff control which is a basic function for energy saving in a hydrostatically driven hydraulic excavator.

Service loading of work attachments of hydraulic excavators: Sobczykiewicz, W. Proc. Conf. Fatigue Design, Helsinki, Finland, 19–22 May 1992 (Technical Research Centre of Finland, Vuorimiehentie 5, PO Box 42, SF-02151 Espoo, Finland) 1992 pp 299–310

The device we study is the excavation arm of a large hydraulic mining shovel having a multi-loop kinematic form. We describe an iterative algorithm that allows the position of the bucket to be tracked from measurements of the linear actuator extensions. The important characteristic of this algorithm is that it is numerically well-behaved when the linkage is close to singular configurations. While we focus on a specific device, the algorithm is easy to adapt to other multi-loop linkages.

Application of structural optimization using finite elements

This paper describes the theoretical basis of SDRC's redesign package, Optisen. The use of the program is illustrated using three realistic applications. First, the design of a plastic seat tub for strength requirements. Second, the design of an excavator arm for stiffness and strength requirements. Third, the modification of a helicopter for dynamic response.