Robotic Mechanical Systems Research Articles

Gantry Robot Dynamic Analysis Based on Lagrange’s Motion Equation

The dynamic problem is defined as the way the motion of the robot arises due to the torques and forces applied at the joint by the actuators. The motion undergone by robotic mechanical system should be as, a rule, as smooth as possible, abrupt changes in position, velocity, and acceleration should be avoided. Indeed, abrupt motions require unlimited amounts of power to be implemented, which the motors cannot supply because of their physical limitations. In this paper an analytical solution for the dynamics of 3 DOF gantry robot presented to achieve those goals, so our aims is to model the dynamics of gantry Robot for simple pick and place application. Equations of motion are derived using the Lagrange equations of the second order, the dynamical model of robot was developed, and the gantry robot system was modeled in SOLIDWORKS software environment and it was simulated using ADAMS software. The manipulator is composed by four basic modules defined as module X, module Y, module Z and terminal arm, where is connected the end-effector.

Adaptive splitbelt treadmill walking of a biped robot using nonlinear oscillators with phase resetting

To investigate the adaptability of a biped robot controlled by nonlinear oscillators with phase resetting based on central pattern generators, we examined the walking behavior of a biped robot on a splitbelt treadmill that has two parallel belts controlled independently. In an experiment, we demonstrated the dynamic interactions among the robot mechanical system, the oscillator control system, and the environment. The robot produced stable walking on the splitbelt treadmill at various belt speeds without changing the control strategy and parameters, despite a large discrepancy between the belt speeds. This is due to modulation of the locomotor rhythm and its phase through the phase resetting mechanism, which induces the relative phase between leg movements to shift from antiphase, and causes the duty factors to be autonomously modulated depending on the speed discrepancy between the belts. Such shifts of the relative phase and modulations of the duty factors are observed during human splitbelt treadmill walking. Clarifying the mechanisms producing such adaptive splitbelt treadmill walking will lead to a better understanding of the phase resetting mechanism in the generation of adaptive locomotion in biological systems and consequently to a guiding principle for designing control systems for legged robots.

A stability-based mechanism for hysteresis in the walk-trot transition in quadruped locomotion.

Quadrupeds vary their gaits in accordance with their locomotion speed. Such gait transitions exhibit hysteresis. However, the underlying mechanism for this hysteresis remains largely unclear. It has been suggested that gaits correspond to attractors in their dynamics and that gait transitions are non-equilibrium phase transitions that are accompanied by a loss in stability. In the present study, we used a robotic platform to investigate the dynamic stability of gaits and to clarify the hysteresis mechanism in the walk-trot transition of quadrupeds. Specifically, we used a quadruped robot as the body mechanical model and an oscillator network for the nervous system model to emulate dynamic locomotion of a quadruped. Experiments using this robot revealed that dynamic interactions among the robot mechanical system, the oscillator network, and the environment generate walk and trot gaits depending on the locomotion speed. In addition, a walk-trot transition that exhibited hysteresis was observed when the locomotion speed was changed. We evaluated the gait changes of the robot by measuring the locomotion of dogs. Furthermore, we investigated the stability structure during the gait transition of the robot by constructing a potential function from the return map of the relative phase of the legs and clarified the physical characteristics inherent to the gait transition in terms of the dynamics.

GLOBALLY ROBUST ENGINEERING DESIGN USING COMPLEXITY RULES

The paper aims at defining some complexity indices that would help designers of robotic mechanical systems to develop their goods with a globally robust design. Complexity is a relevant criterion in a globally robust design problem. Formerly a philosophical concept, it is nowadays well defined mathematically, but mainly used in computer science. However, design complexity is not defined yet in the literature. First, the notion of globally robust design and a design process model are set forth. Then, four design complexity indices are introduced. The first uses the notion of variance, the second is based on entropy, the third uses the notion of spectral richness, and the last one uses the notion of spectral noise. Finally, these four indices are compared by means of an analysis of the complexity of several distributions of subproducts.

2A1-K12 センサ情報に基づく蛇型ロボット環境適応移動SR-Iの開発(環境適応メカニズムと制御)

Biologically inspired snake-like robot has been widely studied for its various motion patterns. To achieve autonomous adaptive locomotion, a sensor-driven snake-like robot has been developed. Such robot can achieve self-adaptive locomotion by coupling sensory information with the motion control system. The design of the mechanism and control system of this sensor-driven snake robot is presented in the paper. Based on the sensory information, the implementations of terrain-adaptive locomotion and collision-free locomotion are investigated respectively. The performance of the collision-free locomotion is verified by conducting an experiment on the robot in an environment with obstacles.

Simulation of friction stir welding using industrial robots

PurposeThe purpose of this paper is to establish a model‐based framework allowing the simulation, analysis and optimization of friction stir welding (FSW) processes of metallic structures using industrial robots, with a particular emphasis on the assembly of aircraft components made of aerospace aluminum alloys.Design/methodology/approachAfter a first part of the work dedicated to the kinetostatic and dynamical identification of the robotic mechanical system, a complete analytical model of the robotized process is developed, incorporating a dynamic model of the industrial robot, a multi‐axes macroscopic visco‐elastic model of the FSW process and a force/position control unit of the system. These different modules are subsequently implemented in a high‐fidelity multi‐rate dynamical simulation.FindingsThe developed simulation infrastructure allowed the research team to analyze and understand the dynamic interaction between the industrial robot, the control architecture and the manufacturing process involving heavy load cases in different process configurations. Several critical process‐induced perturbations such as tool oscillations and lateral/rotational deviations are observed, analyzed, and quantified during the simulated operations.Practical implicationsThe presented simulation platform will constitute one of the key technology enablers in the major research initiative carried out by NRC Aerospace in their endeavor to develop a robust robotic FSW platform, allowing both the development of optimal workcell layouts/process parameters and the validation of advanced real‐time control laws for robust handling of critical process‐induced perturbations. These deliverables will be incorporated in the resulting robotic FSW technology packaged for deployment in production environments.Originality/valueThe paper establishes the first model‐based framework allowing the high‐fidelity simulation, analysis and optimization of FSW processes using serial industrial robots.

Adaptive Robotic Mechanical Systems: A Design Paradigm

This paper aims at developing a general framework for the use of the concept of adaptive mechanical system in the design of advanced robotic devices. The concept of adaptive mechanical system is first formalized. A design methodology is then proposed in order to formulate the associated design paradigm, based on the fundamental principles of mechanics. Finally, examples of adaptive robotic mechanical systems taken from the literature are presented in order to illustrate the application of the general design methodology.

情報収集型レスキューロボット「Baby II」における自己復帰メカニズム(レスキューシステム・レスキュー工学5)

情報収集型レスキューロボット「Baby II」における自己復帰メカニズム(レスキューシステム・レスキュー工学5)

A fuzzy adaptive variable structure controller with applications to robot manipulators

A new adaptive fuzzy control algorithm is developed in this paper, which has a regular fuzzy controller and a supervisory control term. This control algorithm does not require the system model, but has stability assurance for the closed-loop controlled system. The design is simple, in the sense that both the membership functions and the rule base are simple, yet generic. It can be applied to a large class of robotic and other mechanical systems.

鉄管内走行ロボットの開発

This paper describes a new mechanism, communication system, and vision system of an in-pipe inspection robot. To date, inspection robots have had such limitations as mobility of the robot to turn in a T-shaped pipe or move in a plug valve. The new mechanism based on our dual magnetic wheels overcomes these limitations without difficulty in control. This dual mechanism, resembling a crawler, enables the robot to climb over sharp obstacles like sleeve and dresser joints. Another drawback of earlier robots is that the friction between the pipe and the cables for communication and power supply makes it difficult to move a long distance. A fiber-optic communication system can reduce friction. The spooler of the fiber-optic communication cables and batteries are mounted on the robot and the cables are rolled and unrolled when the robot is going forward and backward, respectively. The new vision system has been significantly miniaturized, enabling it to clearly view and inspect the pipe welds underneath the robot while gazing ahead for navigation. The reflection of slit light made by a light-emitting diode and a cylindrical lens is used to diagnose the pipe weld.An experimental inspection robot has been successfully made to confirm the efficiency of the new mechanism and the vision system.

Special Issue on Advanced Maintenance Robots

At present, inspection and maintenance operations on various types of pipelines, structures, and others are carried out manually by human operators. Such operations are often performed, in general, under adverse environments such as high places and narrow areas. In addition, fire fighters in blazing high-rise buildings may be subjected to dangers involving high places and fires. Moreover, the robotization of grinding work in factories, for example, require a large number of empirical technologies. In order to mechanize tasks under such adverse environments and under special working conditions, research has been conducted, including studies of mobile mechanisms on inner walls and outer walls of piping, on wall surfaces of structures, etc. or studies of force control methods. Under these circumstances, this issue will be specialized in technical progress of various types of maintenance robots. First, a navigation system of a wind quantity inspection robot using a fuzzy neural network will be discussed by Messrs. Fukuda and Abe. Next, a report will be given by Messrs. Ishikawa and Shiire on the mechanism and functions of a pile recovery robot for large-diameter pipes, with a view to carrying out cleaning work inside cooling water pipes of electric power generation plants, as well as on its field testing. Furthermore, Messrs. Kawaguchi and Yoshida will be asked to report on the mechanism of an inspection robot for use on the inner surfaces of gas piping buried in the ground. In addition, a discussion will be carried out by Messrs. Naruse and Takada on the mechanism and fire extinguishing capability of a hybrid robot system for use in combatting fires in high-rise buildings. Moreover, Messrs. Ozaki and Jinno will be discussing the mechanism and force control system of a grinding robot. In addition, a discussion will be carried out by Messrs. Hosokai and Hara regarding the motion function of a piping inspection robot having a lazy tong mechanism and also regarding its piping test results. Finally, Messrs. Amano and Kakikura will be called upon to give a discussion concerning a robot for carrying out exfoliation of finishing materials on the outer walls of structures and its exfoliation. In closing, it is hoped that this special issue will be of some help in the future when such maintenance robots are developed.

Dynamics modeling of robotic manipulators using an artificial neural network

Dynamics modeling is important for the design, analysis, simulation, and control of robotic and other computer-controlled mechanical systems. The complete dynamic modeling of such systems involves the computationally intensive solution of a set of non-linear, coupled differential equations. Artificial neural networks are well suited for this application due to their ability to represent complex functions and, potentially, to operate in real time. The application of an artificial neural network to dynamics modeling of robotic systems is investigated. The Cerebellar Model Arithmetic Computer (CMAC) is employed. A hybrid implementation of CMAC is proposed to allow use of the model for either simulation or control of robotic manipulators. The success of the simulated results and the accuracy of the generated outputs after a few training cycles demonstrate great promise for further development of the method and its implementation in control systems. © 1994 John Wiley & Sons, Inc.

Identification of Robots Dynamics

The motion of a robotic mechanical system is described by a set of highly coupled and non linear equations. Dynamic control techniques have been proposed to take into account the exact equations of motion. A major problem to implement these algorithms on real robots is that they need accuracy identification of parameters of the dynamic model. Recently and independently, some papers have the common idea to estimate the inertial parameters by the use of a dynamic model linear whith respect to the inertial parameters. The identification of the inertialparameters are carried out by the use of the standard least squares techniques. This paper presents a study about the efficiency of this technique of estimation especially when the measurements are noisy. An application by simulation will be given on a SCAR A robot by the use of an iterative least squares method.

ロボット機構系の設計

ロボット機構系の設計

Computer graphics as an aid to a robot dynamical simulation analysis

This paper describes the results of an attempt to outline a computer graphic system that permits the generation and spatial transformations of polyhedric solids. This system was created to provide a simulator with enough visual resources to clearly represent the dynamical behavior of a robot mechanical system submitted to some control procedures. It has been adapted to a system with limited graphical resources. Considerations of other applications for this graphical feature are also outlined.