Industrial Articulated Robot Arms Research Articles

Teleoperation of robot arm with position measurement via angle-pixel characteristic and visual supporting function

In this paper, a teleoperation system of a robot arm with position measurement function and visual supporting function is developed. The working robot arm is remotely controlled by the manual operation of the human operator and the autonomous control via visual servo. The visual servo employs the template matching technique. The position measurement is realized using a stereo camera based on the angle-pixel characteristic. The visual supporting function to give the human operator useful information about the teleoperation is also provided. The usefulness of the proposed teleoperation system is confirmed through experiments using an industrial articulated robot arm.

다관절 로봇을 이용한 3차원 곡면가공 방안에 관한 연구

NC machines are generally used for machining operations because of their position accuracy, path accuracy, and machining reaction force. However, some NC machines require a very large space and are expensive. Recently, industrial articulated robot arms with large handling capability and wrist torque have been developed and the corresponding sensor technology has been improved. A machining robot for three-dimensional large curved objects was developed on the basis of an automatic-path-generation method. A self-position-compensation method with a laser displacement sensor was adopted for the six-axis robot developed, because the large articulated robot arms had poor position accuracy. An automatic-path-generation method using specific points was adopted to reduce the number of teaching points and time. In order to determine the proper machining conditions, various machining conditions such as tool rotation speed, cutting angle, cutting depth, and tool moving speed, were evaluated.

フォースフリー制御を用いた産業用多関節ロボットアームの遠隔操作システム

A lot of robots are operated in industry. In this paper, teleoperation system of industrial articulated robot arms is proposed. Both of the operation side and the work side, the industrial robot arms are used. In the operation side, the forcefree control technique is adopted for realization of the passive motion due to the influence of external force, and in the work side, the contour control is adopted for realization of the same motion of the robot arm in the operation side. The information of the motion of the robot in the operation side is sent to the work side through network. The method can realize replacement of the roles in the operation side and the work side only by changing the control techniques. The effectiveness of the proposed teleoperation system is confirmed by the experimental results using actual robot arms.

Forcefree control with independent compensation for industrial articulated robot arms

Forcefree control of robot manipulators so far has been the passive motion of the arm due to the influence of external force under ideal conditions of zero gravity and zero friction, whereas this paper demonstrates forcefree control under assigned friction, gravity and inertia. The effectiveness of the proposed forcefree control with independent compensation is confirmed by comparing the experimental results with simulation results. Comparisons of the forcefree control with independent compensation to the other force control methods are also presented.

A hybrid neuro-inverse control approach with knowledge-based nonlinear separation for industrial nonlinear system

This brief presents a general methodology of controller design by the hybrid neuro-inverse control with knowledge-based nonlinear separation for industrial nonlinear systems. In industrial nonlinear systems, various kinds of uncertainties may cause serious deterioration of system performances. Unfortunately, these uncertainties are usually difficult to identify and compensate from the entire system point of view. With using the knowledge-based nonlinear separation, nonlinear dynamics of a nonlinear system is possibly separated into the input-output nonlinear static part and the nonlinear dynamic part to form a nonlinear separation structure. Hence, uncertainties in the nonlinear system are bounded in the nonlinear dynamic part. In the proposed hybrid neuro-inverse control method, the input-output nonlinear static part is controlled by an inverse controller. A neurocontroller with a rigidly defined and trained neural network using available prior knowledge of the nonlinear system is constructed for the control of the nonlinear dynamic part. Owing to using the knowledge-based nonlinear separation, the neurocontroller is only needed to control a part of the original nonlinear dynamics of industrial nonlinear systems contaminated by uncertainties. The structure of the neural network employed by the neurocontroller becomes simpler and the consumption of time in training is reduced. Meanwhile, system performances of the nonlinear system can be improved. In this brief, with two typical control problems in industries, i.e., high-precision contour control of industrial articulated robot arm (IARA) and outlet working fluid heat rate control of evaporator in energy conversion plant, the proposed method was explained clearly. The experimental and simulation results demonstrated the generality, practicality and significant potential of this method for realizing the high-performance control of industrial nonlinear systems.

FORCEFREE CONTROL WITH INDEPENDENT COMPENSATION FOR INDUSTRIAL ARTICULATED ROBOT ARM

In this paper, the concept of forcefree control is extended to realize flexible motion of industrial articulated robot arms under the virtual operational circumstances such as free of inertia, friction and gravity through independent compensation of inertia, friction and gravity. The forcefree control with independent compensation was verified with an experimental study of an actual industrial robot arm.

Forcefree Control with Independent Compensation of Inertia, Friction and Gravity for Industrial Articulated Robot Arms

Forcefree control is a kind of robot arm control method as if it existed under non-gravity and non-friction conditions. In this paper, the forcefree control with independent compensation was proposed, in which inertia, friction and gravity torque were compensated independently. The proposed forcefree control with independent compensation was assured by simulation and experimental results. Furthermore, experimental results of pull-out-work and direct teaching of an industrial articulated robot arm were shown as applications of the proposed method.

High Speed and High Accuracy Control of Industrial Articulated Robot Arms with Jerk Restraint by Spline Interpolated Taught Data

In industrial robot arms, high speed and high accurate operation is required. However in case of high speed operation, it often arises high jerk, i, e., rapid change of acceleration. Jerk causes deterioration of control performance such as vibration of a tip of a robot arm. It is, therefore, important to reduce jerk during robot arm operation. In this research, spline interpolation is used to reduce jerk under torque and speed constraints. Effectiveness of the proposed method was assured by experimental results and simulation results of an actual robot arm.

Orthogonal Type Forcefree Control by Considering Following Locus for Industrial Articulated Robot Arm

Orthogonal Type Forcefree Control by Considering Following Locus for Industrial Articulated Robot Arm

Human direct teaching of industrial articulated robot arms based on force-free control

Force-free control produces motion in a robot arm as if it were under conditions with no gravity and no friction. In this study, a method of force-free control is proposed for industrial articulated robot arms. The force-free control proposed was applied to the direct teaching of industrial articulated robot arms in that the robot arm was moved by direct human force. Generally, the teaching of industrial articulated robot arms is carried out using operational equipment called a teach-pendant. Smooth teaching can be achieved if direct teaching is applicable. The force-free control proposed enables humans to teach industrial articulated robot arms directly. The effectiveness of force-free control was confirmed by experimental work on an articulated robot arm with two degrees of freedom.

多関節ロボットアームのトルクと速度制限下での許容軌跡内の高精度制御法

High speed and high accurate control performance is required for industrial robot arms. The research is aimed at high accurate control of industrial articulated robot arms with trajectory allowance under torque and speed constraints. The proposed method is based on nonlinear separation that decomposes the nonlinear dynamics from the nonlinear static parts and linear dynamic part. Controller was constructed for separation of trajectory generation and taught data generation, and it could be achieved perfect performance under the speed and torque constraints imposed by the hardware of robot arm. The eectiv eness of the proposed method was assured by experimental results of an actual articulated robot arm.

多関節ロボットアームの主軸と従軸のダイナミクス遅れ補償を施した主軸位置同期輪郭制御

多関節ロボットアームの主軸と従軸のダイナミクス遅れ補償を施した主軸位置同期輪郭制御

産業用多関節ロボットアームに対するカセンサレスのフォースフリー制御

This paper realized forcefree control of industrial articulated robot arm without external addition of force sensors. The forcefree control enables a motion of the industrial articulated robot arm as if it were in circumstance of non-gravity and non-friction condition. External force is detected by a torque monitor which is usually used in the servo controller of the industrial robot arm. The effectiveness of the proposed force sensor-less forcefree control was assured by simulation and experimental results of an actual industrial robot arm.

多関節ロボットアームの非線形分離型主軸位置同期輪郭制御法

多関節ロボットアームの非線形分離型主軸位置同期輪郭制御法

多関節ロボットアームの輪郭制御誤差の解析と動作条件の決定

Mechanism of locus error for contour following control of industrial articulated robot arms was analyzed and the locus error was derived theoretically. Main causes of locus error were found in the nonlinear transformation between kinematics and the inverse kinematics, and the delay of dynamics. The derived equation of the locus error was assured by simulation and experimental studies. Besides, the relationship between locus error and objective velocity was obtained by using the analyzed equation. As a result, objective velocity can be decided based on the maximum locus error and position loop gain of the servo controller. Moreover, optimal ratio of length of links was obtained by use of the derived relationship.

産業用多関節ロボットアームのトルク制限内の軌跡を重視した最短時間位置決め制御法

A positioning control of the industrial robot arms requires a performance of a high speed and a high accuracy. However, torque saturation existing in the industrial robot arms often causes deterioration of the positioning control performance. A method of trajectory generation and modifying the taught data in the joint coordinates was developed for the high speed positioning control of articulated robot arms by taking into account of the torque constraint. The effectiveness of the proposed method was assured by simulation studies and experimental results of an actual articulated robot arm. This method can be applicable not only to two axes robot arms, but also to the general articulated robot arms. As the proposed method does not require any change of the hardware of the robot arms, implementation of the proposed positioning control for the existing industrial articulated robot arms is easy and effective.

産業用多関節ロボットアームのトルク制限を考慮した輪郭制御性能の限界とその実現法

産業用多関節ロボットアームのトルク制限を考慮した輪郭制御性能の限界とその実現法

Propriety of Linear Model of Servo System for Industrial Articulated Robot Arms and Evaluation of Its Linearization Error

In this paper, propriety of the linearized servo system model for an industrial articulated robot arm was discussed. Industrially, the contour control of the robot arm has been implemented in such a way that an objective trajectory of the robot arm is divided into small segments and actuators of the servo motors have been controlled to pursue the divided segments, sequentially. In the conventional controller, the model of the robot arm control system has been regarded as the linear dynamic model in working coordinates. We consider this problem and analyzed the error of the linearized model. Based on the error analysis, we derive the permissible working region where the linearization error is negligibly small. In the permissible region, the robot arm dynamics can be expressed by a linear dynamic model in working coordinates.