Processing configuration off-line optimization for functionally redundant robotic drilling tasks

The use of industrial robots for welding automation is a major and expanding applications area. In a welding task, the robot should smoothly trace along the weldseam with appropriate tool poses. For welding a complex 3-D curve, a large number of points should be taught to make the weld path smooth. This is a very tedious job and is not an easy way to leach the robot. In this paper, the requirements of a CAD system to be used as a robotic off-line arc-welding programming system are discussed. An off-line programming system for such application was developed. The workpieces and the weldseam were represented by analytical geometries. The positions and orientations of the weldgun along the trajectory were analysed by the task requirement of the welding procedure and solved by differential geometry. Calibration process was discussed to ensure programs were properly executed. This system is especially useful for off-line programming for the welding of complex 3-D curves.

This paper describes a robotic bone drilling and screwing system for applications in orthopedic surgery. The goal is to realize two robot manipulators performing cooperative bone drilling. The proposed cooperative bone drilling system can be divided into hardware and software development. The hardware development section consists of two robot manipulator arms, which perform drilling and gripping of the bone, and operates using two joysticks. The software section assists the surgeon in visual and navigation control of those robot manipulators. Controller used in this system can be included in the hardware and software sections. Disturbance observer based position control was used in the robot manipulator maneuver and reposition controller (cooperative control) was used in cooperative drilling operation to maintain the alignment of the drill bit during drilling. A mathematical model for the control system was designed and a real environment mimicking simulation for bone drilling was designed. The result of the simulation shows that the cooperative robot system managed to perform cooperative drilling when misalignment occurs during bone drilling. The bone gripping robot managed to restore the drill bit to its ideal alignment in every event of misalignment in the drilling axis. Therefore this cooperative system has potential application in experimental orthopedic surgery.

Grinding/lapping process is the final process for mold manufacturing, and is the criteria to check the quality of molds. However, this process depends on manual operation due to its work characteristics, and becomes the bottleneck process in the whole mold manufacturing process. To reduce mold manufacturing lead time, and to improve its productivity, multi joint robot system is implemented to automate grinding/lapping process. Total 8-axis redundancy grinding/ lapping robot system is developed as automation system which consists of 6-axis multi joint robot, 1-axis straight line carriage, 1-axis index table for walk rotation. Especially, we developed simulator which enables virtual drive simulation using OLP (Off Ling Programming) by importing 3D mold design data. In this study, we analyzed position error by measuring drive position command value and actual site robot driven automatic teaching using laser tracker, to optimize OLP simulation's operation program for grinding/lapping robot system. Based on this error analysis data, it will be able to compensate position for 3D walk model in virtual environment.

PurposeThe purpose of this paper is to present a novel automatic planning and coordinated control method of redundant dual‐arm space robot for inner space‐station operation based on multiple sensors information by stages.Design/methodology/approachIn order to improve the coordinated control capability of dual‐arm robot system, a four‐layer hierarchical control structure is designed based on the theory of centralization and decentralization. At the high‐level planning of dual‐arm system, a task decomposition strategy based on task knowledge and a task allocation strategy in terms of the robotic capability are proposed, respectively. Moreover, a control method by stages based on the information of multiple sensors is introduced to object recognition, task planning, path planning and trajectory planning. Finally, a 3D simulation and experiment of screwing nut and bolt are implemented on a dual‐arm robot system, and the feasibility and applicability of this control strategy are verified.FindingsThe automatic planning can be accomplished by means of sensors information by stages, and by this method, the autonomy and intelligence of dual‐arm space robot system can be further improved.Practical implicationsA new automatic planning strategy integrated with multiple sensors information by stages is proposed, and can be implemented on a dual‐arm robot system for inner space‐station operations. This method specializes in heterogeneous dual‐arm robot system.Originality/valueA task decomposition strategy based on task knowledge and a task allocation strategy in terms of the robotic capability are proposed, respectively. Moreover, a control method by stages based on the information of multiple sensors is introduced to object recognition, task planning, path planning and trajectory planning of dual‐arm robot system.

In this paper, a model is presented which, based on a description of the shape of a welding seam (the gab size and bevel angles), can be used to select variables controlling the welding of a root-bead. The model can be used in an off-line programming system as well as in a geometry-sensor based control system.The model is a stationary model and it is established on an empirical basis. Tests indicate that the model can be used to select control variables for seams with root gabs between 2 and 5 mm. The allowed deviation from the nominal value of the gab is app. 0.5 mm.The model has been implemented in an off-line programming system generating robot programs for welding thick walled large diameter nozzles perpendicular onto pipes. Tests with this off-line programming system indicate that if the workpiece geometry is defined sufficient well, a satisfactory weld quality is obtained when executing the control variables computed by the model.

Multi-sensor measurement system for robotic drilling

Research on kinematics of robot with passive wrists in minimally invasive surgery not only makes surgeons get Cartesian control mode in open surgery, but also lays the foundation for further research on control algorithm and trajectory planning. Taking the laparoscopic robot developed by Harbin Institute of Technology as an example, kinematics of robot is researched under minimally invasive environment. The position of incision point is influenced by diaphragm thickness and breath of patient, so a method of calculating incision position is given, position kinematics is presented by geometry and vector algebra method, velocity kinematics is solved through constraint conditions under minimally invasive environment. In order to verify the validity of algorithms, a series of experiments including inserting motion and rotation motion are performed, and the results show the validity of kinematics algorithms.

In clinics, customized archwires are demanded for lingual orthodontic treatment. However, only very experienced orthodontists can handle the manual appliance preparation. This pattern not only occupies lots of the orthodontist's labor time, but also can not ensure the accuracy of the appliances. Therefore, a robotic system was developed for automatic and accurate orthodontic archwire bending in our study. First, a method for customized archwire parameterization was developed. Second, an adaptive sampling-based bending planner with collision checker in time-varying environment was designed. Finally, a bending control strategy was used to eliminate the springback effect of the archwires and bending point shift during the bending process. A self-developed simulation platform based on Robot Operating System with MoveIt was used for preliminary validation of the proposed method. Physical experiments for multi-functional orthodontic bends on the robotic system were conducted as well. The results have shown that the developed robotic system using the proposed planning and control method was able to accomplish the automatic and accurate orthodontic archwire bending.

This paper uses the continuation method as a guideline to address the trajectory planning problem in robotic systems. It is assumed that the robotic system can be represented by a control affine system with output. From the homotopy map a partial differential equation is derived involving the control system and its variational system, whose solution yields a 1-parameter family of control functions. This family contains a solution to the trajectory planning problem, corresponding to the parameter growing up to infinity. The approach developed in the paper is illustrated with a trajectory planning problem for the kinematics of the rolling ball.

This paper deals with trajectory planning and motion learning for a redundant manipulator. Recently, behavior engineering for robotic systems has been discussed as a new technological discipline. A robotic system requires the whole structure of intelligence, and acquires skill and knowledge through interaction with a dynamic environment. Consequently, the whole structure determines the potentiality of intelligence. This paper proposes a robotic system with structured intelligence. Based on perceptual information, a robot with structured intelligence makes decision and action from four levels in parallel. In addition, the robot generates its motion through interaction with the environment, and at the same time, gradually acquires its skill based on the generated motion. To acquire skill and motion, the robot requires internal and external evaluations at least. This paper applies a virus-evolutionary genetic algorithm for trajectory planning and applies neural network for motion learning. Furthermore, we discuss its effectiveness through computer simulation results.

In this paper, according to the wheeled mobile robot with three wheels, the motor driving system of robot is researched. Based on robot kinematics and dynamics, a motor driving system of wheeled mobile robot is designed and developed. The results of experiments show that the system is steady and reliable at work, and it is very useful in practice.

Path deviations caused by geometrical errors in machining equipment significantly affect the machining quality of optical components. To enhance the quality and efficiency of optical component processing, this paper presents a Chebyshev interpolated Levenberg-Marquardt algorithm (CILM) aimed at compensating for path deviations in a robotic smoothing system utilized for optical component processing. First, the positioning accuracy of the robotic smoothing system is measured using a laser tracker. Subsequently, an objective function is constructed based on robot kinematics and error models to optimize the geometric errors in the system. Then, the proposed method is adopted to identify the geometric parameters of the robotic smoothing system to compensate for the smoothing path deviations. The compensation results confirm the effectiveness of the proposed method in enhancing the absolute positioning accuracy of the robotic smoothing system. Additionally, experimental verification is conducted to validate the effectiveness of the proposed method in improving the surface quality of optical components through smoothing path compensation. The results of the three experiments indicate that the proposed CILM achieves optical components with peak-to-valley values 15.70%, 28.7%, and 4.01% lower than those obtained before compensation, along with root mean square of 33.67%, 21.57%, and 10.23% lower than before compensation values, respectively. Moreover, the power spectral density curves of CILM exhibit smoother characteristics in comparison to the curves before compensation.

Stiffness can be considered of primary importance in order to guarantee the successful use of any robotic system for a given task. Therefore, this paper proposes procedures for carrying out both numerical and experimental estimations of stiffness performance for multibody robotic systems. The numerical procedure is based on models with lumped parameters for deriving the Cartesian stiffness matrix. The experimental procedure for the evaluation stiffness performance is based on a new measuring system named as Milli-CATRASYS (Milli Cassino tracking system) and on a trilateration technique

The kinematic and dynamic analysis of the high-degree of freedom (dof) hybrid systems that using serial and parallel robots together on fixed or mobile platform such as legged robots and service robots, is a rather difficult and complex, time consuming problem and a topic of great interest for researchers. There are many educational and commercial toolboxes which analyze serial and parallel robots separately. With the toolbox developed here, high-dof serial, parallel and hybrid robotics systems used on both fixed and mobile platforms can be designed and studied easily. Forward and inverse kinematics, Jacobian matrix, singularities, trajectory planning, torques and forces in joint and operational space can be examined with different robot designs. Using the toolbox that proposed in this paper, robot designer, researchers, students and educators can easily develop their own robotics systems and visualize them in the virtual reality environment provided by MATLAB. Also, it helps understanding fundamentals of high-dof multi-body hybrid robotics systems through user friendly interactive simulation. The most of existing toolboxes in the literature allow only user to analyze the predefined robots in their library with limited interactive capabilities. In some of them, the user can define a new robot with limited dof. But, the user must already have a prior knowledge about designing process of robots. In the proposed toolbox, designing and defining any new robotics systems become very easy. What makes this toolbox unique compared with the existing toolboxes is that any type of robot structures with high dof can be developed, analyzed and studied in detail.

The authors previously (1996) proposed a new type of space robot system, consisting of a spacecraft and a robot attached through a tether to it. This system is called a robot system. In this paper, we clarify the characteristics of the tethered robot system, and especially focus on position control of the center of mass of the robot. Tether tension is used to control the position, taking into account the gravity gradient and the centrifugal force. The results from the trajectory planning procedure suggest that the shape of the path depends both on the direction to the destination point and the time to accomplish the mission, it does not depend on the distance. From the simulation results with feedforward control it is concluded that accurate path planning is possible only if the destination point is close to the initial point, or if the time to accomplish the mission is long enough.