Automatic Drilling Research Articles

Accurate positioning of a drilling and riveting cell for aircraft assembly

Modern aircraft assembly demands assembly cells or machines with higher machining efficiency and accuracy. Thus, a dual-machine drilling and riveting cell is developed in this paper. We firstly discuss its physical design, as well as the automatic drilling and riveting process. With the automatic drilling and riveting cell, drilling and riveting production line of aircraft panels can be expected. The frame chain of the drilling and riveting cell is constructed to link the assembly cell to its task space, which is the kinematics base. System calibrations, including task space calibration, the sensor calibration of an orientation alignment unit, the floating calibration of the implicit hand-eye relationship, are explored. For high positioning accuracy, a multi-sensor servoing method is proposed for cell positioning. An orientation-based laser servoing strategy, which uses the feedback of the orientation errors measured by laser displacement sensors, is used to align drilling direction and camera shooting direction. Besides, A single-camera-based visual servoing is applied to align the tool center point (TCP) to reference holes, to obtain their coordinates for drilling position modification. Experiments of multi-sensor servoing for cell positioning are performed on an automatic drilling and riveting machine developed for the panel assembly of an aircraft in China. With the cell positioning method, the automatic drilling and riveting cell can approximately achieve an accuracy of 0.05 mm, which can adequately fulfill the requirement for the assembly of the aircraft.

Feed rate control in robotic bone drilling process.

The bone drilling process is characterised by various parameters, the most important of which are the feed rate (mm/s) and the drill speed (rpm). They highly reflect the final effects and results of the drilling process, such as mechanical and thermal damages of bone tissue and hole quality. During manual drilling, these parameters are controlled by the surgeon based on his practical skills. But automatic drilling can assure an optimal result of the manipulation where such parameters are under control. During bicortical automatic bone drilling such a process consists of several stages: searching the contact with the first cortex, cortex drilling and automatic stop; searching the contact with the second cortex, cortex drilling and automatic stop; drill bit extraction. This work presents a way to control the feed rate during different stages of the bone drilling process (an original feed rate control algorithm) using the orthopaedic drilling robot (ODRO). The feed rate control is based on a proposed algorithm created and realised by specific software. During bicortical bone drilling process the feed rate takes various values in any stage in the range 0.5-6 mm/s. These values depend on drill bit position and real time force sensor data. The novelty of this work is the synthesis of an original feed rate control algorithm to solve the main problems of bone drilling in orthopaedic surgery - minimisation the drilling time (the heat generation); eliminating of the drill bit slip at the first (near) cortex and the drill bit bending at the second (far) cortex; minimising the risk of micro cracks which causes Traumatic Osteonecrosis; improving hole quality of the drilled holes; eliminating of the drill bit slip and the drill bit bending at the second cortex; minimising the value of the second cortex drill bit penetration by bicortical bone drilling.

Design and analysis of gripper for automatic drilling machine

In order to improve the synchronicity of the gripper of automatic drilling rig, three kinds of clamping devices for automatic drilling rig were designed to overcome the problem of deviation between the clamping center of the clamping device and the rotary center of the power head. At the same time, the driving characteristics, structures and working principle of the three grippers were introduced. With the finite element analysis conducted on the main structure parts, the results showed that the structure design and the parameter selection of the synchronous clamping mechanism component could meet the application requirements and could provide the guarantee to the reliability of the clamping mechanism and the integral performances of the automatic drilling rig.

Research on Intelligent Control Algorithm for Automatic Drilling of Vehicle-mounted Rig

The adaptability of traditional PID, fuzzy PID and feedback linearization sliding mode variable structure control intelligent algorithm to automatic drilling is analyzed. The results show that the feedback linearization sliding mode variable structure control algorithm has more ideal response speed, control accuracy and robustness, which solves the nonlinear problem of the electro-hydraulic control system of the truck-mounted drilling rig and improves the tracking control accuracy of the system during automatic drilling.

Numerical and experimental investigation on the rivet head flushness in automatic countersunk riveting

Riveting is an important interference-fit joining technology, which has been widely applied in aircraft assembly and many manufacturing fields. The rivet head flushness is an import industrial standard for the quality evaluation of a riveted joint. It would influence the aerodynamic performance of aircraft if not carefully controlled. In this paper, a finite element model (FEM) of automatic countersunk riveting is established and the formation of rivet head flushness is studied by the simulation results. Then, based on the coordinated motion of the riveting bar and the anvil tool, several compensation strategies are proposed to reduce the rivet head flushness and ensure the riveting quality, in which the riveting bar and anvil tool feed with the same speed (RASS) strategy is considered as the most efficient one. Finally, riveting experiments are conducted on a dual-machine-based automatic drilling and riveting system. The experimental results indicate that the simulation result is accurate, and the RASS compensation strategy is applicable and effective. This paper studies the formation mechanism and compensation method of the rivet head flushness for the countersunk rivet and provides scientific guidance for the riveting process optimization in engineering applications.

Discussion on Technical Problems and Development Suggestions of Engineering Drilling Rig Automation

<p>As one of the important technologies in the mining industry, the drilling machine technology can improve the efficiency and quality of the mining industry. Compared with the traditional drilling machine technology, the drilling machine automation technology is obviously more reliable. Drilling automation technology can not only optimize the traditional mining efficiency, but also ensure the safety of people in the mining process. At present, the automatic drilling machine is the highest level of drilling technology in China. In the process of the automatic drilling machine, the downhole closed-loop technology can be used. This technology can completely separate from the human control and automatically complete the task only by transferring the information to the underground central computer.</p>

Modeling and Optimization of Bidirectional Clamping Forces in Drilling of Stacked Aluminum Alloy Plates.

Interlayer burrs formation during drilling of stacked plates is a common problem in the field of aircraft assembly. Burrs elimination requires extra deburring operations which is time-consuming and costly. An effective way to inhibit interlayer burrs is to reduce the interlayer gap by preloading clamping force. In this paper, based on the theory of plates and shells, a mathematical model of interlayer gap with bidirectional clamping forces was established. The relationship between the upper and lower clamping forces was investigated when the interlayer gap reaches zero. The optimization of the bidirectional clamping forces was performed to reduce the degree and non-uniformity of the deflections of the stacked plates. Then, the finite element simulation was conducted to verify the mathematical model. Finally, drilling experiments were carried out on 2024-T3 aluminum alloy stacked plates based on the dual-machine-based automatic drilling and riveting system. The experimental results show that the optimized bidirectional clamping forces can significantly reduce the burr heights. The work in this paper enables us to understand the effect of bidirectional clamping forces on the interlayer gap and paves the way for the practical application.

Fully Automatic Robot-Assisted Surgery for Mandibular Angle Split Osteotomy.

With the development of computer-assisted surgery, preoperational design is detailed in software. However, it is still a challenge for surgeons to realize the surgical plan in the craniofacial surgery. Robot-assisted surgery has advantages of high accuracy and stability. It is suitable for the high-stress procedures like drilling, milling, and cutting. This study aims to verify the feasibility for automatic drilling without soft tissues in model test based on an industrial robot platform.This study chose the data from digital laboratory in Shanghai 9th People's Hospital. The mandibular was reconstructed in software and surgical plan was also designed. Then, the coordinate data was input to the robot's software and matrix conversion was calculated by 4 marked points. The trajectory generation was calculated by inverse kinematics for target coordinates and robot coordinates. The model was fixed and calibrated for automatic drilling. At last, the accuracy was calculated by optic scanning instrument.The installment and preparation cost 10 minutes, the drilling procedure cost 12 minutes. The outside position error was (1.71 ± 0.16) mm, the inside position error was (1.37 ± 0.28) mm, the orientation error was (3.04 ± 1.02)°. Additionally, a total of 5 beagles were tested, with an accuracy error of (2.78 ± 1.52) mm. No postoperative complications occurred.This is the first study reported for robot-assisted automatic surgery in craniofacial surgery. The result shows it is possible to realize the automatic drilling procedure under the condition of no interference like soft tissues. With the development of artificial intelligence and machine vision, robot-assisted surgery may help surgeons to fulfill more automatic procedures for craniofacial surgery.

Hybrid Visual Servoing for Rivet-in-hole Insertion Based on Super-twisting Sliding Mode Control

Aiming at solving the rivet-in-hole insertion problem of the complement riveting process, a novel hybrid visual servoing controller is proposed for an automatic drilling and riveting system, in which, combination of visual and laser sensor feedback is adopted to determine the relative pose errors of the rivet with respect to the hole. To compensate the system uncertainties, a super-twisting sliding mode controller (STSMC) is designed to provide continuous control inputs, and the end-effector can move to the desired pose by exponentially decreasing the feature errors. The proposed control scheme not only guarantees the stability of the control system but also provides a robust and quick rivet spot-positioning in the presence of manipulator errors and external disturbances of the riveting system. Finally, rivet-in-hole insertion experiments were conducted, the results show that accurate positioning can be achieved within a finite time (1~5s) which meets the demand of high-efficiency and flexibility in the riveting process since it can achieve global convergence from any initial camera pose as long as the hole is in the field-of-view (FOV) and the laser displacement sensors are in the working range at the beginning.

Research progress and perspective trend of drilling technology for carbon fiber reinforced polymer

Carbon fiber reinforced polymer (CFRP) has been widely used in the aviation, space and automobile structural parts manufacturing due to its excellent physical and mechanical properties. However, the properties of CFRP materials with inhomogeneity and anisotropy are vastly different from metals. In the process of drilling, it is easy to produce delamination, tearing, burr and other defects, which seriously affect the quality of drilling. Therefore, drilling technology of CFRP-metal stacks has become a difficult problem in aircraft assembly process. This paper summarizes the researches of drilling mechanism of CFRP in recent years. The relationship between chip formation mechanism and fiber orientation angle is generalized. Meanwhile, the relationship between axial drilling force, drilling temperature and tool shape, workpiece material, process parameters is summarized. The causes, detection, evaluation methods and restraining measures of typical machining damage during CFRP drilling processes, such as delamination, burr and tearing are analyzed. The latest advances in material, geometric structure of CFRP drilling tools, and development of simulation technology of CFRP drilling process are expounded. It is also proposed that the establishment of accurate and reliable constitutive model is the key to the research of drilling simulation technology. The development trend of CFRP drilling technology is prospected by introducing new CFRP drilling technologies, such as variable process parameters drilling, robotic automatic drilling and suction-type internal chip removal drilling.

Detection of Tool Wear in Drilling CFRP/TC4 Stacks by Acoustic Emission

Composite stacked material is widely used in many fields, such as aircraft, rocket, missile, and soon. In the process of drilling carbon fiber-reinforced polymer and titanium alloy lamination materials (CFRP/TC4, which is a typical structure in aircraft), tool wear is quick and serious, because the machining condition of the respective layers in stack is different. To ensure the drilling quality, drilling tool needs to be changed frequently. Therefore, if there is a detecting system in automatic drilling device to monitor and predict the tool wear effectively, it will help to improve the production efficiency and reduce the tool cost. Based on the experiments of drilling CFRP/TC4 stacks, the acoustic emission (AE) signals were carefully analyzed using the method of statistical analysis, spectrum analysis, and wavelet packet. The results show that the root-mean-square value of the AE signals and the energy of the wavelet packet are correlated with the tool wear. Meanwhile, experiments indicate that chips and tool fracture will cause instantaneous signal mutation, which may be appeared as disturbances. This has increased the difficulty of identifying the tool wear. With repeated experiments and comparison, it was found that the percentage of wavelet packet energy of some certain frequency sections increased with the tool wear, while some decreased. These variations will be possible to be used as features for further prediction in monitoring system.

Roughness of holes in metal and polymer composite bags

The article presents the results of the research on the influence of cutting modes on the parameters of surface roughness during finishing of holes in mixed packages containing composite and metal materials. The object of the study is a mixed package containing layers of polymer composite material (CFRP), as well as layers of titanium and aluminum alloys. The main technological equipment used in the study is an automatic drilling machine. Cutting tool -carbide six-toothed reamer. For carrying out of researches ranges of variation of modes of cutting have been chosen and the plan of experiment by means of software Statistica 6 is made. Two factors are considered under the plan of experiment: speed of cutting and delivery, the parameter of the allowance on expansion is introduced as the block factor. The models of multifactor dispersion analysis, which determine the influence of modes on the roughness of holes, were obtained empirically. Optimization of cutting modes has been carried out, the surface of desirability has been constructed, and recommendations on the choice of technological parameters of the process have been given.

Design of DOB-based riveting force controller for dual-machine horizontal drilling and riveting system

A dual-machine horizontal automatic drilling and riveting system for aircraft panel assembly is presented in this paper. Two cooperative machines are adopted, like a two-robot system, to achieve the unobstructed workspace, so it can be applied in an efficient assembly line. Different from the current deign wisdom to ensuring the riveting accuracy by increasing the machine stiffness, which detrimentally results in higher masses to be moved and sophisticated reinforcements being used, this paper proposes a disturbance observer (DOB) based design method of riveting force controller for adaptive riveting with high accuracy driven heads, reducing the dependence of automatic riveting on high stiffness of machine. This method simplifies the force-induced deformation error compensation problem to a force control problem, which has rarely been studied before in literature. The separate layout leads to weak machine stiffness in the whole workspace and the stiffness varies with machine pose greatly, which makes it difficult to establish an accurate force-induced deformation error compensation model. To make the riveting machine precisely generate the desired force under such stiffness-varying conditions, a robust control algorithm is designed: the disturbance observer is introduced to address the robust stability against model parameter variance caused by the change of system stiffness with pose, and the feedforward controller can achieve the high-bandwidth force control to ensure the riveting efficiency. The model identification experiments are carried out for different machine stiffness. Validation riveting experiments have been conducted to verify the proposed controller on the dual-machine riveting system. The results show that, compared with previous displacement control, the proposed force controller can ensure the consistency of driven heads through accurate force control.

Determination of the Optimal Path of Three Axes Robot Using Genetic Algorithm

Drilling is a chip machining process widely used in manufacturing .The term drilling includes all methods for making cylindrical holes in a work piece with chip cutting tools. There are many applications where drilling is used, such as drilling holes in PCBs. Robotic systems are used today to perform the drilling process. A problem that affects the use of these systems is the drilling sequence, as there are usually a number of points to visit. The determination of the drilling sequence is similar to the problem of synchronization of movement and travel time. The main objective is to optimize the time and trajectory of the three axes robot equipped with an automatic drill that seeks the best performance. In this paper, we have built a genetic optimization and problem solving algorithms to shorten the machining time to drill a given group of holes and reduce machining costs in order to improve the efficiency of the machining process as well robotic machining with three axes without degradation of the precision of the movement. The results of the experiments show that the proposed approach is feasible and practical. It is particularly useful in planning and scheduling systems for real-time manufacturing processes.

S9B-06 SESSION 9B: FACE RESEARCH - PART II ROBOT ASSISTED SURGERY FOR MANDIBULAR ANGLE SPLIT OSTEOTOMY FULLY AUTOMATIC – A PRECLINICAL STUDY

Introduction: With the development of computer assisted surgery, the preoperational design is detailed in the software. However, it is still a challenge for surgeons to realize the surgical plan in the craniofacial surgery. Robot assisted surgery has advantages of high accuracy and stability. It is suitable for the high stress procedures like drilling, milling and cutting. This study aims to verify the feasibility for automatic drilling without soft tissues in model test based on an industrial robot platform. Methods: This study chose the data from digital laboratory in Shanghai 9th People’s Hospital. The mandibular was reconstructed in software and surgical plan was also designed. Then, the coordinate data was input to the robot’s software and matrix conversion was calculated by four marked points. The trajectory generation was calculated by inverse kinematics for target coordinates and robot coordinates. The model was fixed and calibrated for automatic drilling. At last, the accuracy was calculated by optic scanning instrument. Results: The installment and preparation cost 10 minutes, the drilling procedure cost 12 minutes. The outside position error was (1.71±0.16) mm, the inside position error was (1.37±0.28) mm, the orientation error was (3.04±1.02)° Conclusion: This is the first study reported for robot assisted automatic surgery in craniofacial surgery. The result shows it is possible to realize the automatic drilling procedure under the condition without interference like soft tissues. With the development of artificial intelligence and machine vision, robot assisted surgery may help surgeons to fulfill more automatic procedures for craniofacial surgery.

Discussion on the development of intelligent drilling technology and equipment for gas drainage

This paper deals about the application and development of gas drainage intelligent drilling technology and equipment from remote automatic drilling, ground controlled drilling, ground long distance automatic control drilling, downhole remote control drilling, sub-source, and sub-area independent unit management.The main direction of our research is to achive full automatic drilling, intelligent drilling and drilling robots that can realize gas drainage, and also to promote innovation and development of gas drainage intelligent drilling technology.

Sensor-Based Control Using an Image Point and Distance Features for Rivet-in-Hole Insertion

This paper addresses the problem of stabilizing the machine at a pose specified by a reference image and four laser sensor readings. The system configuration combining monocular vision and laser pointers is applied for pose estimation of the end-effector as well as providing the control objective. Specific features are selected to reflect the pose of the end-effector in Cartesian space, and an adaptive controller is designed to implement the alignment between the end-effector and a stationary object for further assembly. The complete control scheme is assessed through simulations and experiments conducted on an automatic drilling and riveting system, the results demonstrate that the assembly task can be accomplished accurately and efficiently even with coarsely calibrated camera and laser pointers. Furthermore, decoupled results can be gained thanks to the selected features.

Hole position quick modification method for automatic drilling and riveting system considering workpiece pose deviation

Workpiece pose deviation is inevitable during automatic drilling and riveting in aircraft assembly, and it either leads to increased time cost or decreased position accuracy with the present methods. This study aims to propose a quick modification method to modify the coordinates of assembly holes based on online detection of the position of pre-assembly holes considering the effect of abnormal data caused by workpiece pose deviation. In the case of hole-making in the double curvature skin region of three pre-assembly holes, the space transformation matrix is determined using the unit quaternion method in accordance with the on-line detection of the hole position coordinates. In the case of more than three assembly holes with abnormal data, a new modification method using a random sampling consistency RANSAC algorithm is used to optimize the spatial transformation matrix and eliminate the abnormal data effectively. This method has been integrated into automatic drilling and riveting systems. Numerical simulation and experiment tests were conducted, and the result comparison showed that the method has obvious positive effect dealing with the abnormal data considering component pose deviation, which proves the effectiveness of the method.

Kinematic calibration of bracket type parallel posture alignment mechanism considering the gravity effect

Purpose The purpose of this study is to improve the position and posture accuracy of posture alignment mechanism. The automatic drilling and riveting machine is an important equipment for aircraft assembly. The alignment accuracy of position and posture of the bracket type posture alignment mechanism has a great influence on the operation effect of the machine. Therefore, it is necessary to carry out the kinematic calibration. Design/methodology/approach Based on analysis of elastic deformation of the bracket and geometric errors of the posture alignment mechanism, an improved method of kinematic calibration was proposed. The position and posture errors of bracket caused by geometric errors were separated from those caused by gravity. The method of reduction of dimensions was applied to deal with the error coefficient matrix in error identification, and it did not change the coefficient of the error terms. The target position and its posture were corrected to improve the error compensation accuracy. Furthermore, numerical simulation and experimental verification were carried out. Findings The simulation and experimental results show that considering the influence of the elastic deformation of the bracket on the calibration effect, the error identification accuracy and compensation accuracy can be improved. The maximum value of position error is reduced from 5.33 mm to 1.60 × 10−1 mm and the maximum value of posture error is reduced from 1.07 × 10−3 rad to 6.02 × 10−4 rad, which is superior to the accuracy without considering the gravity factor. Originality/value This paper presents a calibration method considering the effects of geometric errors and gravity. By separating position and posture errors caused by different factors and correcting the target position and its posture, the results of the calibration method are greatly improved. The proposed method might be applied to any parallel mechanism based on the positioner.

End stiffness modeling for automatic horizontal dual-machine cooperative drilling and riveting system

Aircraft panel automatic drilling and riveting system is the key equipment to realize aircraft panel assembly with high efficiency and quality. In practical application, automatic drilling and riveting system should bear cyclic riveting force with large load, which means such systems must have enough stiffness to deal with this situation. The stiffness of each components in automatic drilling and riveting system reflects as the end stiffness finally; in the meanwhile, end stiffness and riveting ability of the system will be affected when the posture of the system changes. According to this situation, stiffness matrixes related to mechanics characteristic of motion axes, transmission parts, inner-side working head, and outer-side working head of automatic horizontal dual-machine cooperative drilling and riveting system are established, in which the Jacobi matrix method, point transformation matrix method, and finite element analysis are applied. Finally, the static end stiffness model is proposed based on multi-body small deflection theory. The end stiffness model has been validated through experimental measurement, and the stiffness relationship of dual-machine tool system was obtained, which applied important data for structure optimization and control system design.