Name: operation of the collaborative composite manufacturing (ccm) system
Uploaded: 2019-10-01T13:00:00
Description: Watch this Scientific Journal Video about Operation of the Collaborative Composite Manufacturing CCM System at JoVE.com

This project was funded by the Natural Sciences and Engineering Research Council (NSERC) of Canada Industrial Research Chair in Automated Composites Manufacturing and the Fonds de recherche du Qu&#233;bec &#8211; Natrue et technologies (FRQNT).

1. Frame Definitions of the CCM system
NOTE: The optical CMM is a dual camera sensor, which can track the object with a rigid set of reflectors as the targets in real time. The placement principle of these targets is that the targets are stuck at the asymmetric locations with certain distance among them. The targets need to be fixed on the robots or the placement head and remain in the field of view (FOV) of the optical CMM. At least four targets should be observed for each defined frame by the ...

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The experimental results show the manufacturing process of 90&#176; ply placement angles of the designed CCM system. The methodologies proposed in this paper can be used to lay up the fiber with 0&#176; and 45&#176; ply placement angles on the mandrel with Y-Shape and other shapes. While the built-in controller of the serial robot is able to provide the singularity avoidance feature17, only linear movement of the end-effector is supported. When the end-effector executes the task of the circle move...

Recently, the increasing need for high performance composite structures in various industries has greatly driven the development of the composite manufacturing technologies1,2. The traditional manual production cannot meet the high efficiency, accuracy and quality requirement of emerging industry. This aspect has encouraged the development of new production technologies such as AFP systems. The AFP technology automates the production of composite material structures using prepregs, which are present in the form of strips composed of impregnated fiber tapes (glass, carbon, etc.) of semi-polymerized resin. In the AFP system, a deposition head with the ability of heating and compacting the resin prepregs is mounted on a fiber placement machine or an industrial robot. The fiber placement machine or robot carrying the deposition head lays up the prepregs traversing the surface of the tooling mandrels. In the process of manufacturing, the tooling mandrel is used as a mold to be wound around by the prepregs to form a certain structure of composite part. The mandrel will be removed after the part is cured. The current AFP systems can significantly improve the efficiency and quality of the production of composite materials3,4,5. However, they are limited to the production of the open surfaces presenting a flat or contoured surface, or simple revolution parts such as cylinders or cones due to the insufficient DoF of the system and the difficulties in generating trajectories. Especially, the aerospace industry and the production industries of sports equipment are now interested in this technique for the production of structures with more complex geometries, like &#34;Y&#34; tubes or the structures forming closed-loops such as bicycle frames.
To be able to manufacture the structures with complex geometries, the flexibility of the AFP system should be improved. For example, an 8 DoF AFP system has been proposed6 by adding a linear track to a 6 DoF industrial robot and a rotational stage to the mandrel holding platform. However, the system is still not suitable for manufacturing the above-mentioned parts with complex geometries. The collaborative robotic system consisting of two robots is a promising solution to increase the dexterity by employing one robot to hold the fiber placement head at the end-effector and another robot to hold the mandrel. The two-serial-robot collaborative system may not solve the fiber placement problem, since the serial robots tend to deform and lose the accuracy due to its cantilever structure, considering the weight of the mandrel and the compaction force7. Compared with the serial robots, 6 DoF parallel robots, which have been utilized in the flight simulator and medical tools, enjoy better stiffness and accuracy8. Therefore, a parallel-serial collaborative robot system, in additional to a rotational stage mounted on the platform of the parallel robot, is built for handling the complex structures manufacturing in this paper.
However, the built collaborative robotic system yields difficulties in designing the controller for each robot to meet the high accuracy requirement of fiber placement. The accurate position measurement of the end-effector could be achieved by using laser tracking system, which is commonly used to guide the industrial robot in various aerospace drilling applications9,10. Although the laser tracking system can provide high accurate position measurement, the main drawbacks lie in the cost of the system and the occlusion issue. The laser tracking system is expensive, e.g., a commercial laser tracker and its accessories cost up to US$90,000, and the laser beam is easily occluded during the movement of the robots. Another promising solution is the vision measurement system, which can provide 6D pose measurement of the end-effector with a considerable accuracy at a low cost. The pose is referred to as the combination of the 3D position and 3D orientation of the end-effector with respect to the base frame of the robot. The optical CMM (see Table of Materials) is a dual camera-based visual sensor. By observing several reflector targets attached on the end-effectors of the two robots, the relative poses between the robots can be measured in real time. The optical CMM has been successfully applied to the robotic calibration11 and dynamic path tracking12 and thus is introduced to provide the feedback measurement to the closed-loop control systems of the proposed CCM system in this study.
The quality of the end composite product is largely dependent on how the original fiber path is generated for the AFP13,14. The path generation process is normally performed by using off-line programming software. The generated path consists of a series of tag points on the mandrel, which indicate the pose of the fiber placement head. Unlike other trajectory planning applications such as paint deposition, polishing or machining, where different types of coverage paths are possible, the choice is limited in the case of AFP, since the fiber is continuous and it is not possible to perform abrupt changes in direction (sharp corners) without damaging it and the placement head should be kept in the norm of the surface of the parts. The first development of trajectory generation technique for AFP has been concentrated on manufacturing large flat panels5 before moving towards the manufacturing the objects of 3D shapes such as open curved surfaces or cones5,14. But, no practical methodology has been developed for generating off-line path for the parts with complex geometries such as Y-shape or the other shapes. Therefore, an effective path planning algorithm for the parts with complex-contoured surfaces is designed to ensure uniform lay-up of subsequent fibers without gaps or overlaps in our previous research15. Considering the practicality and the effectiveness of the path generating algorithm, only the 6-DoF serial robot with the placement head and 1-DoF rotational stage as the mandrel holder are considered as the target system to find the optimum trajectory planning in joint space with minimum time criteria. It could be too complicated and time-consuming to generate the off-line trajectory for the whole 13 DoF CCM system due to the heavy kinematics calculation and the consideration of various constraints like singularities, collisions, smooth direction changing and keeping the placement head in the norm of the parts surface, etc.
The proposed off-line trajectory planning can generate the servo reference for the 6 DoF serial robot and the rotational stage respectively with exact timing. Even with this off-line trajectory planning, it could be impossible to generate a feasible path under all the constraints for certain geometry parts. Moreover, the positioning errors of the robots may cause the robots to collide with the mandrel or another device in the working environment. The on-line path modification is implemented based on the visual feedback from the optical CMM. Therefore the on-line pose correction algorithm is proposed to correct the path of the parallel robot and to tune a corresponding offset on the path of the serial robot simultaneously through the visual feedback. When the collision and other constraints are detected, the relative pose between the two robots is also kept unchanged while following the off-line generated path. Through the correction of the on-line path, the CCM system can avoid these points smoothly without any termination. Due to the flexibility of the parallel robot, the 6D correction offsets can be generated with respect to different constraints. This manuscript presents a detailed operation procedure of the CCM system using on-line pose correction algorithm.

<table>
	<tbody>
		<tr>
			<td>AeroBasic</td>
			<td>Aerotech</td>
			<td></td>
			<td>Motion control software</td>
		</tr>
		<tr>
			<td>Collaborative Composite Manufacturing (CCM) System</td>
			<td>Concordia University</td>
			<td></td>
			<td>A CCM system is proposed to manufacture more complex composite components which pose high demand for trajectory planning than those by the current AFP system. The system consists of a 6 degree-of-freedom (DOF) serial robot holding the fiber placement head, a 6-DOF revolute-spherical-spherical (RSS) parallel robot on which a 1-DOF mandrel holder is installed and an eye-to-hand optical CMM sensor, i.e. C-track, to detect the poses of both end-effectors of parallel robot and serial robot.</td>
		</tr>
		<tr>
			<td>C-track</td>
			<td>Creaform Inc.</td>
			<td></td>
			<td>An eye-to-hand optical CMM sensor</td>
		</tr>
		<tr>
			<td>Fanuc M-20iA</td>
			<td>Fanuc Inc.</td>
			<td></td>
			<td>Serial robot</td>
		</tr>
		<tr>
			<td>Matlab</td>
			<td>MathWorks</td>
			<td></td>
			<td>A multi-paradigm numerical computing software</td>
		</tr>
		<tr>
			<td>Quanser</td>
			<td>Quanser Inc.</td>
			<td></td>
			<td>Providing the engineering lab equipments for teaching and research.</td>
		</tr>
		<tr>
			<td>VB</td>
			<td>Microsoft</td>
			<td></td>
			<td>Visual Basic</td>
		</tr>
		<tr>
			<td>Vxelements</td>
			<td>Creaform Inc.</td>
			<td></td>
			<td>Software for C-track</td>
		</tr>
	</tbody>
</table>

operation of the collaborative composite manufacturing (ccm) system

The automated tape placement and the automated fiber placement (AFP) machines provide a safer working environment and reduce the labor intensity of workers than the traditional manual fiber placement does. Thus, the production accuracy, repeatability and efficiency of composite manufacturing are significantly improved. However, the current AFP systems can only produce the composite components with large open surface or simple revolution parts, which cannot meet the growing interest in small complex or closed structures from industry.
In this research, by employing a 1-degree of freedom (DoF) rotational stage, a 6-RSS parallel robot, and a 6-DoF serial robot, the dexterity of the AFP system can be significantly improved for manufacturing complex composite parts. The rotational stage mounted on the parallel robot is utilized to hold the mandrel and the serial robot carries the placement head to mimic two human hands that have enough dexterity to lay the fiber to the mandrel with complex contour.
Although the CCM system increases the flexibility of composite manufacturing, it is quite time-consuming or even impossible to generate the feasible off-line path, which ensures uniform lay-up of subsequent fibers considering the constraints like singularities, collisions between the fiber placement head and mandrel, smooth fiber direction change and keeping the fiber placement head along the norm of the part&#39;s surface, etc. Moreover, due to the existing positioning error of the robots, the on-line path correction is needed. Therefore, the on-line pose correction algorithm is proposed to correct the paths of both parallel and serial robots, and to keep the relative path between the two robots unchanged through the visual feedback when the constraint or singularity problems in the off-line path planning occur. The experimental results demonstrate the designed CCM system can fulfill the movement needed for manufacturing a composite structure with Y-shape.

The experiment aims at demonstrating the process of realizing the motion of laying up the fiber on the Y-shape mandrel of the proposed CCM system. The process is carried out in three steps: path generation; trajectory decomposition; and singularity and constraint avoidance.
Path generation 
Normally, the standard orientation is used in industry to define the different plies of the laminate. In this paper, t...

Watch this Scientific Journal Video about Operation of the Collaborative Composite Manufacturing CCM System at JoVE.com

Operation of the Collaborative Composite Manufacturing CCM System

A collaborative composite manufacturing system is developed for robotic lay-up of composite laminates using the prepreg tape. The proposed system allows the production of composite laminates with high levels of geometrical complexity. The issues in the path planning, coordination of the robots and control are addressed in the proposed method.

Operation of the Collaborative Composite Manufacturing (CCM) System

The automated tape placement and the automated fiber placement (AFP) machines provide a safer working environment and reduce the labor intensity of ...

The current automated fiber place machines can only produce large, open-surface parts, which cannot meet the growing interest in small complex structures from industry. By employing a rotational stage, a parallel robot, and serial robots, the dexterity of a fiber placement machine can be significantly improved for manufacturing complex composite parts. Demonstrating the procedure will be Pengcheng Li, a PhD student from my lab.Begin by loading the frame definition file through the software of the optical CMM. Click Positioning and Detect targets, and select the targets that are attached on the motors of the parallel robot. Click Accept to use those targets as the positioning reference of the whole system, and, in the Entities list, click Base Frame, and select Make this reference frame the origin.To define the tracking model of the end-effector platform frame, select Tracking models, click Detect model, and select the targets fixed on the end-effector platform of the parallel robot. Click Accept, and click Tracking models. Select UpPlatform in the drop-down, and click Up Frame.Then click Apply and File, Export, and Tracking model, and enter a file name to save the tracking model. To define the tracking model of the tool frame, select Tracking models and Detect model, and select the targets fixed on the tool frame of the serial robot. Click Accept, and click the Tracking models and SerTool.Then, select SerToolFrame in the drop-down list, click Apply, save the defined tracking model. To prepare the rotational stage, load the integrated control interface programmed by event-driven programming language on computer A, and click Connect to connect the controller of the rotational stage. Click Enable to connect the motor of the rotational stage, and click Home to move the rotational stage to the home position.To prepare the serial robot, power on the serial robot controller, and click Connect on the integrated control interface to connect the robot server. To prepare the optical CMM, power on the optical CMM controller, and wait until the screen of the controller shows Ready. Click Connect on the integrated control interface to connect the optical CMM via the application programming interface, and import the models built in section one, which include the base model, the upper platform model, and the end-effector model of the serial robot.Click Add Sequence, and add the relative sequence between the models as necessary. Then click Start Tracking to track the pose of the models. To prepare the parallel robot, power on the parallel robot controller.Load the SerialPort_Receive program, and select Normal mode. Load the Para Remote Control program, and select External mode. Then click Incremental Build to connect to the target, and click Start Simulation of the two programs to initialize the controller of the parallel robot.To generate the offline path, load the path planning interface through the numerical computing software, and click Import STL to select the part file. Click Segmentation and Add Work Region, and select the region on the extraction of cylinders. Adjust the slider to 100%and click Extract Cylinders and Add Work Region to select the starting branch of the path.Click Generate Path, and select Constant Placement Angle in the popup window. Then set the desired placement angle to 90 degrees, and select the red dot. To display the generated path, in the Select a Path dropdown menu, select the path, then save the file.To initiate a trajectory decomposition, run the Methode Jacobienne function in the numerical computing software, and open the desired path file. Enter the desired path number. The first point of the trajectory will be calculated.Then select the configuration of interest for the manipulator to reach this pose. When the configuration is complete, a graph showing the evolution of the joint values will be displayed, and a file containing the trajectory for the serial robot and the rotational stage will be generated. To run an offline path without a path modification algorithm, press Select on the teach pendant, and select the name of the imported file.Press Enter to load the path file, and turn the switch of the robot controller to Auto mode. Turn the teach pendant On/Off switch to Off, and press Cycle Start on the controller of the serial robot to run the path. Then click Cooperative Move in the cooperative control panel.To run an offline path with the path modification algorithm, set the serial robot to run the path as just demonstrated, and click DPM Connect in the cooperative control panel to add the online path modification ability for the system. Then click Cooperative Move in the cooperative control panel. As demonstrated, the generated 90-degree ply can cover two branches without any interruption, and the overlaps and gaps between the tapes can be minimized.To cover branch C, branches B and C are considered to generate the second trajectory. Another 90-degree ply will then be generated to cover branches A and C.Here, the decomposing process of continuously wrapping two branches of the Y-shaped mandrel with a constant 90-degree placement angle is illustrated. The mandrel can be decomposed to the trajectory of the serial robot and the rotary movement of rotational stage with a constant 90-degree placement angle as illustrated.In this experiment, an offline planning path was generated for manufacturing the Y-shape composite part, in which joint wrist singularity occurs. These experimental results demonstrate that the proposed method can create a pose correction for the parallel robot and adjust the offline path of the serial robot based on the optical coordinate measuring machine feedback. In this way, the system can smoothly pass the singularity and lay up the fiber along the path without termination, confirming that the proposed CCM system can successfully accomplish the manufacturing process of the Y-shape structure.The most important thing to remember is to operate the subsystems in the correct sequence. This collaborative system has the potential to manufacture small composite components of complex geometry by cooperating six degree of freedom, serial and parallel robots, and the optical coordinate measurement machine.

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