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Frog-leg robots have been widely used for handling silicon wafers inside the vacuum environment of semiconductor manufacturing machines. In order to enhance stiffness, frog-leg robots adopt a parallel structure. A main challenge of controlling wafer handling robot is avoiding vibration, which is the major cause of wafer sliding and particle contami...
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... order to transfer wafers, the robot needs at least two degrees of freedom. Parallel structures with closed-chain mechanisms are favorable to give higher stiffness. In the past two decades, the frog-leg dual blade robots have become a very popular type for IC fabrication machines over the world. As shown in Fig. 1 Despite the closed-chain mechanism used to enhance stiffness [1], the links of the frog-leg robot are quite thin and introduce flexibility. In addition, the magnetic coupler used for separating the motors from the vacuum introduces not only compliance in torque transmission but also actuation-sensing mismatch problem. Without a ...
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... searching direction in the design space is needed in order to find the optimal point. The performance gradient estimation of the start point is thus necessary, as shown in Fig. 10. The steepest descent direction is then obtained as the opposite direction of the gradient. The points near the start point should be uniformly distributed to guarantee the estimation accuracy. Sobol sequence is used to distribute points around the start point, because it will produce more uniformly distribution than other methods. 20 ...
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... corresponding motor trajectories are determined using inverse kinematic model. Figure 12 shows the following errors, where jnt i stands for the i th joint (i=1,5), and act pos i, cmd pos i stand for the actual position, the command position of the i th joint. ...
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... search is to search the optimal point along the steepest descent direction in the design space, as shown in Fig. 11. The search path turns direction when it reaches a boundary, and terminates when it reaches a corner. The resulting search path is a polyline. The boundary of the design space is determined conservatively using classic linear analysis to guarantee ...
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... second extensional move is a no-wafer extension, which lasts a shorter time duration. Figure 13 shows the following errors. The improvement with torque feedforward is obvious. ...
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... improvement with torque feedforward is obvious. Figure 13. Result of feedforward control for second extension. ...
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... of feedforward control for second extension. Figure 14 shows the following errors of the rotational move. Comparing the performance of the two segments marked by dashed blocks, the large vibration at the beginning of the move is eliminated, which proves the effectiveness of using model based torque feedforward control. ...
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... results confirm the improvement brought by optimal gain tuning. Figure 15 shows the performance of the start point and the optimal point. The top plot in the figure shows the equivalent Cartesian space following errors calculated from the joint space errors, and the bottom plot shows the accelerations (not the acceleration error) measured at the wafer center. ...
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Citations
... Ito et al. [38] designed a feedback controller to achieve a closed-loop bandwidth of 260 Hz. Yu et al. [39] designed a controller and optimal tuning of a wafer handling robot. The control system can reduce the vibration to a certain extent, but it cannot solve the redundant vibration, and cannot isolate the vibration excitation of the multi-degree-of-freedom system. ...
The vibration problem influences the precision of the equipment. However, some vibration isolation systems (VISs) with the perfect theoretical and simulation results are still unable to suppress the vibration well, resulting in the damage during the operation, such as the phenomenon of fragments for the end effector of a glass substrate handling robot. Therefore, this paper focuses on the glass substrate handling robot in actual production and simplifies the VIS into a 2D (2 degree) system. From the analysis of the deviation of material parameters and installation deviations between vibration isolators, this paper concludes that, as long as there is a deviation, the vibration isolation performance of the system will be reduced. Through the mutually verified theory, simulation, and experimental structure, this paper also presents that the resonance frequency increase factor of the vibration isolation system is approximately the deviation. As for the end effector, the distance of the two vibration isolations is 579.4 mm. The change of the load does not change the isolation frequency of the same system, but the resonance amplitude will increase. The results of this study can supervise the installation and selection of vibration isolators in VISs. At the same time, the reasons for the weak vibration isolation performance of some systems are explained.
... However, complex computations can limit real-time performance, especially because all axes (shoulder, elbow, and wrist) move synchronously. Another type, a frog-leg robot [36], which has enhanced stiffness due to its parallel structure, could be used for handling silicon wafers inside the vacuum environment of semiconductor manufacturing machinery. The basic triloop PID (proportional-integral-derivative) feedback controller and torque offset estimated through the robot model are the inputs used to compensate for the system's nonlinear dynamics. ...
To face contemporary problems, international engineers must be trained in advanced learning environments and with professional skills and knowledge. Sponsored by USAID (US Agency for International Development), the Build-IT (Building University-Industry Learning and Development through Innovation and Technology) program leverages the vast capabilities of the implementing partner from Arizona State University and plays a key role as an innovative pioneer in converging personalities from various fields. A well-educated engineer can contribute to the sustainable development of society. With the aim of building community-oriented education, an integrated strategy was proposed in which a problem-based learning method is investigated to apply technical knowledge. In accordance with this strategy, in our proposed method, students from Mechatronics Engineering first had to work together with other learners in the electronics, software, control automation, and mechanics fields, followed by the design of an open platform integrated multi-disciplinary approach. By collaborating with their peers in developing this hardware, students become better equipped with specialized knowledge. This process also allows students to feel confident in implementing their innovative thinking while still maintaining the core meaning of the instrument. One of the key benefits of this approach is that helping students overcome their problems concurrently enhances the engineer’s function in the community despite missing some specialized skill sets. Based on experimental works using this open framework, the present approach demonstrates that pupils in our program have sufficient ability to contribute to social achievements. Lastly, the feasible, low-cost, and visually educational instrument made by the participants showcases the value of such a multi-disciplinary approach.
