Time-Optimum Trajectories for Robots With Multiple End-Effectors

2003 ◽  
Author(s):  
Martin Hosek
Keyword(s):  
Flat Panel Display ◽  
Maximum Throughput ◽  
Throughput Performance ◽  
Straight Line ◽  
Optimum Trajectories ◽  
Manufacturing Applications ◽  
S Curve ◽  
End Effectors ◽  
Automated Tools ◽  
Motion Profile

Aggressive throughput performance of automated tools for semiconductor and flat-panel-display manufacturing applications have led to development of substrate-handling robots with multiple end-effectors. For maximum throughput levels, a method for calculating a time-optimum substrate transfer trajectory without causing any of the substrates carried by the robot to slide, and without violating other prescribed constraints, is required. This paper presents an algorithm which provides the required functionality with desirable computational efficiency and reliability. The key idea is to identify the set of fundamental trajectory shapes which cover all possible combinations of constraints for a given category of moves, e.g., moves along a straight line or along a circular arc, decompose the fundamental shapes into segments where a single constraint is active, and determine the time-optimum motion profiles in the segments. The fundamental shapes for each of the categories are found as simplified versions of the generic shape which corresponds to the case when all of the constraints are active. Each of the shapes has a set of conditions associated with it to determine whether the shape can be used for a particular move. An example comparison of a motion profile generated based on pre-defined time-optimum shapes with a conventional s-curve trajectory demonstrates that the present algorithm produces substantially faster motion, resulting in an improved throughput performance of the robot.

Three-Degree-of-Freedom Parallel Robot Arm

2006 ◽  
Author(s):  
Martin Hosek ◽  
Michael Valasek ◽  
Jairo Moura
Keyword(s):  
Parallel Robot ◽  
Degree Of Freedom ◽  
Motion Path ◽  
Angular Orientation ◽  
Robot Arm ◽  
Flat Panel Display ◽  
End Effector ◽  
Cluster Tools ◽  
Manufacturing Applications ◽  
Three Degree Of Freedom

This paper presents single- and dual-end-effector configurations of a planar three-degree of freedom parallel robot arm designed for automated pick-place operations in vacuum cluster tools for semiconductor and flat-panel-display manufacturing applications. The basic single end-effector configuration of the arm consists of a pivoting base platform, two elbow platforms and a wrist platform, which are connected through two symmetric pairs of parallelogram mechanisms. The wrist platform carries an end-effector, the position and angular orientation of which can be controlled independently by three motors located at the base of the robot. The joints and links of the mechanism are arranged in a unique geometric configuration which provides a sufficient range of motion for typical vacuum cluster tools. The geometric properties of the mechanism are further optimized for a given motion path of the robot. In addition to the basic symmetric single end-effector configuration, an asymmetric costeffective version of the mechanism is derived, and two dual-end-effector alternatives for improved throughput performance are described. In contrast to prior attempts to control angular orientation of the end-effector(s) of the conventional arms employed currently in vacuum cluster tools, all of the motors that drive the arm can be located at the stationary base of the robot with no need for joint actuators carried by the arm or complicated belt arrangements running through the arm. As a result, the motors do not contribute to the mass and inertia properties of the moving parts of the arm, no power and signal wires through the arm are necessary, the reliability and maintenance aspects of operation are improved, and the level of undesirable particle generation is reduced. This is particularly beneficial for high-throughput applications in vacuum and particlesensitive environments.

A Generic Method to Generate AS-Curve Profile in Commercial Motion Controller

2017 ◽  
Author(s):  
Youdun Bai ◽  
Xin Chen ◽  
Zhijun Yang
Keyword(s):  
Motion Controller ◽  
Residual Vibration ◽  
Practical Applications ◽  
Analytic Polynomial ◽  
Acceleration And Deceleration ◽  
Special Knowledge ◽  
Curve Profile ◽  
S Curve ◽  
Motion Profile ◽  
Better Than

It is well believed that S-curve motion profiles are able to reduce residual vibration, and are widely applied in the motion control fields. Recently, a new asymmetric S-curve (AS-curve) motion profile, which is able to effectively adjust the acceleration and deceleration periods, is proposed to enhance the performance of S-curve motion profile, and proved to be better than the traditional symmetric S-curve in many cases. However, most commercial motion controllers do not support the AS-curve motion profiles inherently. Special knowledge or expensive advanced controlling systems, such as dSPACE system, are required to generate the AS-curve motion command, which limits the applications of the AS-curve motion profile in many practical applications. In this paper, a generic method based on the Position-Velocity-Time (PVT) mode move supported by most commercial motion controllers is proposed to generate exact AS-curve motion command in real machines. The analytic polynomial functions of AS-curve motion profile are also derived to simplify the further application, and the effectiveness of the proposed method is verified by numerical simulation.

scholarly journals Online-Offline Optimized Motion Profile for High-Dynamic Positioning of Ultraprecision Dual Stage

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Yang Liu ◽  
Yue Dong ◽  
Jiubin Tan
Keyword(s):  
Model Identification ◽  
Direct Drive ◽  
Motion Platform ◽  
Residual Vibration ◽  
Dual Stage ◽  
Stage System ◽  
Curve Profile ◽  
High Dynamic ◽  
S Curve ◽  
Motion Profile

The wafer stage in dual-stage lithographic system is an air-bearing servo motion platform requiring high positioning accuracy and high transient performance. However, the residual vibration, resulting from almost zero damping, high velocity, parallel decoupling structure, and direct drive, brings about unacceptable overshoot and settling time. To suppress these unfavorable elements in high dynamic motion, a novel motion profile planning method combined with input shaping is proposed in this paper. Firstly, a trajectory named all free S-curve (AFS-curve) is derived, which has less constraints and better performance than traditional S-curve profile. Then, AFS-curve combined with a zero vibration shaper (ZV) is developed to further suppress residual vibration. Due to the very complex parameter adjustment, the online tuning may cause system oscillation that leads to damage of the precision stage. This paper, furthermore, proposes an online-offline method to optimize the parameters in the motion profile. Online step is performed to collect input and output data. Offline step includes the system model identification based on I/O data and parameter self-learning based on particle swarm optimization (PSO). The simulation and experimental results indicate that the proposed method achieves significant reduction of the positioning time and the overshoot in the dual-stage system.

scholarly journals Study on Acc/Dec Algorithm Based on Piecewise Polynomial in CNC

2011 ◽  
Vol 2-3 ◽  
pp. 43-47 ◽  
Author(s):  
Guo Shun Ji ◽  
Zhi Ping Chen ◽  
Ju Yong Zhang ◽  
Wei Liu
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Polynomial Function ◽  
Tracking Accuracy ◽  
Feedrate Planning ◽  
Smooth Motion ◽  
Planning Algorithm ◽  
S Curve ◽  
The Stability ◽  
Motion Profile

In order to improve the stability of feed movement in high speed CNC system, the feedrate planning algorithm based on piece-wise polynomial function was proposed. The flexible transition of feedrate was realized through maintaining linear continuous jerk. The principle of the proposed algorithm was introduced and the method to generate smooth motion profile based on the proposed algorithm was presented. The rapidity, stability and tracking accuracy of the feedrate planning algorithm to linearity, S curve and the proposed one were analyzed. The proposed algorithm is simple and it can be applied in acceleration/deceleration before interpolation in high speed feed movement to improve the stability of it. The proposed algorithm was applied in multi-contour high speed processing and the result indicated that it could improve the stability of large-scale parts motion.

Tuning the S-curve motion profile in short distance case

2013 ◽  
Author(s):  
Chang-Wan Ha ◽  
Keun-Ho Rew ◽  
Kyung-Soo Kim ◽  
Soohyun Kim
Keyword(s):  
Short Distance ◽  
S Curve ◽  
Motion Profile

scholarly journals Power-efficient beam tracking during connected mode DRX in mmWave and sub-THz systems

2020 ◽  
Author(s):  
Syed Hashim Ali Shah ◽  
Sundar Aditya ◽  
Sundeep Rangan
Keyword(s):  
Power Consumption ◽  
Power Saving ◽  
Cellular Systems ◽  
System Level ◽  
Maximum Throughput ◽  
Throughput Performance ◽  
Digital Beamforming ◽  
Power Efficient ◽  
Reduce Power Consumption ◽  
Discontinuous Reception

Discontinuous reception (DRX), wherein a user equipment (UE) temporarily disables its receiver, is a critical power saving feature in modern cellular systems. DRX is likely to be aggressively used at mmWave and sub-THz frequencies due to the high front-end power consumption. A key challenge for DRX at these frequencies is blockage-induced link outages: A UE will likely need to track many directional links to ensure reliable multi-connectivity, thereby increasing the power consumption. In this paper, we explore reinforcement learning-based link tracking policies in connected mode DRX that reduce power consumption by tracking only a fraction of the available links, but without adversely affecting the outage and throughput performance. Through detailed, system level simulations at 28 GHz (5G) and 140 GHz (6G), we observe that even sub-optimal link tracking policies can achieve considerable power savings with relatively little degradation in outage and throughput performance, especially with digital beamforming at the UE. In particular, we show that it is feasible to reduce power consumption by 75% and still achieve up to 95% (80%) of the maximum throughput using digital beamforming at 28 GHz (140 GHz), subject to an outage probability of at most 1%.

Positioning Repeatability of Robotic Systems With Synchronous Belt Drives

2009 ◽  
Author(s):  
Martin Hosek ◽  
Jay Krishnasamy ◽  
Stuart Beale
Keyword(s):  
Semiconductor Manufacturing ◽  
Robotic Systems ◽  
Design Parameters ◽  
Belt Drive ◽  
Lump Parameter Model ◽  
Belt Drives ◽  
The Past ◽  
Robot Arms ◽  
Manufacturing Applications ◽  
End Effectors

Substrate-handling robots for pick-place operations in semiconductor manufacturing applications are subject to strict substrate placement repeatability specifications. It has been observed that the placement locations at a given workstation tend to exhibit distinct clusters, each of which can be associated with another workstation accessed by the robot in the past, resulting in an undesirable increase of the overall placement repeatability range. In the present paper, this memory-like repeatability phenomenon is studied, and attributed to multistage synchronous belt drives, which are utilized to transmit motion from centralized motors to individual links and end-effectors of the robot arms. The phenomenon is investigated experimentally, and simulated using a simplified lump-parameter model. The effects of selected belt drive design parameters are examined, and the results are utilized to improve the positioning repeatability performance of a typical substrate-handling robot.

scholarly journals A handy new design paradigm

2011 ◽  
Vol 2 (1) ◽  
pp. 59-64 ◽  
Author(s):  
B. Bergelin ◽  
B. Slaboch ◽  
J. Sun ◽  
P. A. Voglewede
Keyword(s):  
Degrees Of Freedom ◽  
International Workshop ◽  
Control Algorithms ◽  
Industrial Setting ◽  
Technological Advances ◽  
Design Paradigm ◽  
Biomimetic Approach ◽  
End Effectors ◽  
And Control ◽  
Motion Profile

Abstract. In light of technological advances, researchers have lost sight of robotic grippers/end effectors design intent. In a semi-structured environment the biomimetic approach is impractical due to the high complexity of the mechanism and control algorithms. Current industrial grippers are robust, but lack the flexibility that allows for in hand manipulation. The authors believe that underactuated grippers provide the best approach to allow for in hand manipulation along with being rugged enough for an industrial setting. Thinking of the robotic gripper and the robotic arm as one system (as opposed to two separate subsystems), one is capable of using the degrees of freedom of the robot in conjunction with that of the gripper to provide the desired motion profile without the complexity of running two subsystems. This paper will outline where recent grippers have failed and will introduce a new design paradigm for grippers along with several underactuated gripper ideas. This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.

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