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Introduction to Reverse Engineering
Published in Keith L. Richards, Design Engineer's Sourcebook, 2017
Laser trackers are instruments that accurately measure large objects by determining the positions of optical targets held against those objects. The accuracy of laser trackers is on the order of 0.025 mm over a distance of several meters. Some examples of laser tracker applications are to align aircraft wings during assembly, and to align and collimate machine tools.
Dimensional Metrology
Published in Richard Leach, Stuart T. Smith, Basics of Precision Engineering, 2017
Massimiliano Ferrucci, Han Haitjema, Richard Leach
Laser trackers (see Figure 5.27e) are used to measure relatively large objects by determining the positions of optical targets held against the object (Schmitt et al. 2016). Typical uncertainties with laser trackers are of the order of 0.025 mm over distances of several metres.
Flatness measurement of large flat with two-station laser trackers
Published in International Journal of Optomechatronics, 2018
Jie Li, Jie Yang, Shibin Wu, Xuedong Cao
A laser tracker is essentially a portable coordinate measuring machine (CMM), it measures spherical coordinates instead of Cartesian coordinates. The tracker utilizes a laser interferometer (IFM) and two encoders to track and measure the location of a sphere-mounted retro-reflector (SMR) as it moves through space[5,6]. A laser tracker has excellent accuracy for the line-of-sight distance, but the angular measurements are less accurate. (Table 1)[7–9].
A procedure for the stiffness identification of parallel robots under measurement limitations
Published in Mechanics Based Design of Structures and Machines, 2023
Rasool Bina, Ali Kamali E., Afshin Taghvaeipour, Alexandr Klimchik
In this paper, a procedure to evaluate the stiffness behavior of parallel robots under measurement limitations was developed. The procedure can be simply implemented on complex robots while it needs simple and cheap test instruments. In this regard, the stiffness model was first calculated via the Modified Matrix Structural Analysis (MMSA) method. Then, by resorting to the Schur complement of the Cartesian stiffness matrix, multiple objective functions were defined. Next, the number of parameters which are required to be identified was reduced via a step-by-step procedure, and then, the corresponding nonlinear identification problem was solved by means of a multi-objective Genetic Algorithm (GA) method. As a case study, the stiffness identification procedure was first virtually evaluated on a 3-DOF Delta parallel robot while a single force was applied on the EF at different robot configurations, and a component of the corresponding displacement along one of the coordinate axes was calculated. In this case, the stiffness indices of the robot while the EF is displaced on a trajectory were evaluated with the maximum error of 5.5%. Next, the identification procedure was applied on an available prototype of Delta parallel robot. In this case, the external load was applied by means of simple weights, and the normal component of the displacement of EF was measured via a unidirectional laser sensor. The experimental results proved that the obtained model on average describes 95% of compliance errors and for the worst case the error does not overcome 9.8%. The advantages of the proposed algorithm for the stiffness identification of parallel robots can be summarized as it follows,The cost of identification is significantly reduced, e.g. the OPTEX-CD22 laser sensor has a price of about $700. Meanwhile, the price of a Laser tracker device nowadays is about $40,000.It is possible to choose a suitable direction to apply force on the EF. With this selection, the force can be applied to the EF with a simple fixture. While in other similar studies, it was necessary to apply forces and moments in different directions on the EF, which increases the complexity of the force application conditions and errors.