1,273 research outputs found
Kinematic calibration of Orthoglide-type mechanisms from observation of parallel leg motions
The paper proposes a new calibration method for parallel manipulators that
allows efficient identification of the joint offsets using observations of the
manipulator leg parallelism with respect to the base surface. The method
employs a simple and low-cost measuring system, which evaluates deviation of
the leg location during motions that are assumed to preserve the leg
parallelism for the nominal values of the manipulator parameters. Using the
measured deviations, the developed algorithm estimates the joint offsets that
are treated as the most essential parameters to be identified. The validity of
the proposed calibration method and efficiency of the developed numerical
algorithms are confirmed by experimental results. The sensitivity of the
measurement methods and the calibration accuracy are also studied
Design and Development of 3-DOF Modular Micro Parallel Kinematic Manipulator
This paper presents the research and development of a 3-legged micro Parallel Kinematic Manipulator (PKM) for positioning in micro-machining and assembly operations. The structural characteristics associated with parallel manipulators are evaluated and the PKMs with translational and rotational movements are identified. Based on these identifications, a hybrid 3-UPU (Universal Joint-Prismatic Joint-Universal Joint) parallel manipulator is designed and fabricated. The principles of the operation and modeling of this micro PKM is largely similar to a normal size Stewart Platform (SP). A modular design methodology is introduced for the construction of this micro PKM. Calibration results of this hybrid 3-UPU PKM are discussed in this paper.Singapore-MIT Alliance (SMA
On the optimal design of parallel robots taking into account their deformations and natural frequencies
This paper discusses the utility of using simple stiffness and vibrations
models, based on the Jacobian matrix of a manipulator and only the rigidity of
the actuators, whenever its geometry is optimised. In many works, these
simplified models are used to propose optimal design of robots. However, the
elasticity of the drive system is often negligible in comparison with the
elasticity of the elements, especially in applications where high dynamic
performances are needed. Therefore, the use of such a simplified model may lead
to the creation of robots with long legs, which will be submitted to large
bending and twisting deformations. This paper presents an example of
manipulator for which it is preferable to use a complete stiffness or vibration
model to obtain the most suitable design and shows that the use of simplified
models can lead to mechanisms with poorer rigidity
An Overview of Kinematic and Calibration Models Using Internal/External Sensors or Constraints to Improve the Behavior of Spatial Parallel Mechanisms
This paper presents an overview of the literature on kinematic and calibration models of parallel mechanisms, the influence of sensors in the mechanism accuracy and parallel mechanisms used as sensors. The most relevant classifications to obtain and solve kinematic models and to identify geometric and non-geometric parameters in the calibration of parallel robots are discussed, examining the advantages and disadvantages of each method, presenting new trends and identifying unsolved problems. This overview tries to answer and show the solutions developed by the most up-to-date research to some of the most frequent questions that appear in the modelling of a parallel mechanism, such as how to measure, the number of sensors and necessary configurations, the type and influence of errors or the number of necessary parameters
Kinematic calibration of orthoglide-type mechanisms
The paper proposes a novel calibration approach for the Orthoglide-type
mechanisms based on observations of the manipulator leg parallelism during
mo-tions between the prespecified test postures. It employs a low-cost
measuring system composed of standard comparator indicators attached to the
universal magnetic stands. They are sequentially used for measuring the
deviation of the relevant leg location while the manipulator moves the TCP
along the Cartesian axes. Using the measured differences, the developed
algorithm estimates the joint offsets that are treated as the most essential
parameters to be adjusted. The sensitivity of the meas-urement methods and the
calibration accuracy are also studied. Experimental re-sults are presented that
demonstrate validity of the proposed calibration techniqu
Calibration of 3-d.o.f. Translational Parallel Manipulators Using Leg Observations
The paper proposes a novel approach for the geometrical model calibration of
quasi-isotropic parallel kinematic mechanisms of the Orthoglide family. It is
based on the observations of the manipulator leg parallelism during motions
between the specific test postures and employs a low-cost measuring system
composed of standard comparator indicators attached to the universal magnetic
stands. They are sequentially used for measuring the deviation of the relevant
leg location while the manipulator moves the TCP along the Cartesian axes.
Using the measured differences, the developed algorithm estimates the joint
offsets and the leg lengths that are treated as the most essential parameters.
Validity of the proposed calibration technique is confirmed by the experimental
results.Comment: ISBN: 978-3-902613-20-
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