9 research outputs found
Adaptive Finite-Time Model Estimation and Control for Manipulator Visual Servoing using Sliding Mode Control and Neural Networks
The image-based visual servoing without models of system is challenging since
it is hard to fetch an accurate estimation of hand-eye relationship via merely
visual measurement. Whereas, the accuracy of estimated hand-eye relationship
expressed in local linear format with Jacobian matrix is important to whole
system's performance. In this article, we proposed a finite-time controller as
well as a Jacobian matrix estimator in a combination of online and offline way.
The local linear formulation is formulated first. Then, we use a combination of
online and offline method to boost the estimation of the highly coupled and
nonlinear hand-eye relationship with data collected via depth camera. A neural
network (NN) is pre-trained to give a relative reasonable initial estimation of
Jacobian matrix. Then, an online updating method is carried out to modify the
offline trained NN for a more accurate estimation. Moreover, sliding mode
control algorithm is introduced to realize a finite-time controller. Compared
with previous methods, our algorithm possesses better convergence speed. The
proposed estimator possesses excellent performance in the accuracy of initial
estimation and powerful tracking capabilities for time-varying estimation for
Jacobian matrix compared with other data-driven estimators. The proposed scheme
acquires the combination of neural network and finite-time control effect which
drives a faster convergence speed compared with the exponentially converge
ones. Another main feature of our algorithm is that the state signals in system
is proved to be semi-global practical finite-time stable. Several experiments
are carried out to validate proposed algorithm's performance.Comment: 24 pages, 10 figure
A Novel Uncalibrated Visual Servoing Controller Baesd on Model-Free Adaptive Control Method with Neural Network
Nowadays, with the continuous expansion of application scenarios of robotic
arms, there are more and more scenarios where nonspecialist come into contact
with robotic arms. However, in terms of robotic arm visual servoing,
traditional Position-based Visual Servoing (PBVS) requires a lot of calibration
work, which is challenging for the nonspecialist to cope with. To cope with
this situation, Uncalibrated Image-Based Visual Servoing (UIBVS) frees people
from tedious calibration work. This work applied a model-free adaptive control
(MFAC) method which means that the parameters of controller are updated in real
time, bringing better ability of suppression changes of system and environment.
An artificial intelligent neural network is applied in designs of controller
and estimator for hand-eye relationship. The neural network is updated with the
knowledge of the system input and output information in MFAC method. Inspired
by "predictive model" and "receding-horizon" in Model Predictive Control (MPC)
method and introducing similar structures into our algorithm, we realizes the
uncalibrated visual servoing for both stationary targets and moving
trajectories. Simulated experiments with a robotic manipulator will be carried
out to validate the proposed algorithm.Comment: 16 pages, 8 figure
Charge-carrier balance for highly efficient inverted planar heterojunction perovskite solar cells
The charge-carrier balance strategy by interface engineering is employed to optimize the charge-carrier transport in inverted planar heterojunction perovskite solar cells. N,N-Dimethylformamide-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and poly(methyl methacrylate)-modified PCBM are utilized as the hole and electron selective contacts, respectively, leading to a high power conversion efficiency of 18.72%
Engineering of Electron-Selective Contact for Perovskite Solar Cells with Efficiency Exceeding 15%
The past 5 years have witnessed the rise of highly efficient organometal halide perovskite-based solar cells. In conventional perovskite solar cells, compact n-type metal oxide film is always required as a blocking layer on the transparent conducting oxide (TCO) substrate for efficient electron-selective contact. In this work, an interface engineering approach is demonstrated to avoid the deposition of compact n-type metal oxide blocking film. Alkali salt solution was used to modify the TCO surface to achieve the optimized interface energy level alignment, resulting in efficient electron-selective contact. A remarkable power conversion efficiency of 15.1% was achieved under AM 1.5G 100 mW·cm<sup>–2</sup> irradiation without the use of compact n-type metal oxide blocking layers
Charge-Carrier Balance for Highly Efficient Inverted Planar Heterojunction Perovskite Solar Cells
The charge-carrier balance strategy by interface engineering is employed to optimize the charge-carrier transport in inverted planar heterojunction perovskite solar cells. N,N-Dimethylformamide-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and poly(methyl methacrylate)-modified PCBM are utilized as the hole and electron selective contacts, respectively, leading to a high power conversion efficiency of 18.72%
Dual-Source Precursor Approach for Highly Efficient Inverted Planar Heterojunction Perovskite Solar Cells
The highest efficiencies reported for perovskite solar cells so far have been obtained mainly with methylammonium and formamidinium mixed cations. Currently, high-quality mixed-cation perovskite thin films are normally made by use of antisolvent protocols. However, the widely used “antisolvent”-assisted fabrication route suffers from challenges such as poor device reproducibility, toxic and hazardous organic solvent, and incompatibility with scalable fabrication process. Here, a simple dual-source precursor approach is developed to fabricate high-quality and mirror-like mixed-cation perovskite thin films without involving additional antisolvent process. By integrating the perovskite films into the planar heterojunction solar cells, a power conversion efficiency of 20.15% is achieved with negligible current density–voltage hysteresis. A stabilized power output approaching 20% is obtained at the maximum power point. These results shed light on fabricating highly efficient perovskite solar cells via a simple process, and pave the way for solar cell fabrication via scalable methods in the near future
Dual-Source Precursor Approach for Highly Efficient Inverted Planar Heterojunction Perovskite Solar Cells
The highest efficiencies reported for perovskite solar cells so far have been obtained mainly with methylammonium and formamidinium mixed cations. Currently, high-quality mixed-cation perovskite thin films are normally made by use of antisolvent protocols. However, the widely used “antisolvent”-assisted fabrication route suffers from challenges such as poor device reproducibility, toxic and hazardous organic solvent, and incompatibility with scalable fabrication process. Here, a simple dual-source precursor approach is developed to fabricate high-quality and mirror-like mixed-cation perovskite thin films without involving additional antisolvent process. By integrating the perovskite films into the planar heterojunction solar cells, a power conversion efficiency of 20.15% is achieved with negligible current density–voltage hysteresis. A stabilized power output approaching 20% is obtained at the maximum power point. These results shed light on fabricating highly efficient perovskite solar cells via a simple process, and pave the way for solar cell fabrication via scalable methods in the near future
Pinhole-Free Hybrid Perovskite Film with Arbitrarily-Shaped Micro-Patterns for Functional Optoelectronic Devices
In many optoelectronic
applications, patterning is required for
functional and/or aesthetic purposes. However, established photolithographic
technique cannot be applied directly to the hybrid perovskites, which
are considered as promising candidates for optoelectronic applications.
In this work, a wettability-assisted photolithography (WAP) process,
which employs photolithography and one-step solution process to deposit
hybrid perovskite, was developed for fabricating patterned hybrid
perovskite films. Uniform pinhole-free hybrid perovskite films with
sharp-edged micropatterns of any shapes can be constructed through
the WAP process. Semitransparent solar cells with an adjustable active
layer average visible transmittance of a wide range from 20.0% to
100% and regular solar cells based on patterned CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> perovskite films were fabricated to demonstrate
that the WAP process was compatible with the manufacturing process
of optoelectronic devices. With the widely equipped photolithographic
facilities in the modern semiconductor industry, we believe the WAP
process have a great potential in the industrial production of functionally
or aesthetically patterned hybrid perovskite devices