Improvement in the rate capability
needs to be addressed for utilization of a Si anode in high-power
Li-ion batteries. Regarding the rate capability, its improvement by
Si–C nanocomposites seems to be somewhat saturated, thus indicating
that the other method should be tried for further enhancement of the
rate capability. Here, we introduce Si nanoparticles uniformly coated
with nanometer-thick polyacrylonitrile (PAN) with better wettability
to liquid electrolytes and minimizing electronic resistance, which
might result from a thick PAN coating: the effective contact surface
area made by the contact of Si nanoparticles and liquid electrolyte
is increased for larger Li-ion current, leading to ultrafast rate
capability retaining 62% of the 0.2C rate discharge capacity at 100C.
In addition, a strong adhesive property of PAN provides highly mechanically
robust Si anodes for multielectrode-stacked flexible lithium-ion batteries,
which show no physical damage after 30 000 bending cycles with
a bending radius of 25 mm.
This article presents an inexpensive inertial attitude and position reference system for a small unmanned aerial vehicle (UAV) that utilizes low cost inertial sensors in conjunction with a global positioning system (GPS) sensor. The attitude estimates are obtained from a complementary filter and a Kalman filter by combining the measurements from the inertial sensors with the supplementary attitude information from GPS. A method is proposed to deal with the GPS data latency and momentary outages. The inertial position is estimated from a separate Kalman filter that is cascaded after the attitude filters in order to reduce the computational overhead. Numerical simulation results and hardware validation show that this is a simple, yet effective method for attitude and position estimation, suitable for real-time implementation on a small UAV.
This article presents the details of a newly constructed 3-dof experimental spacecraft simulator facility at the School of Aerospace Engineering at the Georgia Institute of Technology. The main component of the facility is a cylindrical platform located on a hemi-spherical air bearing that allows friction-free rotation about three axes. The facility includes a variety of actuators and sensors: gas thrusters, variable-speed controlled momentum gyros (which can operate solely in a reaction wheel (RW) or in a control momentum gyro (CMG) mode), a two-axial sun sensor, a high-precision three-axial rate gyro, a three-axial magnetometer, and a complementary inertial measurement unit. The facility offers a truly integrated attitude control system (IACS) for experimental testing of advanced attitude determination and control algorithms.
In this study we investigate the problem of generating a smooth, planar reference path, given a family of discrete optimal paths. In conjunction with a path representation by a finite sequence of square cells, the generated path is supposed to stay inside a feasible channel, while minimizing certain performance criteria. Constrained optimization problems are formulated subject to geometric (linear) constraints, as well as boundary conditions in order to generate a library of B-spline path templates. As an application to the vehicle motion planning, the path templates are incorporated to represent local segments of the entire path as geometrically smooth curves, which are then joined with one another to generate a reference path to be followed by a closed-loop tracking controller. The on-line path generation algorithm incorporates the path templates such that continuity and smoothness are preserved when switching from one template to another along the path. Combined with the D *-lite path planning algorithm, the proposed algorithm provides a complete solution to the obstacle-free path generation problem in a computationally efficient manner, suitable for real-time implementation.
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