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This paper proposes a novel cooperative system for an Unmanned Aerial Vehicle (UAV) and an Unmanned Ground Vehicle (UGV) which utilizes the UAV not only as a flying sensor but also as a tether attachment device. Two robots are connected with a tether, allowing the UAV to anchor the tether to a structure located at the top of a steep terrain, impossible to reach for UGVs. Thus, enhancing the poor traversability of the UGV by not only providing a wider range of scanning and mapping from the air, but also by allowing the UGV to climb steep terrains with the winding of the tether. In addition, we present an autonomous framework for the collaborative navigation and tether attachment in an unknown environment. The UAV employs visual inertial navigation with 3D voxel mapping and obstacle avoidance planning. The UGV makes use of the voxel map and generates an elevation map to execute path planning based on a traversability analysis. Furthermore, we compared the pros and cons of possible methods for the tether anchoring from multiple points of view. To increase the probability of successful anchoring, we evaluated the anchoring strategy with an experiment. Finally, the feasibility and capability of our proposed system were demonstrated by an autonomous mission experiment in the field with an obstacle and a cliff., 7 pages, 8 figures, accepted to 2019 International Conference on Robotics & Automation. Video: https://youtu.be/UzTT8Ckjz1M

Robots working in natural, urban, and industrial settings need to be able to navigate challenging environments. In this paper, we present a motion planner for the perceptive rough-terrain locomotion with quadrupedal robots. The planner finds safe footholds along with collision-free swing-leg motions by leveraging an acquired terrain map. To this end, we present a novel pose optimization approach that enables the robot to climb over significant obstacles. We experimentally validate our approach with the quadrupedal robot ANYmal by autonomously traversing obstacles such steps, inclines, and stairs. The locomotion planner re-plans the motion at every step to cope with disturbances and dynamic environments. The robot has no prior knowledge of the scene, and all mapping, state estimation, control, and planning is performed in real-time onboard the robot., 2018 IEEE International Conference on Robotics and Automation (ICRA), ISBN:978-1-5386-3081-5, ISBN:978-1-5386-3080-8, ISBN:978-1-5386-3082-2

This paper describes application of a complex band-pass (BP) AE DA modulator to I-Q signal generation for I-Q balance testing of communication IC as well as ATE system usage. First we explain that the complex BP AE DA modulator is superior to two real-BP AE DA modulators regarding to noise-shaping characteristics. Then we examine the characteristics of the complex BP AE DA modulator and its extension — a complex multi-BP modulator — as well as its newly derived Data Weighted Averaging (DWA) algorithm for its linearity enhancement. We also propose a digital self-calibration technique, and show their simulation results. Their combination is also investigated. We discuss application of our proposed techniques to IC testing.

This paper describes two linearity enhancement algorithms for I-Q signal generation using a multi-bit complex band-pass (BP) ΔΣ DA modulator targeted for communication IC design and testing applications. The first one is a complex multi-band-pass data-weighted-averaging algorithm and the second is a self-calibration algorithm. The generated I, Q signals can be up-converted to a high frequency signal. We present their principles and MATLAB simulation results.

We investigated an optical frequency comb generated by an InP-based semiconductor Mach-Zehnder (MZ) modulator by using a numerical model that takes into account the nonlinear change of a refractive index and an optical absorption induced by an applied voltage in the modulator. Such nonlinearities are negligible for conventional LiNbO3-based MZ modulators but not negligible for semiconductor MZ modulators. The numerical model quantitatively reproduced our experimental data reported previously. We found that the nonlinearities play an important role to obtain the flat 9-channel optical frequency comb block with an intensity deviation of less than 1 dB, when a moderate RF drive voltage of < 5 V was used. This result was sustained regardless of an RF drive voltage ratio between two arms in the MZ modulator.

A 7b 1.4 GS/s flash ADC is developed in 45 nm CMOS. This is the first paper of an ADC with offset drift suppression techniques for dynamic comparator and preamplifier. These techniques make the ADC robust against environmental variation. As a result, once the ADC is calibrated at power up, no more calibration is necessary even under VDD or temperature variations. The ADC occupies a small area of 0.085 mm2 and dissipates 33.24 mW at 1.4 GS/s from a 1.15V supply.

A 6-bit 3.5-GS/s flash ADC is reported. A load circuit with a clamp diode and a replica-biasing scheme is developed for low-voltage and high-speed operation. An acceleration capacitor is introduced for high-speed overdrive recovery of a comparator. An averaging and interpolation network is employed in this ADC. The interpolation factor is optimized considering random offset, active area, and systematic offset to realize low offset and small active area. The ADC is fabricated in a 90-nm CMOS process and occupies 0.15 mm2. It consumes 98 mW with a 0.9-V power supply. With Nyquist input, SNDR and SFDR at 3.5 GS/s are 31.18 dB and 38.67 dB, respectively.

We will report a novel batch transferred micromirror using flip-chip bonding and surface micromachining with large angle displacement. The micromirror system is fabricated through MUMPs (multi-user MEMS processes) and composed of a micromirror, electrodes, fuse-away tethers, and solder joints. Transfer is achieved using temporary fuse-away tethers that suspend the released micromirror. The tethers can be easily broken away when current for fusion is applied. The location alignment between the micromirror and the electrodes can be easily obtained due to solder self-aligned joints. The micromirrors and tethers are designed based on electrical-mechanical combined analyses and heat transfer simulations. In addition, design optimization is carried out to decrease the driving voltage. After the optimization, a large displacement angle of 5 degrees is achieved at a driving voltage of 70 volts.

This paper describes a single-chip Bluetooth transceiver LSI, which uses a standard 0.18 /spl mu/m bulk CMOS process. It can operate at a supply voltage of 1.8 V, and includes even a low loss transmit/receive antenna switch (SW) in order to realize high level integration. For lower chip area, a channel selection filter consists of simple linearized source-coupled pairs, and the transceiver occupies 10.2 mm/sup 2/.

A 10-b video CMOS D/A converter for low supply voltage has been developed. Nonsaturating transistors and a new switching scheme are introduced to current sources in the D/A converter, which operates at 50 MS/s with a 2.7 V power supply. Integral linearity error and differential linearity error are less than 0.5 LSB and 0.25 LSB, respectively. The dependence of the linearity error on full-scale voltage is plotted. Device characteristics are summarized. >

In consumer video-system markets, A/D converters (ADCs) are desired to be integrated with digital signal-processing circuitry to reduce system cost and size. Operation with low supply voltage (V/sub DD/) is also desired in personal equipment. In addition, circuit techniques for low-V/sub DD/ operation are essential for ADC integration into 0.5 /spl mu/m LSIs. The first low-V/sub DD/ 10b video ADC to be published uses CMOS inverters as amplifiers in "chopper" type comparators. However, experimental results show that this type of circuit has poor noise immunity when integrated into mixed-signal LSIs. A 10b 20 Ms/s CMOS ADC with 3 V power supply and high noise immunity for integration into mixed-signal LSIs is described by the authors. >

A single-chip RF transceiver LSI for 2.4 GHz-band GFSK applications uses a 0.5 /spl mu/m BiCMOS which provides 23 GHz f/sub T/. The transceiver consumes 34.4 mA in TX mode (PA, PLL) and 44.0 mA in RX mode (LNA, IR mixer, filters, limiter, RSSI, demodulator, PLL). It has a linear FV conversion demodulator with wide input-frequency range.