We report on a high speed silicon-waveguide-integrated PIN Ge photodetector of 45 GHz bandwidth, and a high efficiency of 0.3 V·cm silicon optical modulator with a metal-oxide-semiconductor (MOS) junction by applying the low optical loss and high conductivity poly-silicon gate. These OE/EO devices enable low drive voltage of around 1V, which would contribute to a high density optical interposer of the future photonics-electronics convergence system.

We developed a new video coding model that combines block-based finite ridgelet transform with H.264/AVC. This model is based on H.264/AVC codec and a new video coding mode called the ridgelet mode is added to it in order to incorporate the directional transform feature. In the ridgelet mode, residuals of each block after intra or inter predictions are transformed into a prime-number-sized block by a scaling filter to fit the finite Radon transform. Then the finite Radon transform and the 1D DCT are applied to the block. The ridgelet mode can adapt to such texture regions that have strong correlation along a specific direction and it can enhance the coding efficiency of the H.264/AVC by its directional feature of the finite Radon transform. We implemented the ridgelet mode onto a H.264/AVC based video encoder. The experimental results show the potential of this method for higher compression efficiency.

We propose a new method for improving motion vector coding. The coding efficiency of the H.264/AVC standard is significantly degraded for video sequences that include irregular motions. The degradation is caused by the fact that the correlations among the motion vectors on adjacent blocks get to be small when motions are irregular. Our method solves this problem by two schemes. First, the predictive motion vector (PMV) is adaptively coded with additional bits based on the distribution pattern of reference vectors. Second, an appropriate code table for the motion vector difference (MVD) is adaptively selected out of a couple of tables defined in advance. These schemes enable the appropriate methodologies for the motion vector coding to be adaptively selected according to the motion vector diversity. Experimental results show the effectiveness and potentiality of our approach for high coding efficiency.

This paper proposes a new mechanism and control method of 4-leg-wheel hybrid locomotion. Many previous hybrid vehicles execute wheel-mode and leg-mode alternatively. However, to overcome higher obstacle with sufficient velocity, a wheel locomotion should continuously be executed. In this paper, suitable load distribution control is proposed considering a contact force to the ground and step edge, a wheel driving torque, and a friction coefficient of the wheel and terrain. In a proposed new leg-wheel hybrid mechanism, load distribution control is realized by a torque of twisting joint at the center of the body, and a forward/backward shift of the body. The validity of this control and mechanism is confirmed by some experiments, where vehicle can run over a 105 mm step by 90 mm radius wheels with a good continuous movement. With an adjustment control of the approach angle, a robot can also ride over a 230 mm step