Incremental analog-to-digital converters (IADCs) are well-suited for multiplexing across sensor nodes. Continuous-time (CT) implementations often offer better energy efficiency than switched-capacitor circuits. This paper presents a medium-bandwidth and high-resolution IADC incorporating a second-order CT loop filter and an entirely passive noise-shaping successive approximation-register (SAR) internal quantizer with a direct input feedforward path. The noise-shaping SAR quantizer enhances noise shaping by one additional order. Meanwhile, the direct input feedforward path mitigates the voltage ringing issues that arise when resetting the loop filter during incremental operation, thereby successfully extending the maximum stable amplitude. The proposed hardware prototype is fabricated in$0.18~\mu $m CMOS technology, occupying an active area of 0.38 mm2. It achieves a peak SNDR of 89.2 dB with an input amplitude of -2 dBFS and a DR of 91.9 dB for 100 kHz signal bandwidth. Operating at a 1.8V supply voltage, the prototype consumes 1.19 mW, resulting in a Schreier FoM of 168.4/171.1 dB.

In a single-flux-quantum (SFQ) circuit, almost all cells need to receive the clock signal which incurs a high clock routing overhead. Besides, the clock tree of an SFQ circuit requires the insertion of a clock splitter cell at every tree branching point which renders the conventional design flow of placement followed by clock tree synthesis ineffective to obtain a high quality clock tree with low clock skew. To address these issues, we propose a two-stage global placement methodology and a placement refinement algorithm after placement legalization. Our two-stage global placement methodology first applies a conventional global placement algorithm to place the cells in the given SFQ circuit evenly, which is followed by clock tree synthesis and clock splitter insertion, and then performs a second stage of global placement to re-place both the original cells and clock splitters at the same time. In the second global placement stage, the look-ahead legalization technique is used to spread out the original cells and the clock splitters, and the clock tree is re-synthesized several times to obtain an optimized clock tree topology such that there are little overlaps of the clock splitters with the original circuit cells. In addition, the total wirelength of data signals and clock signal is optimized concurrently. After legalizing the placement of all cells, our placement refinement method can be run to further reduce the clock skew. Compared with the previous state-of-the-art work, on average we can reduce the total half-perimeter wirelength and clock skew by 9% and 31%. respectively.

ABSTRACT Three‐party encrypted key exchange (3PEKE) enables two communicating parties to securely exchange confidential and authenticated information over an insecure network via a trusted server. This investigation presents a novel efficient and secure 3PEKE protocol using a super‐poly‐to‐one trapdoor function. The proposed protocol employs the Diffie–Hellman key exchange and adopts the technique that the clients can publicly exchange the factors for generating the session key without the help of the server to reduce the numbers of transmissions. A round‐efficient version of the proposed 3PEKE protocol is also described. Compared with related approaches, the proposed protocol not only retains security requirements and possesses lower computational cost but also has fewer transmissions and realizes the lower bounds of communications. Copyright © 2013 John Wiley & Sons, Ltd.

A vision sensor mounted on a robot to detect surrounding objects is discussed. Its mounting position and orientation must be identified, resulting in an extrinsic calibration problem. The author presents three classes of extrinsic calibration procedures. All use closed-form solutions. The class A calibration procedure requires a reference object at a recalibrated location. The class B calibration procedure takes advantage of robot mobility. It requires a reference frame, but not precalibration. The class C procedure, by taking full advantage of both robot mobility and dexterity, requires no reference object but the simplest one-a visible point. In simulation studies, the class A, B, and C calibration procedures have produced estimates successfully converging to true extrinsic parameter values. Results of field experiments carried out for class B and C calibration procedures are presented. For comparison, two existing B-type calibration methods have also been tested with real data.>

Actual trajectories of robot manipulators usually differ from the planned trajectories partially because of the effects of link deflections and joint compliance. This paper presents an efficient computation scheme to calculate the actual positions and orientations of the end-effectors of manipulators consisting of straight thin-walled hollow links and revolute joints, of which most contemporary robots are made up. Local principal coordinate frames are defined for deflection analysis. Displacements are computed using formulae derived from classical beam theory. For compliance analysis, the robot joints are considered as torsional springs, where the first order approximation is applied. A hypothetical two-link robot is used to demonstrate the techniques. Results are verified by analytical solutions, and the differences are less than 1% of the deflections.

The robot drive system has been previously designed to achieve optimal performance in the acceleration space by matching the gear ratios and actuator impedances. In this paper, the design effort on the robot drive system is continued to achieve the optimal performance measured in the velocity and angular velocity space. Design variables are first identified to be actuator gains. Then, the speed hull geometry of a design is analyzed and an appropriate performance measurement of this design is explored. To locate the optimal design, efficient algorithms dedicated to speed hull constructions are identified and the steepest descent direction, is derived to assist in searching for the optimal design. It is found that the objective function of the optimal design problem is not convex and a local optimal design shouldn't be mistaken as the global optimal design. However, for drive systems built with low gear ratios, the nonlinear effects are negligible and the objective function is convex. Therefore, a local optimal design is the global optimal design.

Robots are employed in flexible manufacturing systems. More robots of better performance are needed for a variety of industrial applications. This paper focuses on designing the manipulator-drive assembly having the desirable properties of quick dynamic response and isotroplc velocity convergence to improve the robot performances and partially satisfy those needs. The design variables are identified to be functions of gear ratios and actuator impedances. An appropriate performance function is proposed and proven to be a convex function of the design variables. A design procedure that optimally matches gear ratios and actuator impedances to achieve quick and isotropic velocity convergence is developed using the algorithm adopted from Nonlinear Programming to search for the global optimal design. Efforts are also attempted to locate good starting points for the search algorithm. The drive system of an already existing manipulator i.e., CMU DD Arm, is redesigned to illustrate the design procedure.