Common assumptions in most of the previous nonlinear networked leader–follower systems are that the leader is provided as a constant signal and that the controllers are designed for either the joint-space regulation or the translational Cartesian-space motion control. This article addresses the control issue of the delay-induced horizontal shift effect when the leader is moving with a changing speed. A novel mixed-type feedback is introduced to reduce the horizontal shift effect so as to minimize tracking errors experienced by the follower agents. In this article, we also study the complete pose control using a nonsingular terminal sliding mode (NTSM) method. A stability analysis is provided to prove the finite-time boundedness of the tracking error signals. Quantitative evaluations of the multiple effects on the error bound are conducted to facilitate the subsequent control design to improve the performance. Numerical simulation results of a team of two degree-of-freedoms (DOFs) manipulators demonstrate the improved tracking performance of the end effectors with small bounded errors which are affected by network delays, maximum assigned accelerations, and the selection of control gains. The experimental results are provided to demonstrate the performance of the developed controller.

Time domain passivity control (TDPC) is a widely used reliable approach to ensure the stability of the teleoperation systems. Although TDPC almost guarantees the stability of the system, there can be a possibility of instability as TDPC inherits the zero division problem in its conventional control laws. Low value force or velocity signals can lead to zero division in control laws and can be a reason of control failure. As a multilateral teleoperation system is much more complex as compared to a bilateral teleoperation system due to increased number of masters and slaves, increased transmission of signals over a communication network as well as multiple human operators so it is substantially invaluable to have a control scheme which ensures a safe and stable operation. This paper, an extension of our previous work, presents a novel design of TDPC laws for multilateral teleoperation which not only maintains the passivity of the system for stability but also avoids zero division thus guaranteeing a stable operation. A new architecture of communication channel is introduced to assign different weights to the masters and slaves depending upon the task requirements. The control strategy proposed in this paper is valid for different numbers of masters and slaves. Simulation and experimental results are presented to demonstrate the efficacy of the control design.

Conventional time domain passivity control inevitably embodies division. Zero division can occur under a tiny force or velocity, which may be inevitable, and will be the cause of control crash. To avoid the zero division problem and control crash, we propose a switching dissipation controller for guaranteed stability. The parametric design of the proposed approach is discussed. The switching time domain passivity control is then applied to teleoperation and safe operation is achieved. Simulation and experimental results are demonstrated to validate the effectiveness of the proposed control scheme.

We are going to design and simulate low power fractional-N phase-locked loop (FNPLL) frequency synthesizer for industrial application, which is based on VLSI. The design of FNPLL has been optimized using different VLSI techniques to acquire significant performance in terms of speed with relatively less power consumption. One of the major contributions in optimization is contributed by the loop filter as it limits the switching time between cycles. Sigma-delta modulator attenuates the noise generated by the loop filter. This paper presents the implementation details and simulation results of all the blocks of optimized design.

Time domain passivity control, a well known control scheme widely used for teleoperation systems, normally works under the constraint of zero division. Small force or velocity signals can cause the occurrence of zero division which ultimately leads the system to be unstable. This paper presents a novel switching time domain passivity control scheme for multilateral teleoperation systems which not only ensures the stability of the system but also avoids zero division. In contrast to bilateral teleoperation systems, the multilateral teleoperation system is much more complex as it involves increased number of master and slave hardware, multiple operators and transmission of multiple signals over the communication network. A new framework for the communication channel has been proposed which incorporates the use of weighting coefficients to give the masters and slaves authority depending upon the requirements of the operation. As the switching time domain passivity control keeps the system passive all the time, the stability is guaranteed. The proposed control scheme is valid for n masters and n slaves. Simulations with two masters and two slaves are carried out to verify the effectiveness of the proposed scheme.