K Sridharan

In this chapter, we present key aspects of the CNTFET technology. As indicated earlier, carbon nanotubes have bandgaps that are dependent on the diameter of the tubes [1]. Also, the bandgap turns out to be a measure of the threshold voltage of the CNTFET.

This paper presents two efficient ternary SRAM designs appropriate for several transistor-based technologies. The first design is based on the cycle operator in ternary logic while the second is a buffer-based design that employs the positive and negative ternary inverters. Both the designs consume low power in comparison to existing standard ternary inverter-based SRAM designs. Further, the read and write delay for the proposed designs are much lower than the corresponding ones for existing designs. Detailed analyses of the proposed circuits are presented. Extensive HSpice simulations (and comparisons) using a Carbon Nanotube Field Effect Transistor library are reported. The proposed designs also have noise margins comparable to existing designs.

This research has studied digital design in the context of emerging nanotechnologies. In particular, we have studied the problem of designing arithmetic circuits in Carbon Nanotube Field Effect Transistor technology. We have presented a number of theoretical results on ternary logic. The results facilitate reduction of transistor count for various circuits. We now list the contributions and touch upon extensions to the work.

We have discussed the design of CNTFET-based adders in the earlier chapters. In this chapter, we present the design of a ternary multiplier. We note that the design of a single-digit multiplier itself is non-trivial in the ternary setting.

In previous chapters, we have developed CNTFET-based designs for specific operations such as addition and multiplication. We provided various “thumb-rules” for reducing the transistor count. In this chapter, we attempt to answer the following question: Can the process of synthesis be automated ? We provide an outline of an automatic synthesis procedure and also touch upon coding in Python. A study of the synthesis problem is also pursued in [1].

Safety considerations call for deployment of autonomous ground vehicles in defense and high risk zones for transport of goods from one point to another. Such vehicles face the threat of an intelligent autonomous adversary that may disrupt the transfer of material. This article investigates the challenges involved in autonomous protection of a delivery agent, via a land-based rescue agent, before interception of the delivery agent by the adversary occurs. In particular, we study how effectively an adversary equipped with a vision sensor can be handled by an autonomous rescue agent operating without vision support and relying only on wireless communication with the delivery agent. Taking capabilities and weights of the three vehicles into account, the delivery agent is assumed to be the slowest while the adversary operates at the highest speed among the three vehicles. A geometric framework based on Apollonius circles is proposed to analyze the interaction between the delivery and rescue agents. The adversary's speed and its moves (based on the direction of the delivery agent) are taken into account, along with the Apollonius circles for the rescue-delivery agent pair, to determine the possibility of capture. Regions in the plane where the delivery and rescue agents can meet, prior to a capture by the adversary, are obtained to compute safe regions for the delivery agent. Algorithms adopted by the delivery agent, rescue agent, and the adversary are described. We, then, explore the challenges in rescue of multiple delivery agents from a vision-guided adversary by introducing additional rescue agents. In particular, we study protection of k delivery agents (from an adversary) via k rescue agents. Algorithms to compute 1) multiple meeting points, one each for a delivery agent-rescue agent pair and 2) the strategy of the adversary to capture any one of the k delivery agents are presented. Experiments with multiple agents show that the delivery and rescue agents can execute their strategies using simply low-end microcontrollers without external memory.

Collision detection and avoidance are vital sub-tasks in any autonomous robotic task. This work presents a technique that guarantees collision avoidance in an environment containing multiple agents. These agents can be of different types such as static, dynamic obstacles and other robots. The technique supports parallel implementation and is appropriate for real-time applications. In this work, the theory of interval arithmetic is used to represent the pose of agents as intervals in a fixed time period. Geometrically, the intervals correspond to finite-length arcs and line-segments. Theoretical results on the inclusion of one interval, in another interval, in terms of sub-intervals are derived. Breaking down the problem in sub-intervals supports parallelism in performing multiple interval inclusion tests and in handling multiple agents. The proposed interval-arithmetic based framework leads directly to a hardware-efficient collision detection scheme. In particular, the proposed strategy admits a solution even for a dynamic environment using just shift and add capability, an important aspect for embedded implementation. The solution of interval inclusion is also used to find a set of solutions for guaranteed collision avoidance with multiple agents with known or unknown trajectories. Simulation results in MATLAB and experiments with an FPGA-driven differential drive mobile robot demonstrate the versatility of the proposed approach.

In previous chapters, we have developed CNTFET-based designs for arithmetic operations such as addition and multiplication. In this chapter, we provide detailed simulation results for various circuits developed in the earlier chapters.

Just as we add two bits in a (binary) half-adder and three bits in a (binary) full-adder, one can consider addition of two or three ternary digits. The addition of two ternary digits is expressed by Table 4.1. The extension to three ternary digits is presented in Table 4.2.

The effect of addition of nanoparticles to silicone rubber is studied in this paper in the context of soft robotic applications to transmission line maintenance. Silicone rubber and polylactic acid (PLA) are used in the fabrication of these robotic structures. Desirable characteristics for the materials making the structure are (i) Low surface charge and space charge accumulation and (ii) High tensile and tear strength. To meet these requirements, addition of nano MgO to silicone rubber is proposed and studies pertaining to surface potential variation, space charge variation and dielectric parameters are performed. It is observed that 3wt% MgO added silicone rubber shows better performance than pure silicone rubber. Further, silicone rubber/MgO nanocomposite sandwiched PLA shows least space charge at the electrodes and at the interfaces of the sandwich. Moreover, the mechanical properties are also enhanced via the addition of nano MgO. In particular, 3wt% MgO added silicone rubber shows maximum tensile and tear strength. A direct correlation between tear strength and Shore A hardness is also observed. In addition, substantial improvement in viscoelastic properties of silicone rubber is observed with the addition of nano MgO.