SummaryThis paper aims at estimating the tremor torque using extended Kalman filter (EKF) applied to a two-link 3-DOF robot with nonlinear dynamics modelled using Lie-group and Lie-algebra theory. Later, it is generalised to d number of links with (d + 1) -DOF. The configuration of each link at any time is described by its rotation relative to the preceding link. Using this formulation, an elegant formula for the kinetic energy of the (d + 1) -DOF system is obtained as a quadratic form in the angular velocities with coefficients being highly nonlinear trigonometric functions of the angles. Properties of the Lie algebra generators and the Lie adjoint map are used to arrive at this expression. Further, the gravitational potential energy and the torque potential energy are expressed as nonlinear trigonometrical functions of the angles using properties of the SO(3) group. The input torque comprises a nonrandom intentional torque component and a highly nonlinear tremor torque component. The tremor torque is modelled as a stochastic differential equation (sde) satisfying Ornstein–Uhlenbeck (OU) process with diffusion and damping coefficients. Further, the tremor is treated as the disturbance. The Euler–Lagrange equations for the angles are derived. These form a system of sdes, and the EKF is used to get a more accurate disturbance estimate than that provided by the usual disturbance observer. The EKF is based on noisy angle measurements and yields as a bonus the angle and angular velocity estimates on a real-time basis. The parameters in the OU process model of the tremor torque, and parameters of the Fourier components of the intentional torque have also been estimated.

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Abstract:Now a days MITMA is very harmful for the user of internet. This paper is describe the different effect of MITMA. We also discuss about various method from prevention of MITMA. Abbreviated as MITMA, a man-in-the-middle attack is an attack where a user gets between the sender and receiver of information and sniffs any information being sent. In some cases, users may be sending unencrypted data, which means the man-in-the-middle (MITM) can obtain any unencrypted information. In other cases, a user may be able to obtain information from the attack, but have to unencrypt the information before it can be read. In the picture below is an example of how a man-in-the-middle attack works. The attacker intercepts some or all traffic coming from the computer, collects the data, and then forwards it to the destination the user was originally intending to visit I. INTRODUCATION .In cryptography and computer security, a man-in-the-middle attack (often abbreviated to MITM, MitM, MIM, MiM attack or MITMA) is an attack where the attacker secretly relays and possibly alters the communication between two parties who believe they are directly communicating with each other. Man-in-the-middle attacks can be thought about through a chess analogy. Mallory, who barely knows how to play chess, claims that she can play two grandmasters simultaneously and either win one game or draw both. She waits for the first grandmaster to make a move and then makes this same move against the second grandmaster. When the second grandmaster responds, Mallory makes the same play against the first. She plays the entire game this way and cannot lose. A man-in-the-middle attack is a similar strategy and can be used against many cryptographic protocols.[1] One example of man-in-the-middle attacks is active eavesdropping, in which the attacker makes independent connections with the victims and relays messages between them to make them believe they are talking directly to each other over a private connection, when in fact the entire conversation is controlled by the attacker. The attacker must be able to intercept all relevant messages passing between the two victims and inject new ones. This is straightforward in many circumstances; for example, an attacker within reception range of an unencrypted Wi-Fi wireless access point, can insert himself as a man-in-the-middle. [2] As an attack that aims at circumventing mutual authentication, or lack thereof, a man-in-the-middle attack can succeed only when the attacker can impersonate each endpoint to their satisfaction as expected from the legitimate other end. Most cryptographic protocols include some form of endpoint authentication specifically to prevent MITM attacks. For example, TLS can authenticate one or both parties using a mutually trusted certificate authority. [3]

In this paper, a novel statistical application of large deviation principle (LDP) to the robot trajectory tracking problem is presented. The exit probability of the trajectory from stability zone is evaluated, in the presence of small-amplitude Gaussian and Poisson noise. Afterward, the limit of the partition function for the average tracking error energy is derived by solving a fourth-order system of Euler–Lagrange equations. Stability and computational complexity of the proposed approach is investigated to show the superiority over the Lyapunov method. Finally, the proposed algorithm is validated by Monte Carlo simulations and on the commercially available Omni bundleTM robot.