Masih Mahmoodi

• PhD
• Researcher at Vineland Research and Innovation Centre

Nonmodal model order reduction (MOR) techniques present accurate and efficient ways to approximate input-output behavior of large-scale mechanical structures. In this regard, Krylov-based model reduction techniques for second-order mechanical structures are typically known to require a priori knowledge of the original system parameters, such as exp...

The accuracy of a parallel kinematic mechanism (PKM) is directly related to its dynamic stiffness, which in turn is configuration dependent. For PKMs with kinematic redundancy, configurations with higher stiffness can be chosen during motion-trajectory planning for optimal performance. Herein, dynamic stiffness refers to the deformation of the mech...

Parallel kinematic mechanisms (PKMs) provide high stiffness and compact structures that are suitable for a large number of applications, including 5-axis milling. This paper presents a new pentapod-based PKM with an additional redundant degree-of-freedom (DOF) capable of reaching platform tilt angles of at least 90 deg over a large workspace. The p...

Research and biomedical applications in cell surgery require transportation and rotation of biological cells. In these cell manipulation tasks, the cell of interest must be translated and oriented properly such that the desired component, such as the polar body or other organelles, can be imaged with optical microscopy. This paper presents a hologr...

The accuracy of various admissible shape functions, for vibration modeling of flexible links of Parallel Kinematic Mechanisms (PKMs), is investigated as a function of the ratio of the mass of the moving platform to the mass of the link. Knowing that the commonly used shape functions based on "pinned", "fixed", or "free" boundary conditions do not i...

A new modified integral resonant control (IRC) scheme is demonstrated herein for vibration suppression of the flexible links of parallel kinematic mechanisms (PKMs). Typically, the resonance frequencies and response amplitudes of the PKM links experience configuration-dependent variation within the workspace. To address these variations, a robust q...

This thesis is concerned with modeling of structural dynamics, dynamic stiffness, and active control of unwanted vibrations in Parallel Kinematic Mechanisms (PKMs) as a result of flexibility of the PKM linkages. Using energy-based approaches, the structural dynamics of the PKMs with flexible links is derived. Subsequently, a new set of admissible s...

Parallel Kinematic Mechanisms (PKMs) are well suited for high-accuracy applications. However, constraints such as end-effector rotation (i.e., platform tilt angle) and configuration-dependent stiffness often limit their usage. A new six degree-of-freedom (dof) PKM architecture based on a 3×PPRS topology that addresses these concerns is presented in...

In this paper, passivity-based methods are used to perform tracking control of flexible robot manipulators subject to impact collision. The model taken for colliding system is an n-degree of freedom body moving in the manipulator’s workspace. Impulsive forces generated in the course of impact cause sudden changes in velocity/acceleration of the lin...

In this paper, dynamic equations of a robot manipulator subject to compliant contact/impact with the environment are derived using nonlinear elastodynamic approach. Then, a sliding mode impedance algorithm is proposed to control compliant impact/contact dynamics of the robot manipulator with an arbitrary environment. Impact/contact phenomenon can b...

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

In this paper, a detailed dynamic model for a general parallel kinematic mechanisms (PKM) used in a reconfigurable meso-milling machine tool (RmMT) is developed in terms of active joint coordinates via the Lagrange formulation and appropriate coordinate transformations. The proposed dynamic model is, then, implemented numerically on a 3-PPRS parall...