TAILIEUCHUNG - Ebook Mechanical engineering series (3rd edition): Part 2
(BQ) Part 2 book "Mechanical engineering series" has contents: Dynamics of serial robotic manipulators, special topics in rigid body kinematics, geometry of general serial robots, kinematics of alternative robotic mechanical systems, trajectory planning - continuous path operations, dynamics of complex robotic mechanical systems. | Chapter 7 Dynamics of Serial Robotic Manipulators Introduction The main objectives of this chapter are (^) to devise an algorithm for the realtime computed-torque control and (ii) to derive the system of second-order ordinary differential equations (ODE) governing the motion of an n-axis manipulator. We will focus on serial manipulators, the dynamics of a much broader class of robotic mechanical systems, namely, parallel manipulators and mobile robots, being the subject of Chapter 12. Moreover, we will study mechanical systems with rigid links and rigid joints and will put aside systems with flexible elements, which pertain to a more specialized realm. Inverse vs. Forward Dynamics The two basic problems associated with the dynamics of robotic mechanical systems, namely, the inverse and the forward problems, are thoroughly discussed in this chapter. The relevance of these problems cannot be overstated: the former is essential for the computed-torque control of robotic manipulators, while the latter is required for the simulation and the real-time feedback control of the same systems. Because the inverse problem is purely algebraic, it is conceptually simpler to grasp than the forward problem, and hence, the inverse problem will be discussed first. Moreover, the inverse problem is also computationally simpler than the forward problem. In the inverse problem, a time-history of either the Cartesian or the joint coordinates is given, and from knowledge of these histories and the architecture and inertial parameters of the system at 258 7. Dynamics of Serial Robotic Manipulators hand, the torque or force requirements at the different actuated joints are determined as time-histories as well. In the forward problem, current values of the joint coordinates and their first time-derivatives are known at a given instant, the time-histories of the applied torques or forces being also known, along with the architecture and the inertial parameters of the .
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