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As other vehicles, such as airplanes and cars, ships are also believed to become partially or completely unmanned in the next decade or so. This calls for more automation and increased use of robots for monitoring, surveillance, and operation of these ships.

A review of the history of kinematics and machine theory shows a direct connection between the ability to solve polynomial systems using algebraic and numerical techniques and the advancement of the analysis and synthesis of machine systems including robots. Research challenges in kinematic synthesis, compliant mechanisms and cable and tensegrity systems show an ever increasing need for the solutions of complex polynomial systems.

This chapter concerns the design of a human-in-the-loop road vehicle driving simulator. The key components of the driving simulator are the vehicle dynamic model, Stewart platform (parallel manipulator), real-time controller, visual animation system, and human–machine interface. In this chapter, the vehicle model developed in Chap. 6 has been used. The Stewart platform is modeled with its hydraulic actuators. Overwhelming control strategy, developed in Chap. 9, is used to control the platform motion so that it mimics the motion of the virtual vehicle (numerical model) driven through the human–machine interface (driver controls and visual feedback). For implementing the overwhelming controller, a lean inverse dynamics model of the platform has been constructed. It is shown that the overwhelming control strategy is an efficient method of system inversion. It further makes the control system robust against parametric uncertainties such as the platform payload. A simple graphics interface has been developed to render the driver display based on the computed vehicle position, orientation, and terrain data. The results from the developed basic simulator are presented. This chapter introduces the fundamental concepts needed to develop practical vehicle simulator systems.

Planar multibody systems, and revolute and prismatic joints with clearance and friction are initially modeled in this chapter with Rapson slide and Andrew’s mechanism as two examples. For modeling spatial multibody systems, the concepts of noninertial reference frame, Euler angles, and coordinate transformations, etc., are introduced. Hydraulically actuated leg of a Stewart platform and spinning top are modeled as examples. Flexible body systems such as beams, beam columns, composite beams, and bimetallic strips are modeled through spatial discretization and lumped parameter approximation. A thorough treatment is given to modeling of piezoelectric actuators and sensors. Thereafter, models for various microelectromechanical systems (MEMS) like micromirrors, micromotors, magnetohydrodynamic micropumps, wet shape memory alloy (SMA) actuator, and energy harvesting systems, etc. are developed. Further, models of rotor-bearing systems with rolling element, journal, and magnetic bearings are developed with special emphasis on active magnetic bearing model. The importance of integrated modeling is shown by considering the case of Sommerfeld effect in a rotor dynamic system and its control through shape memory alloy actuators.

In the past recent years parallel robots have drawn a lot of interest in the robotics community and in many applicative domains: medical, machine-tools, pick-and-place,etc, where the advantages (e.g. accuracy, rigidity) of closed-loop chains may be useful. The purpose of this paper is to identify important open theoretical problems in this field.

The Tetrahedral-Tripod is a novel spatial, parallel-link manipulator that offers pure translational motion. In this paper we describe the ideas leading to the development of low degree-of-freedom parallel link mechanisms for use in machine tool applications. The tetrahedral tripod offers superior theoretical characteristics by admitting closed-form solutions for its kinematics and dynamics. Further, its motion and mechanical construction are simple while offering high stiffness and accuracy. It offers a relatively large, singularity-free workspace. It may be used as the basis of a 3-axis machine tool. When used in conjunction with a universal table, it offers the potential for a stiff and accurate 5-axis, series-parallel machine tool. Keywords. Parallel link manipulators, Stewart platform, Machine tools.

The design of high performance machine tools is a challenging task because competing objectives and tight constraints leave little margin for error in the design process. The hexapod is no exception, especially when the objective is to design it as a platform for high-speed machining. When Stewart Platform machines first emerged as a possible machine tool configuration in the early nineties, there was considerable excitement in the machine tool user community about the possibilities they would open up. Machine tool users perpetually seek faster, stiffer and more accurate machines with smaller footprints and greater dexterity, and Stewart Platforms are known to have these attributes. However, designers have always realized that these objectives compete, and informed tradeoffs need to be made to optimize hexapod machine tools for the particular application. The fact that several hexapod machine tools are now in operation in companies, universities and research laboratories worldwide is a testament to the abilities of the design community. However, the tradeoffs in the design of hexapod are mathematically inescapable, and this usually leads to quirks in performance such as an oddly shaped workspace or varying speed capability in the workspace. The goal of our research at MIT is to develop ancillary technologies that permit the effective use of hexapods in the face of these challenges.

Unchained from the confines of controller limitations, the industrial application of parallel kinematic machines in manufacturing is beginning to emerge. The launch of commercially available hexapod machine tools at the 1994 International Manufacturing Technology Show in Chicago represented the first radical departure in machine tool design since the introduction of numerical controls. The parallel actuator technology promises to offer manufacturers a number of advantages relative to conventional machine tools, such as a higher stiffness-to- mass ratio, higher speeds, higher accuracy, reduced installation requirements, and mechanical simplicity. Several machine tool makers in the U.S. and around the world are pursuing parallel actuator technology, while their prospective customers — manufacturers — are beginning to contemplate what the novel multi-axis machining technology might mean for their operations.

This paper describes the measurement and analysis of the quasi-static errors of a prototype hexapod milling machine located at the National Institute of Standards and Technology (NIST). Emphasis is placed on a) identification of the most important parametric errors and their potential impact on performance, b) description of the techniques used to measure and estimate the parametric errors, and c) application of various concepts to model the geometric and thermal errors of the hexapod.

Even if parallel kinematics for machining application must still prove their authorisation on the market, the first prototypes show that turning away from conventional solutions leads to interesting and promising alternatives. However, in contrast to conventional serial machines, whose technology is well developed in detail, the implementation of new kinematic concepts requires the development of new problem-specific technical solutions. This contribution points out the substantial features of this new machine generation with special focus on structurally caused problems in design, control and calibration. Possible solutions, which have been worked out at WZL are presented by the example of the Ingersoll Octahedral Hexapod and the Dyna-M concept.

In the last recent years parallel structures have found applications outside the field of Flight simulator: machine-tool, virtual reality, fine positioning devices, etc.. For each of these applications the performances requirements are quite different. It is therefore very important to design parallel structure in accordance with the considered application, especially as for this type of mechanism the performances vary heavily according to the mechanical architecture and its dimension. We will present some design problems in order to show that optimal design for parallel structure is an open and difficult problem.

For higher accuracy of parallel kinematic robots and machine tools in particular, several error models and compensation algorithms have been developed. The paper presents the approach for testing and control of Stewart platform-based machine tools and robots. The approach is based on serial link measuring system with six DOF in general, which may be used as an autonomous measuring device or in symbiosis with parallel kinematic machines to achieve Cartesian-based control schemes. Developed approach is demonstrated and verified on the example of developed planar parallel simulator with three DOF.

The control of high-speed motion of a machine tool structure based on the parallel link Stewart platform kinematic structure is addressed here. A model- based decoupling and linearizing algorithm is used in Cartesian space, measurements in this space being derived in real time from joint space measurements by an approximate solution of the forward kinematic relationships. A cross-coupled control formulation is then used to transform the control problem to decoupled control in task space coordinates. Control approaches are then applied to direct the control effort primarily at reduction of task space errors critical for machining tasks. The control algorithms developed thus are applied to a computer simulation of the dynamic response of a Stewart platform based machine tool structure as it executes a number of representative trajectories at feed rates of up to 12 m/min. The simulation results demonstrate the effectiveness of the proposed control algorithms and are presented here.

This paper describes the use of an inertial navigation system in conjunction with a Kaiman filter to estimate crane load sway. The estimator was based on a simple dynamic model of the crane yaw motion. Experiments were conducted on a l/15 th geometric scale model of a quay-crane. The performance of the filter was assessed using data obtained from video images. A yaw position estimator was able to track accurately the motion of the load over extended time periods.