2.?Parallel Robot Y-27632 clinical DesignA classification of the most well-known parallel robots depending on their number of DOF can be found in [13,14]. This section shows some examples of parallel robots, classified by the number of DOF, focusing mainly on the new prototypes developed in the last ten years. Most of them are based on the Stewart platform. Table 1 presents the symbols used for denominating Inhibitors,Modulators,Libraries the different joints:Table 1.Joint symbols.2.1. Two-DOF DesignsThere are little literature focusing on 2-DOF spatial parallel mechanisms. An analysis of different alternatives of 2-DOF rotational parallel systems can be found in [15]. The kinematic chains, joined to the fixed and moving platforms, result in mechanisms with from 3- to 6-DOF. To reduce the number of DOF to 2, constraints must be added.

Figure 1(a) shows the Canterbury Tracker by Dunlop [16], an antenna tracking mechanism, in which two kinematic chains are joined to the platform by revolute joints and the third chain is connected via spherical joints, thereby obtaining the azimuth and elevation movements. The Omni-Wrist of Rosheim [Figure 1(b)] in [17], is a new 2-DOF system in which two actuators connecting Inhibitors,Modulators,Libraries two plates control a passive plate. This system is able to turn 90 degrees without singularities and it is used in applications such as positioning antennas or robotic surgery. Zeng [15] developed a family of 2-DOF rotational parallel mechanisms and analyzed their mobility. All these systems have a four-bar linkage and contain a moving platform and a fixed base connected by three limbs.

An example of parallel mechanism is presented in Figure 1(c). This is a system with three chains U-PRU-SPS where the motion of the moving platform is decoupled. Computation Inhibitors,Modulators,Libraries is simple and Inhibitors,Modulators,Libraries the system allows us to perform a fast real-time control.Figure 1.Two-DOF parallel robots: (a) Dunlop design (reprinted from [16] with permission from Elsevier). (b) Omni-wrist from Rosheim [17] (reprinted with permission from Rosheim). (c) Zeng design (reprinted from [15] with permission from IEEE). (d) Majarena design …In [18], Majarena designed a pan-tilt parallel platform for the positioning and orientation of two high-precision cameras. This mechanism has two actuators Dacomitinib and two linear optical sensors joined to the base and to the platform by high-precision spherical ball joints.

The mechanism incorporates a third chain, which is fixed to the base and joined to the platform by a universal joint to obtain the two rotations desired [see Figure 1(d)]. The sensor accuracy is ��1 ��m. Given a measurement field of the 2-DOF structure and fixed sensors, a method to use these sensors to increase the angle http://www.selleckchem.com/products/Bosutinib.html resolution within this measurement field is presented. The aim of the study is to develop a methodology for improving the mechanism design.