**6. References**

122 Serial and Parallel Robot Manipulators – Kinematics, Dynamics, Control and Optimization

design and choice of the leg strokes and mean lengths. Also as an alternative configuration, the 2-DOF wrest joint that hold the spindle could also be replaced by a 2-DOF rotary table, transferring the relative rotational motion to the workpiece. A redundant hybrid structure consisting of a hexapod machine tools and a 2-DOF rotary table is suggested and analyzed

The considerable interest that is shifted to hybrid kinematic structures to exploit the advantageous features of the serial and parallel kinematic structures and avoiding their drawbacks has brought about some interest in overconstrained hybrid mechanisms. A study on the mobility of the three classes of mechanisms is presented and focuses on the mobility of overconstrained structures in view of their application in parallel and hybrid structures to reduce the number of passive joints. The mobility of the Exechon mechanism is analyzed and discussed as an example of a successful machine tools mechanism. The study of this mechanism reveals that its 3-DOF parallel kinematic part is a revolving 2-DOF planner mechanism. Strategies for kinematic designs of planner parallel mechanisms were developed and discussed based on the axiomatic design methodology. Optimum configurations for planner mechanisms were presented for 2-DOF planner mechanisms and were shown to be extendable to 3-DOF planner and spatial mechanisms by proper choice of joints and constraints. An alternative optimum parallel and hybrid mechanism is discussed

by Harib et al. (2007).

**4. Conclusions** 

and analyzed.

FR11

Wrest joint gives required orientation capabilities

Fig. 10. Main Function Requirements of a hybrid design

FR121 Adequate and consistent dexterity

FR 1

Positioning and orientation capabilities

> FR122 Good structural rigidity

Parallel mechanism gives required positioning capabilities

FR12

FR123 Large and well shaped workspace


**7** 

*Spain* 

**Design and Postures of a Serial Robot** 

David Úbeda, José María Marín, Arturo Gil and Óscar Reinoso

*Universidad Miguel Hernández de Elche* 

**Composed by Closed-Loop Kinematics Chains** 

The robot presented in this chapter is a new binary hybrid (parallel-serial) type climbing system composed by several closed-chains arranged in an open-chain. The originality of the robot resides in the possibility of combining several parallel modules to build a new configuration of the robot according to the intended application. In this chapter, one possible morphology will be covered, destinated to climb metallic cross-linked structures, but we will also study the kinematics and the structure of the simplest modules apart

Hybrid climbing robots are hard to find, but hybrid climbing robots with binary actuators are still less common. In our opinion, binary actuators are interesting, since they allow for an easier control of the robot: only two different positions need to be controlled. This advantage comes at a price, since less points in the workspace can be reached, but hereby, large motion workspace, small volume and multiple degrees of freedom will be some of the

In the robot proposed in this chapter, the activation of every lineal actuator of the closedloop generates a planar and rotational movement of the output link respect to the input one. Several parallel modules can be connected in a serial mode. In this sense, the robot is freely

A great variety of applications can be reached with the final 2+2 closed-chain disposed in a

As it was mentioned above, it is possible to build complex structures combining parallel modules. Attending some researches, it is not difficult to find many papers of climbing or walking robots (Qi et al., 2009; Nagakubo & Hirose, 1994; Aracil et al., 2006b), but mostly adopt serial mechanism, what makes them less robust and with compromised stability. However, few authors have researched about the use of the hybrid mechanisms to add the desired characteristics with a simple and sensor-less control (Lichter et al., 2002; Chen & Yeo, 2002; Lees & Chirikjian, 1996; Erdmann & Mason, 1988; Goldberg, 1989; Craig, 1989). The mechanism proposed combines parallel modules to set up a climbing robot, in addition with improve the mentioned characteristics, to outfit the robot with best stability and

Another main feature that contributes originality compared with the related works of similar robots, it is aimed to a discrete workspace. Also we will demonstrate that it is possible to reach enough points to accomplish the required application (climb metallic

reconfigurable, thus, new modules (translational or rotational) can be added.

new challenges of this kind of robots (Lichter et al., 2002).

**1. Introduction** 

from the final robot.

serial mode proposed system.

strength.

