Page 37 - Robotics Designing the Mechanisms for Automated Machinery

26 Introduction: Brief Historical Review and Main Definitions

placed. The drilling head 4 (which can be considered as a two-degrees-of-freedom
manipulator) carries out a complex movement. The horizontal component of this
movement is equal to the rotor's speed Kon the section a-b-c-d. The vertical compo-
nent is made up as follows: fast approach of the drill to the blank on the section a-b
(the drill's auxiliary stroke), drilling speed on the section b-c (processing stroke), and
high-speed extraction of the drill on the section c-d (second auxiliary stroke). As soon
as the second auxiliary stroke has been completed, the opening in the blank has been
processed, and the drill must return to the initial point a to meet the next blank and
begin the processing style. The time of one cycle is:

where L is the linear distance between the pockets. The time t that the drilling head
follows the rotor can be calculated from the obvious expression:

where / is the distance through which the drilling head follows the rotor. The time T
remaining for the drilling head to return is:

Thus, the returning speed (the horizontal component) of the drilling head V l is:

This case combines the two main approaches in automatic machining. Irrespective of
the nature of the conceptual design of the automatic machine, it consists (as was stated
above) of feeding, transporting, inspecting, tooling, and discharging blocks. The design
of these blocks and some relevant calculations will be the subject of our discussion in
the following chapters.

1.5 Nonindustrial Representatives of the Robot Family

In this section we will discuss in brief some robot systems that almost do not belong
to the family of industrial robots, namely,
1. Mobile robots
2. Exoskeletons
3. Walking machines
4. Prostheses
Each of these kinds of special robot can be classified in terms of certain criteria. We
will thus describe the main features of these machines and the principal parameters
and concepts characterizing them.

1. Mobile robots
These devices have a wide range of applications which are often not of an indus-
trial nature. We can classify the types of mobile robotic machines described here in
terms of their means of propulsion, i.e., wheels or crawler tracks.