This document discusses various methods of teaching and programming industrial robots. It describes four basic methods: 1) Walk-through teaching or pendant teaching, where the user guides the robot arm to positions using handheld controls and stores the joint positions. 2) Lead-through teaching, where the user physically moves a master arm to record a path that the robot then replays. 3) Offline programming, where a program is typed in with commands like "move axis A distance D". 4) Programming pick and place machines by setting mechanical end stops and programming the sequence of joint movements. The document provides details on each method and their implications.

6. Methods of teaching and programming
How does an industrial robot determine
what movement to make next?
There are two extreme possibilities:
the movement is calculated at the time,
or it is replayed from an existing
program or recording.

7. •The first method is necessary if the robot is to
respond continuously to sensory inputs, e. g .
if it is to follow a surface using a proximity sensor.
An intermediate case is for the program to have
branches selected by sensor signals, or to accept
certain values, such as a desired gripper rotation
angle, from an external source .

8. • Such a robot is always driven by a program,
whether this is a sequence of indivisible
actions, a sequence of target positions or a
continuous record of position or velocity.
• four basic methods of teaching and
programming

9. PROGRAMMING PICK AND PLACE
ROBOTS
• The crudest form of programming is the setting
up of a pick and place machine.
• This has two parts: the mechanical end stops are
set in place for each axis, and the sequence in
which the joints operate is programmed.
• The sequencer on early machines was a
mechanical device such as a multi position rotary
switch with several cams on its spindle, each cam
operating contacts to switch power to the
solenoid valves for the pneumatic cylinders.

10. PROGRAMMING PICK AND PLACE
ROBOTS
• controllers allow the storage of several
programs, and these may have subroutines
and allow a wide choice of time delays
between actions.
• One controller may be able to handle several
robots in a coordinated way, and to interlock
their operation with that of other machinery.

11. WALK-THROUGH TEACHING OR
PENDANT TEACHING
• This is the most usual method with point to point
servo robots. A handheld box or 'pendant' has
buttons, toggle switches or joysticks
corresponding to each axis of the arm, which
cause the axis to be driven under power.
• The user drives the robot to a required position
using these controls and then presses a button
which causes all the joint position sensors to be
read and their values stored

12. This method of teaching has certain consequences
not obvious at first sight.
An important one is that since the path between
two programmed points is unspecified, and since
there will usually be several joints active at once,
the arm may not approach a target point from the
same direction as it did during teaching. Therefore
an extra point is often inserted into a program so
that the approach to a critical point requires
movement of just one axis. Intermediate points
are also inserted to take the path round obstacles.

13. WALK-THROUGH TEACHING WITH
PATH CONTROL
• When the user has entered two points on the
desired path, the robot's computer calculates
a straight line between the points which the
robot can follow, at a speed chosen by the
user, at playback time.
• An example of its uses is in paint spraying in
cases where there are long straight runs of
the spray gun, which can be specified by
teaching just the start point and end point of
the run.

14. LEAD-THROUGH TEACHING OR
PHYSICAL ARM LEADING
The user carries out the required motions with his own hand,
while holding some device for recording the path taken.
This device may be the manipulator itself or a replica arm, the
'master arm‘ or 'teaching arm', which is geometrically similar
to the robot but is light enough to move easily, is unpowered
and has angular or displacement sensors on its joints similar
to those on the robot.
The signals from these are recorded and become the program
which the robot plays back. The program can be replayed at a
fraction or multiple of the speed at which it was recorded.

15. OFF-LINE PROGRAMMING
• The alternative to teaching a robot by driving
it through its cycle of operations is to type in a
program at a computer terminal.
• In the simplest case the program consists of a
series of commands of the form 'move axis A
through distance D

16. THE IMPLICATIONS OF SENSING FOR
ROBOT CONTROL

17. Analysis and Control
• Analysis means finding a mathematical
description of a robot in relation to its
surroundings, which will allow the calculation
of the geometric and dynamical quantities
used in controlling it.
• Control in the sense of this and the following
sections means operating the robot's
actuators so as to produce a specified path
and velocity of the payload.

18. • It is nearly always assumed that a robot can
be regarded as a chain of rigid links connected
by revolute or prismatic joints at which
actuators, regarded as torque or force
generators, act.
• With this assumption, there is a set of
important problems in analysis and control……
They are….

19. • formulating the kinematic equations (joint coordinates to
world coordinates)
• solving the kinematic equations (world coordinates to
joint coordinates);
• the forward problem of dynamics - finding the motions
resulting from joint torques;
• the inverse problem of dynamics - finding the torques
needed to produce a given motion;
• specifying a trajectory between target points on the path;
• actuator servo control - for a single actuator, how to drive
it
• so as to produce a specified position, velocity or torque.

20. FORMULATING THE KINEMATIC
EQUATIONS
• Kinematics is concerned with distances and
angles and translational and angular velocities
and accelerations, but not with forces, masses,
torques and moments of inertia, which are the
province of dynamics.

21. • A three dimensional coordinate system is
embedded in each link, as shown in Figure 3.3.
For each joint a transformation is found
between the coordinate system of the two links
it connects; if this operation is applied to each
joint in succession, the relationship between
any two links, including the payload and the
fixed base of the robot, can be found. These
transformations are expressed as equations
called the kinematic equations of the
manipulator

22. • It is convenient to use homogeneous
coordinates for the system of each link, and in
this case the kinematic equations take the
form of matrix multiplications. Therein lies
their advantage, for a chain of transformations
is simply a chain of matrix multiplications and
so the relationship between any two links is
easily expressed.

23. SOLVING THE KINEMATIC EQUATIONS