1. Landstown High School Governors STEM & Technology Academy
Advanced Robotics
Chapter 5- Electromechanical Systems
Dr. Barger

2. History and Background
Originally, all manufacturing operations were manually controlled using:
Gas-filled tubes,
magnetic contacts,
and electrical switchgears,
With the development of electronics, advances to control devices have occurred,
Electromechancial,
Optoelectronic,
hydraulic,
Pneumatic,

3. Automated Systems and Subsystems
Almost all manufactured products are produced using some type of electromechanical system.
Definitions:
A “System” is a combination of components that work together to form a “unit”.
A “Subsystem” is a component that comprises, or make up, the complete robot.
When “Subsystems” are combined the result is defined as a “synthesized system”.
Examples of subsystems:
Electrical power, hydraulic or pneumatic systems, optoelectronic systems, mechanical systems.

4. Automated Systems and Subsystems
Even though each “System” is unique there are some basic subsystems common to all automated systems:
Energy source,
Transmission path,
Control,
Load,
Indicators.

5. Mechanical Systems
A mechancial system produces some form of mechanical motion,
Three basic types of motion are usally used:
Rotary motion (motors),
Linear motion (relays, actuators, and cylinders),
Reciprocation ( motors and cylinders that usally move vertically),
The energy source for these systems is usally electrical or fluid power (hydraulic or pneumatic)
Control of these systems is accomplished by changing,
Pressure,
Direction,
Force, or
Speed.

6. Electrical Systems
There are four basic types of electrical systems used in robots,
Sensing,
Timing,
Control, or
Rotary motion (motors).

7. Sensing Systems
A sensing system signals a response to a particular form of energy,
Incandescent lamps,
Flames,
Glow lamps,
Electric arcs,
Laser light,
Other types could include:
Sound,
Pressure,
Flow and
Magnetic,

8. Conveyor Sensing System
LS 5-1

9. Timing Systems
Timing Systems turn a device on or off, at a specific time or in step with an operating sequence. Types include:
Delay timing,
Provide a lapse in time before the load device becomes energized.
Interval timing,
Is used after a load has been energized and operate using specfied time intervals.
Cycle timing,
Is typically more complex and may include both interval and delay timing systems.

10. Control Systems
Control of an automated manufacturing system (robot) is carried out by human input, or automatically due to some type of physical change.
How complex these changes are is determined by how complex the operation is that the robot is trying to perform.
Open-loop control systems are the most basic and are using found in two varations:
Full control,
Simply turns a system on or off,
Partial control,
Partial control alters the system operation, rather than turning it on or off,

11. Closed-loop System
In automatic control, interaction between the control unit and the controlled load must occur.
LS 5-2

12. Closed-loop System with Automatic Adjustment
In a “closed loop system” with automatic control this interaction is called ‘feedback”,
Feedback from the controlled load is sent to a “comparator”,
A comparator compares the feedback to a reference signal or standard to determine what action should occur next.
LS 5-3

13. Control Systems Digital Control Systems
Digital (numeric) instructions are supplied by variations in pressure, temperature, or electric current.
These instructions change into a series of on/off electrical signals.
These electrical signals are processed by a computer and directed to the appropriate subsystem.

14. Control Systems Rotary Motion Systems
Electric motors convert electrial energy to mechanical motion in the form of rotary motion.
The rotary motion produces “torque”,
The amount of torque produced is determined by the size of rotary motion (motor),

15. DC Motor Parts
DC powered motors are used when speed control is a critical factor.
Listed below are the basic parts of a dc motor:
LS 5-4

16. Servomotor is used to achieve a precise degree of rotary motion,
Contains no brushes, commutators, or slip rings,
Is comprised of a rotor and stator assembly,
LS 5-9
(Adept)

17. Servo System
Servo Systems are machines that change the position of speed of a mechanical object.
Positioning applications include,
Numerical control machinery,
Process control machinery,
Robotic systems,
LS 5-8

18. DC Stepping Motor
Nearly all high-power servomechanisms use dc stepping motors,
Dc stepping motors are used to change electrical pulses into rotary motion,
They are more efficient than the servomotor,
They develop more torque than the servomotor,
LS 5-11
(Superior Electric Co.)

19. Overload Protection
End effector control on industrial robots must have some protection against overload.
Breakaway devices
“Mechanical fuses” are pins or tubes that break or buckle under extreme stress (torque),
“Detents” are two or more elements held in position by spring- loaded mechanisms that move from their original position when placed under stress, and remove or disconnect the power source,
“Pre-loaded springs” may also be used to prevent overload by releasing the spring and the end effector breaks away from the work area.