unit 57: mechatronic system - free study · the various types of actuators likely to be used in...

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Unit 57: Mechatronic System

Unit code: F/601/1416 QCF level: 4 Credit value: 15

OUTCOME 3

TUTORIAL 1 - SYSTEM DESIGN

3 Be able to produce a specification for a mechatronic system or mechatronic product

Standards: standards e.g. appropriate British, European and international standards. Required sensor

attributes: phenomena being sensed; interaction of variables and removal of undesired changes;

proximity of sensor to measurand; invasiveness of the measurement and measurand; signal form;

ergonomic and economic factors

Actuator and sensor technologies: selection of suitable sensor and actuator technologies for

mechatronic systems and mechatronic products

Controllers: selection of appropriate computer control hardware for mechatronic systems and

mechatronic products e.g. microprocessor, PLC, PC-based, PlC, embedded controllers

Pictures used in this tutorial are from various sources and may be copyright protected. Contact

[email protected] if this causes any problems.

Assessment of this outcome is best done with a suitable assignment.

CONTENTS

1. Introduction

2. Standards

3. Sensor Attributes

Passive or Active.

Analogue or Digital

Size

Proximity to Measurand

Temperature

Speed of Rotation

Proximity Detector

Speed of Response

Pressure Sensors

Self Calibration

Choosing a sensor

4. Actuators Choice of Technology

Hydraulic

Pneumatic

Electric Motors And Actuators

Other Actuator Designs

5. Design and Programming Hardware and

Software.

Control Hardware

Peripheral Interface Controllers

(Pics)

Software

Plc Simulators

6. Case Study - A Gyrobot

mailto:[email protected]


1. INTRODUCTION

Taken at face value, this outcome appears to require a student to have a wide range of detailed knowledge of

all the engineering disciplines covered by mechatronics. In reality a mechatronic design is likely to be

created by a team from different disciplines working together but all having a good understanding of the

other disciplines. The learning outcomes required are listed below. It has to be assumed that students have a

good knowledge of Mechanical Engineering, Electrical/Electronic Engineering, Fluid Power and

Programming Techniques. This tutorial can only provide a broad guide to show how you might achieve

them.

Learning Outcomes for Outcome 3

3.1 produce a specification for a mechatronic system to meet current British Standards

3.2 select suitable sensor and actuator technologies for a mechatronic system

3.3 specify appropriate computer control hardware for a mechatronic system

2. STANDARDS

The importance of international standards in each discipline should already be known to you. Very little

information will be found if you search for international standards specifically for Mechatronics but some

that are relevant are mentioned later in the tutorial. Standards are important in the design process to ensure

that:

Components fit and match each other

Examples: shafts, couplings, flanges, plugs, sockets, cables, pipes and so on.

Components perform correctly as predicted

Examples: speed, torques, force, strength, insulation, reliability and so on.

Electronic systems communicate with each other correctly

Examples: Digital and analogue protocols, signal standards, programming and so on.

Drawings, circuits, block diagrams, flow charts and so on are understood by every one by

conforming to the same standard.

Designs and circuits produced in different software suites can be exported to other software suites,

e.g. importing mechanical 3D models into other programmes to analyse the stress and dynamics.

Designs of the mechanical, electronic and control systems can be exported into robots, PLCs, PICS

and NC Machines (for making parts).

The standards covering all these are many. The main body for international standards is the ISO

(International Standards Organisation), the IEC (International Electrotechnical Commission) and the ITU

(International Telecommunication Unit). ISO and IEC have formed joint committees to develop standards

and terminology in the areas of electrical, electronic and related technologies. The three organisations

together comprise the WSC (World Standards Cooperation) alliance. National standards organisations

usually comply with the international organisations. Here is a list.

BIS India KATS Korea (Republic)

BSN Indonesia NEN Netherlands

ABNT Brazil SABS South Africa

AENOR Spain SAC China

AFNOR France SCC Canada

ANSI U.S. SIS Sweden

BSI U.K. SFS Finland

DGN Mexico SN Norway

DIN Germany SNV Switzerland

IRAM Argentina SNZ New Zealand

BSJ Jamaica UNI Italy

ICONTEC Colombia SAI Australia

ILNAS Luxembourg Sirim Malaysia

JISC Japan


3. SENSOR ATTRIBUTES

Outcome 2 covered the basic types and operating principles of various sensors. The student needs to be

knowledgeable about all aspects of sensors in order to choose and specify appropriate sensors for the design.

Here is a reminder of what you should know from outcome 2.

Measurand: things to be measured Basic principles:

o Movement and angle

o Velocity and acceleration

o Direction and location

o Force, torque, and pressure

o Proximity and contact (touch)

o Flow

o Viscosity

o Density

o Temperature

o Light level

o Sound

o Voltage, current

o Magnetism

o Frequency

o Dimensions

o Hardness

o Acidity (pH)

o Weight, volume

o Humidity

o and many more

o Resistive

o Capacitive

o Inductive

o Ultrasonic

o Piezoelectric

o Piezoresistive

o Light

o Radiation, Infra-red, X-ray

o Smart material sensors and

more

Other attributes to be considered are:

Passive or Active.

Passive sensors require no external power (e.g. some thermometers and light cell)

Active sensors require external power source (e.g. Strain gauge).

Analogue or Digital

Analogue sensors produce continuous signals such as a current (e.g. 4 - 20 mA standard) or air

pressure (e.g. 0.2 - 1 bar standard).

Digital sensors produce signals as binary numbers. This can be inherent in the design but normally

requires an Analogue to Digital converter (ADC). You might consider sensors with simple on or off

action as digital (e.g. proximity detectors).

Size

In many mechatronic designs it is advantageous to use very small sensors that can be integrated into a

circuit or structure. These are micro- and nano-sensors. They are very useful for building compact systems

with built in signal processing (such as ADC) and automatic calibration which might need a built-in micro

actuator. In this context you come across the terms MEMS which means Micro-Electro-Mechanical

Systems. This is a technology defined as miniaturized mechanical and electro-mechanical elements that are

made using the techniques of micro-fabrication.

1 2 3

1. A tilt sensor module that provides a digital level output if tilted beyond a preset level. Typically these are

used in games controllers whilst larger versions are used in vehicles such as measuring the pitch and roll

of a ship.

2. A flow cytometer widely used for analysing microscopic particles such as cells and bacteria and they are

used in medicine, life sciences and environmental metrology.

3. A Micro-mechanical accelerometer measurement system on a single monolithic IC. Typical uses are

vibration detection, game controllers, robots or anywhere you need to obtain motion-sensing &

orientation information.


Proximity to Measurand

The type of sensor is often dictated by the distance to the target (measurand) and its obtrusiveness to the

measurand. Here are some examples to explain it.

Temperature

Consider a sensor for measuring very hot temperatures. This might

destroy the sensor unless it is protected and this will make it slow

to respond (e.g. a thermocouple in a ceramic sheath pictured).

A solution would be an optical pyrometer typically as shown. This can be sited some

distance from the target and have a response time of typically 6 ms.

Speed of Rotation

The speed of rotation can be measured in various ways. Some tachometers need to be attached to the

rotating body. Others have to be placed very close and some not close at all.

1 2 3

1 - Motor with attached analogue tachometer.

2 - Hall Effect Tachometer - the sensor has to be close to the rotating body and operated by changes in

magnetic field.

3 - Optical tachometer sensor head can be placed up to 1 m from the target and works on reflected light

pulses.

Proximity Detector

Proximity detectors have a wide range of applications and detect if an object is present or not.

1 2 3 4 5 6

1 - A magnetic type sensor that fits on the outside of a pneumatic cylinder and is activated when the piston

inside passes it. Typically used to trigger signals to a controller and activate the next action.

2 - A magnetic type typically used to detect a hydraulic clamping cylinder has completed its action.

3 - An optical type on a chip. Typical uses are: to disable the touch-screen on a cell phone, to enable a

speakerphone automatically, to operate a menu pop-up automatically and to sense when someone

places their eye to the viewer of a digital camera.

4 - An optical type for sensing objects from some distance such as items on a conveyor.

5 - A capacitive type that detects materials a magnetic type will not.

6 - An ultrasonic proximity detector that works up to 6 metre from the target. It has advantages over other

types.


Speed of Response

All sensors have a time lag between a change in the measurand and a change in the output. The section on

temperature sensors mentioned this. Response Time is often defined as the time for the incremental change

in the output to go from 10% to 90% of its final value when subjected to a sudden change.

The response of the sensor has to be appropriate for the task. Most sensors based on electrical technology

are fast. Sensors, for example, used in combustion engine management systems have to be fast in order to

make the engine run properly. Here are some examples.

Pressure Sensors

1 2 3

1. Pressure sensor with a rise time of <3 μs for measuring fast pressure rises in shock waves.

2. Manifold Absolute Pressure sensor (MAPS) typically have a response time of 1 ms. They are built on a

chip that puts out a voltage proportional to engine vacuum, from zero to 5 volts. The computer uses the

voltage to decide if the throttle is open and how far, so it can adjust the fuel mixture.

3. A pressure sensor used for barometric pressure measurement does not need to be fast and this one has a

rise time of < 100 ms.

Self Calibration

Measurement systems are prone to errors over an operating life time due to drift. The zero point might need

to be reset and the gain adjusted. Some sensors are able to automatically calibrate/recalibrate themselves.

This can be useful when unexpected disturbances upset them. The system used might be a software solution

or it might involve moving the sensor to a calibration point.

1 2 3

1. Auto-calibrating line sensor for detecting lines 1cm to 3cm wide and determining dark colour or bright

colour line. With 1 press, it will start "recognizing" the surface under it, calibrating the threshold between

dark and bright. it takes 4 to 5 seconds only. After that, it is done, being stored in internal non volatile

memory.

2. CO2 sensor for use in biological or scientific applications. It is capable of performing a complete function

check of the sensor module.

3. A board mounting differential pressure sensor that enables a designer to use an algorithm to set the

compensation, calibration, and amplification while allowing the flexibility of self-calibration.

Choosing a Sensor:

Determine the variable to be measured

Determine the range over which it needs to be measured

Determine the speed of response needed from the sensor (time lag)

Bearing in mind the electronic systems used, decide whether you need analogue or digital outputs

Have a good idea of the size limitations and physical attributes needed to assemble and integrate the

sensor

Decide the proximity of the sensor to the target being measured.

Consider the energy requirements for the sensor.


4. ACTUATOR CHOICE OF TECHNOLOGY

The various types of actuators likely to be used in mechatronics were covered in outcome 2 tutorial 3. These

were either Electric or Fluid Power (hydraulics and pneumatics). Usually the choice is fairly obvious for the

tasks required of the system but sometimes the decision needs more consideration. The main attributes of

the actuators that need to be considered are:

The size of the operating forces and torques

The operating environment

Linear or rotational movement?

The energy source

Speed of response and motion

The amount of movement needed

The degree of precision needed

The method of control and monitoring

Hydraulic ADVANTAGES

High force and torque

High power to weight ratio

Linear and rotational actuators

High precision

Good low speed characteristics

Safe when the actuator jams (stalls)

Good in harsh environments

DISADVANTAGES

Relatively expensive

Requires a pumped fluid supply

Requires rigid and flexible high pressure

supply pipes and low pressure return pipes

Motion relatively slow but response is fast

Fluid might be a hazard and messy

Requires associated valves to control the

motion

Pumping system runs continuously and

energy is used even when actuator is not in

use.

Hydraulics is chosen for applications needing high pressure and firm precise motion. Examples are

industrial robots, aircraft systems, marine uses (e.g. stabiliser systems), heavy duty precision machining,

large vehicles and so on. They are the only choice for use under water because designing and making sealed

electric motors is costly and requires substantial engineering. More examples are shown below.

1 2 3

1. Typical hydraulic power Pack

2. A small hydraulic motor 45 mm diameter and produces 17 N m torque.

3. A heavy duty hydraulic motor producing 1785 N m torque

1 2 3 4

1. Hydraulic cylinder with stroke of 7 mm and thrust of 1.7 kN

2. Hydraulic cylinder for marine applications capable of a 24 metre stroke

3. Heavy duty industrial robot with hydraulic actuators

4. A rotary hydraulic actuator for robot joints


Pneumatic

ADVANTAGES

Medium and low force and torque

Linear and rotational actuators

High relative speed

Micro actuators available for small

applications

Do not need return pipes as used air is vented

Relatively cheap

Safe when the actuator is jammed (stalls)

Clean and easy to maintain

Safe in explosive environments (APEX

compliant)

Motors are light and compact compared to

electric motor.

Motors are robust and highly durable under

extreme operational conditions

Rodless cylinders possible with pneumatics

only

DISADVANTAGES

Time delay at start of motion due to

compressibility of the air.

Precision more difficult to obtain

Requires a compressed air source, usually a

ring main

Dangerous at high pressure

Requires associated valves to control the

motion

Only safe at low pressure

Air compressor runs continuously so energy

is used even when the actuator is not in use.

Air leaks tend to be ignored and this is costly

Pneumatic actuators are chosen where high pressure systems are not needed and precise motion is not

needed. They are widely used in production lines for moving things, diverting things, opening and closing

things and so on. Air is the choice for tools such as drills, grinders, riveters and so on because they are safe

when they jam. Electric actuators are expensive if they are manufactured to work in dangerous

environments such as dusty or other explosive atmospheres. Pneumatics is the best choice as they are

cheaper and safe. Here are some examples.

1 2 3 4

1. Pick and place robot not requiring high precision

2. Deburring tools for use on robot arms

3. Suction Pads for lifting light objects

4. Clamping Cylinder

1 2 3 4

1. Air motor with gears for driving many types of machines

2. Air motor for driving a conveyor belt system

3. Stainless steel motor for use in acidic environment

4. Milling robot for drain restoration with air motor


Electric Motors And Actuators

ADVANTAGES

Very versatile ranging from very large to

very small

Electric power sources are can be mains

supply or battery

Wide range of operating characteristics some

with precise motion control

Easiest to integrate into compact systems

Control equations usually simpler as the

system is more linear

Energy is only used when the actuator is in

motion

Clean and relatively easy to connect

DISADVANTAGES

Heavy duty motors are bulky

Mechanical motion converters often needed

(e.g. to produce linear motion)

Burn out if the motor stalls

Become expensive if they need protection

from harsh environment e.g. salty damp

atmosphere

Hazards associated with electricity (e.g.

sparking of fires and explosions in certain

environments)

For demanding applications that require

extremely high torque, electric motors

become too costly and too bulky because of

the large number of windings needed

Actuators are widely used in systems where the flow of a fluid through a pipe needs to be controlled and

adjusted. This might involve changing from open to closed or accurate positioning of the valve spindle.

Here are some examples.

1 2 3

1. Electric Actuator for operating flow control valves

2. Electrically operated valve

3. Linear electric actuator with many uses similar to a pneumatic cylinder.

Electric motors have been described in more detail in outcome 2. They are used for many applications from

very large to very small. Here are some examples.

1 2 3

1. Electrically powered drone

2. Robot arm with electric servo motors

3. Large DC drive for rolling mill


Other Actuator Designs

Ultrasonic Motor

Ultrasonic Motor (USM) harness ultrasonic oscillation from a piezoelectric element. They are mainly used

in camera mechanisms to focus the lens. This technology makes focusing precise, virtually noiseless and

incredibly quick – some lenses focusing literally faster than the human eye. The picture below shows the

motor and gearing used in a camera.

Electromechanical Solenoids

These devices are basically electromagnets which when energised cause the iron core to move. They are

used to produce limited linear movement and are ideal for operating mechanisms that only need to operate

between two limits. They are digital devices either on or off and so relatively easy to use in a control

system. Typical uses are:

Electrically operated fluid control valves (hydraulic and pneumatic valves)

Gaming devices such as a pin ball machine

Dot matrix printers

Fuel Injectors

Starter motor switch

Electrical relays

1 2 3 4

1. Engine Solenoids

2. Solenoid operated valve

3. Solenoid operated pneumatic valve

4. Solenoid operated fuel injector

Muscle Wire

This is a smart metal that "remembers" its original shape and when deformed it

will return to its previous shape when heated. Basically a wire device can be

made to bend or contract and this has applications for things like robot hands

where the fingers can be made to move. It is basically a solid state device that

can produce linear movement in response to an electric current.


Rodless And Double Rod Designs

Rodless cylinders are only possible with pneumatic cylinders. You will have to look elsewhere for details of

the operating principle but basically the moving piston inside is attached to a carriage on the outside which

slides back and forth along the cylinder. These are very versatile actuator that can be used to operate many

kinds of mechanism such as picking and placing with a suction cup.

Rodless Pneumatic Cylinder and a pick and place robot using them

Double rod cylinders have the same kind of versatility where the rod is clamped and the cylinder body

moves. These are used in hydraulics and pneumatics and are often used to move platforms.

Double rod cylinders pneumatic left, hydraulic right.


5. DESIGN and PROGRAMMING HARDWARE and SOFTWARE

In this modern era it is almost unthinkable that some of the most complex mechatronic systems can be

designed and then controlled without the use of advanced software programmes. Software is used to:

produce a 3D design of the mechanical system

design and model the different control system algorithms

design the electronic and/or fluid power circuits

simulate and test the overall model for performance

identify and select electronic components for the real system

After this stage you need to:

identify and specify real sensors and actuators that meet the requirements

identify and specify mechanical components

build and test prototype

One computer programme that does all this is known as ADAMS (Automatic Dynamic Analysis of

Mechanical Systems) from MSC Software. This is a Multi-Body Dynamics (MBD) simulation programme.

With this you can study the dynamics of moving parts and how loads and forces are distributed throughout

mechanical systems.

This programme also enables you to merge your mechanical design with control and electronic designs

created on other software packages such as MATLAB® and Easy5®.

Adams/Mechatronics is a plug-in to Adams which can be used to easily incorporate control systems into

mechanical models. Adams/Mechatronics has been developed based on the Adams/Control functionality

and contains modelling elements which transfer information to/from the control system.

Visit this web site to see simulations of complex systems like the moon rover.

http://www.mscsoftware.com/product/adams

Many other suites of software are available for designing such as:

Circuit Wizard http://www.new-wave-concepts.com/ed/circuit.html

Genie Design Studio http://www.genieonline.com/

Mplabs

Automation Studio™

Multiprog

You will find more on this in the PLC module unit 22 outcome 4.

http://www.mscsoftware.com/product/adams

http://www.new-wave-concepts.com/ed/circuit.html

http://www.genieonline.com/

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en019469&part=SW007002


Control Hardware

When deciding what kind of electronic system to use for controlling the system you should consider:

Is the system compact enough to integrate the electronics within the main electronic circuit such as

with a peripheral interface controller (PIC)?

Is the system robust and suited to being controlled by a unit such as a programmable Logic

Controller (PLC)?

Peripheral Interface Controllers (PICs)

These are advanced microcontrollers developed by microchip technologies. They are sometimes called a

computer on a single chip but might be best thought of as a PLC on a single chip. The programme to

produce the required control function is developed and loaded into the chip. The chip is then embedded in a

machine or device to control it. Shown is a chip and test board to enable it to be programmed and tested.

Examples of machines that use them are:

Cameras/Camcorders

TV controllers

DVD Players

Microwave Ovens

Printers/Scanners

Keyboards and Mouse

Modems

Motor cars

Medical devices

Toys

Robots

Mobile Radios/communication devices

Vending Machines

….. and many more

The largest single use for microcontrollers is the automobile industry where they are widely used for

controlling engines and power controls in automobiles. In industry they are usually set up to carry out a

dedicated control function in a variety of processing/manufacturing systems. They are expected to be

durable and to work for a long time. They are used widely to control individual items like conveyor belts

largely independent of the main system but linked into the overall control system. They are embedded in

some instruments to perform on the spot control and are interrogated by the main controller.


Software

The following describes some of the software available for programming your control system

Circuit Wizard http://www.new-wave-concepts.com/ed/circuit.html

You need a computer to run this software. It allows you to program a PIC microcontroller circuit. The

computer will need a serial port or a USB port. This is used to connect the computer to the microcontroller

circuit. For educational use Genie Design Studio is a version of the same software.

Genie Design Studio http://www.genieonline.com/

This is software for programming GENIE microcontrollers. Its powerful language and highly graphical

interface make the whole process of developing electronics-based projects quick and easy. You construct a

flow chart by dragging and dropping commands from the library.

By double clicking on the box you can set labels, timers and input/output designations available on the

selected chip. This replaces numerous lines of text programming code and means that a program can be

written quite quickly, with fewer mistakes. It is then simulated on the screen to check that it works. The

program is finally downloaded to a GENIE microcontroller. The circuit board design is also shown and if a

suitable socket is added to connect it to the computer, the chip can be programmed on the board. The

following shows a flow chart and circuit from the screen. The circuit can be tested by simulating on the

computer.

http://www.new-wave-concepts.com/ed/circuit.html

http://www.genieonline.com/


MPLABS

This is free very advanced programming/debugging software for a wide range of Microchip’s more than 800

8-bit, 16-bit and 32-bit MCUs and digital signal controllers, and memory devices. The screen dump below

shows that you need to be a serious programmer to use this.

See also PICkit™ 3 which is a kit to enable a chip content to be examines and debugged.

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en538

340&redirects=pickit3

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en019469&part=SW007002

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en538340&redirects=pickit3

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en538340&redirects=pickit3


PLC Simulators

It is usually best to adopt any software and simulator hardware recommended by the manufacturer of the

PLC chosen but there are graphic programmes that enable you to design and test circuits and then convert

them into a form suited for a given PLC.

Automation Studio™

This is a professional suite of programmes allowing the construction of electric, electronic, pneumatic and

hydraulic circuits (Mechatronics) and their associated PLC control circuit in Ladder programming or

Grafcet/SFC programming. Automation Studio™ can import SFC/Grafcet codes either in XML or in

Cadepa™ software format. It also allows you to export SFC/Grafcet into Siemens™ S7 PLC and XML

format. The circuit is simulated on screen and transferred to the PLC through an interface. It can also be

used to control hardware directly through a suitable interface making the computer into a PLC. The diagram

shows a circuit and SFC programme.


Mitsubishi/Melsec

With the appropriate hardware to connect the

PLC to the computer, programmes can be

created, tested, simulated, downloaded or

uploaded from the PLC and the PLC can be

monitored when running.

The diagram below shows a typical programme

designed with the software.


Rslogix 500 Software

The RSLogix software is a design studio using ladder logic programme compliant to IEC-1131.

It is designed to be used for the Allen-Bradley SLC 500 and Rockwell MicroLogix family of processors.

Multiprog

This is a programming suite from KW Software. Details may be found at this link.

https://www.kw-software.com/en/iec-61131-control/programming-systems/multiprog-5

This software allows programmes to be produced using any of the five programming systems defined in the

international standard IEC 61131 and explained in outcome 3. Apart from the actual programming function,

a modern programming system provides a broad range of intelligent additional functions, which support

programmers in developing, testing, and commissioning their application. It takes care of the project

management and helps with the management of fieldbuses, networks and peripheral components.

http://www.rockwellautomation.com/rockwellsoftware/design/rslogix500/

https://www.kw-software.com/en/iec-61131-control/programming-systems/multiprog-5


CASE STUDY - A GYROBOT

This is based on extracts from a published project to design and test a GYROBOT. You will find the full

article at this web link. www.s2is.org/issues/v2/n2/papers/paper1.pdf

A Gyrobot is a single wheeled vehicle that must roll in either direction and also steer left or right.

Propulsion is by turning the axle with the drive motor. Control is by a radio link.

Basis of the Design

The wheel is basically a hollow shell with a tyre around it. This is modelled with the Adams software or

imported into Adams from other programmes such as Autocad® or SolidWorks

®. The wheel will be driven

by rotating the axle with a motor and drive belt mounted on a platform. The platform will be supported on

the axle and kept roughly horizontal by the suspended weights below it. Rotating the axle will also try and

rotate the platform the opposite way by reaction torque so this is applied by the suspended weights.

A flywheel is suspended below the platform and made to spin by the spin motor. The speed will be

controllable between 1000 and 7000 rev/min. The flywheel keeps the wheel balanced through gyroscopic

torque. The flywheel is mounted on a 2 axis gimbal. If it is tilted by the tilt motor, gyroscopic torque makes

the wheel turn about the vertical axis and it will lean into the turn through gyroscopic torque produced on

the wheel but only if it is revolving (like leaning over on a bicycle).

The electronic module will contain the battery pack, radio link, programming system and the controller. The

controller will control the motors based on the control programme.

Produce a 3D model of the system (outline design shown above).

Import it into the Adams programme

Produce a control model for controlling the motor speeds

Test the computer model by running the flywheel and drive motor and operating the tilt motor. If

necessary make adjustments to the flywheel mass or any other corrections to the design.

When a satisfactory performance has been obtained then a detailed design must be produced. The

component parts must be specified, obtained and assembled. The Gyrobot should be ready to go and it

should work first time if all has been done according to plan. Put this way it all seems simple but when

producing the detailed design there is a lot to be done.

You will need appropriate types of motors to produce the required speeds and torques and this may require

some form of speed reduction or increase e.g. with drive belts and pulleys or built in gears. The tilt motor in

particular will only have to produce a small rotation so probably a stepper motor or other servo motor.

The electronics would have to be compact so probably a PIC system would be best. If feedback is to be used

in the control system (closed loop system) then appropriate sensors would be needed to measure the angles

and speeds.

http://www.s2is.org/issues/v2/n2/papers/paper1.pdf


SELF ASSESSMENT EXERCISE

The Gyrobot outlined is to be steered remotely and its speed varied remotely.

List the things that need to be sensed.

Suggest the best type of sensor for each application giving your reasons.

List the actuators that are needed.

Suggest the best actuators for each application and give your reasons.

Outline a control programme using any suitable graphics.

Outline an electronic design using any suitable graphics.

Describe the best hardware for implementing the control.

unit 57: mechatronic system - free study · the various types of actuators likely to be used in...

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