The simulation of the MAHO-700S milling machine by the useof the software package roboticsCitation for published version (APA):Vernooij, J. W. G. (1991). The simulation of the MAHO-700S milling machine by the use of the software packagerobotics. (TH Eindhoven. Afd. Werktuigbouwkunde, Vakgroep Produktietechnologie : WPB; Vol. WPA1088).Eindhoven: Technische Universiteit Eindhoven.

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REPORT

Subject: The simulation of the MAHO-700S

milling machine by the use of the

software package Robotics.

John Vernooij

WPA report 1088

June 1991

Student identity number: 242960

Supervisory team:

Date:

Prof.Dr.lr. A.C.H. van der Wolf

Ir. J.A.W. Hijink

Ing. J.J.M. Schrauwen

F.J.G. Soers

12 June 1991

SUMMARY

In the scope of the automation project FALC, the division of Production Engineering and Automation

(YVPA) of the Eindhoven University of Technology has procured the software system Robotics of the

company McDonnell Douglas. The purpose is to determine if required motions can be simulated by a

robot, If off-line programming can be accomplished and if estimated cycle times can be met.

The subject of this work is to evaluate whether Robotics can be used for the five-axis simulation of

the available MAHO-700S milling machine. Robotics is divided into five modules of which PLACE and

BUILD, together with UNIGRAPHICS II, describe the robot geometry and motion.

During this project the restrictions for creating a device have been examined as well as the way

desired motions can be performed. The geometrical parts can be designed with UNIGRAPHICS II

and transformed to a motion device by BUILD. The inverse kinematics. which convert all orientations

and positions into joint values of a device. proved not to work properly In case of a four axis device.

However, the desired joint positions can be reached. Therefore a simulation had to be found using

forward kinematics. A geometrical model of a fIVe-axis milling machine is developed which Is able to

reach a predefined set of joint values. To control this a sequence is written which describes the

motion simulation for a five axis machined product.

To perform the simulation a spatial tpoint is created which is the orientation point for both created

devices. With respect to this tpolnt NC-information for an existing product has been entered in a

sequence. This sequence controls the motion simulation. All joint zero values have been added up

with the joint values in the NC-sentence. The toolpath entered in the PLACE sequence has been

done manual. It is recommended to generate a tool which can automatically translate NC-information

to PLACE-sequence commands.

Finally the collision detection mode has been examined in order to find the regulations for a collision

detection simulation.

TABLE OF CONTENTS

Summary

Page

1. Preface 1

2. Problem description

2.1

2.2

2.32.4

The MAHO-700S milling machine

The Robotic system

The CAD/CAM system

The heart of the problem

2

3

3

4

3. Results

3.1

3.2

3.3

3.4

3.5

4.

5.

The simulation configuration

The alignment between the 'goto tpolnt' and

'working tpoint'

Orientation of the product zero point

The simulation

Collision detection

Conclusions and recommendations

Literature

5

7

7

8

9

10

11

Appendices

1.

2.

3.

4.

5.6.

The MAHO-700S milling machine

Architecture of Robotics

PLACE

BUILD

Instructions for a succeedeing student

BUILD-files of devices 1 and 2

12

15

17

25

31

32

1. PREFACE

CAD, Computer Aided Design, Is the computer supported design of products in which specific

geometrical information is digitally stored. The design can be performed in 2-, 2Yo! and 3 dimensions.

Within a 3 dimensional product design a distinction is made into three technics of modelling:

wireframe, surface and solid modelling.

CAM, Computer Aided Manufacturing, is computer supported manufacturing of products. Within the

stretch of manufacturing a distinction can be made into two specific fields:

a) The computer supported generation of product informa­

tion for NC-machines, the NC-programme. This kind of

activities is executed by a CAM-system.

b) The computer supported execution of this information

within the NC-machine, which is being performed by the

control system of the machine.

In the scope of the automation project FALC, the division of Production Engineering and Automation

has procured the software system Robotics. The purpose is to determine if required motions can be

simulated by a robot, if off-line programming can be accomplished and if estimated cycle times can

be met.

Right now a connection between the CAD/CAM system and the MAHO-700S milling machine without

any intervention of paper has been achieved. On an available PC a test can be performed of NC­

programmes by means of a simulation. However only simulations up to 3 Yo! axis can be executed.

Owing to the complexity of NC-fiIes for 5-axis processing, collisions and failures are hard to

recognize.

The purpose of this work is to look if a 5-axis simulation can be performed with the available

software. The installed Robotic-system of McDonnell Douglas is being examined on its suitability for

five-axis simulation.

2. PROBLEM DESCRIPTION

2.1. The MAHQ-700S

The MAHO-700S milling machine is a universal machiningcenter with an automatically changing of

the head spindle and tool. The system Is supplied with a fIVe-axis path control system: the CNC 432

of Philips. For technical data see appendix 1.

The machine is controlled by a NC-programme which includes all information necessary to transform

the rough material Into the desired product. The control unit reading this programme, translates it to

mechanical movementS of the machine.

The NC-programme consists of sentences. Each sentence is constructed of words. Each word is a

machine instruction and contains an adresscapital and a number. The capital defines the kind of

information. An example of a NC-sentence is:

NIO GOI X20 Y35 F200 51000 M3

number of sentence is 10 ~path conditionpath informationfeed rate 200 rom/minnumber of revolutions 1000 r.p.m.help mode: spindle spins clock wise

The MAHO contains a rectangular coordinate system (see fig.1). The tool performs its relative motion

with respect to the milling table In Z-direction. The translations along the X- and Y-axIs. and the

rotations about the A- and B-axis are being performed by the milling table. containing the product,

with respect to the tool.

2

figure 1: The coordinate system of the MAHO 700S.

2.2. The Robotic system

Robotics is an industrial simulation and off-line programming system. The software package is suited

for three purposes: - Simulation of robot motion

- Off-line programming

- Ergonomy simulation

Robotics contains five modules: PLACE, BUILD, ADJUST, COMMAND and CTA. For an architecture

of the system see appendix 2.

Only PLACE and BUILD are used for the simulation in this project. For a description of PLACE and

BUILD see appendices 3 and 4.

In this project the Robotics release 7.0 is used.

2.3. The CAD/CAM system

The CAD/CAM-system available at the division WPA has been developed by the aircraft company

McDonnell Douglas. The system can be described as follows:

3

CADCLS- Pre CL- NC-

• : postprocessorI

CAM ~ Processor Ifile file file

I FEATURES

figure 2: The realization of a Nt-file

The input of the system is separated into 3 parts:

- The CAD-data. The design on the CAD-system can be performed 3-dimensional. Three

types of modelling are distinguished: wireframe, surface and solid modelling.

The CAM data. As It is an Integrated CAD/CAM system the CAD-data can directly be

retrieved within the CAM-module.

The Feature data. This part of the CAD/CAM system has been developed at the division

WPA The creation of geometry is integrated with the generation of tooling

information. After having created a product not only the geometry is fixed but the

tooling information as well.

The pre-processor transforms the CLS-file to the CL-file. In this all simulation commands are being

removed. With the help of a post-processor the machine-independent CL-file can be transformed to a

machine-specific NC-file.

2.4. The heart of the problem

A connection between the CAD/CAM system UG II and the MAHO-700S milling machine without any

Intervention of paper was achieved In 1990 at the division WPA Owing to the complexity of

5-axis processing a simulation to detect collisions and failures is desired. The combination of UG II

with PLACE and BUILD should be used to define the machine geometry, inverse- and forward

kinematics and to perform a simulation. A CLS-file describes the toolpath of the processing of a

prodUCt. To achieve a full simulation the machine independent CLS-file has to be adapted to the

MAHO by adding machine specific information.

4

3. RESULTS

3.1. The simulation configuration.

Device 1

Device 2

figure 3: The simulated workcell.

5

The MAHO-700S milling machine uses 5 axis, the translation axis X, Y and Z and the rotation axis A

and B. This can be interpreted two chains connected to a fixed base. like a floor in a plant. The

chain which contains the machining tool derives its motion along the Z-axis. The second chain,

containing the product performs translations in X- and Y direction and rotations over the axis A and

B. Therefore. during this simulation a cell is created by combining two devices describing the five

degrees of freedom. Each device is constructed of frames. Device 1 performs Its motion in Z­

direction and device 2 moves over the four axis left (see fig.3). For the BUILD flies see appendix 6.

The concept of a connection tree is used to describe the connectivity relationships between the

frames within a cell. ~hen a frame Is connected to another frame, the connected frame is called a

son frame, and the frame that the son is connected to is called the frame's father. Only the WORLD

frame has no father. Furthermore when a frame moves all descendents will move and no ancestors

of that frame will move. The construction of this simulation model agrees with the real configuration

of the MAHO-700S which in fact also can be seen as a construction of parts all translating or rotating

in just one direction. See fig.4 for the connection tree of the developed devices.

o WORLD

(Device 1)

1 FreesbO: porchcolumn

2 Freesb1 : Z-carriage

3 Freesb2 : None

(Device 2)

1 Freesta11 : Porchcolumn

2 Freesta10 : Y-carriage

3 Freestaf9 : X-carriage

4 FreestafS : turning table A

5 Freestaf7 : rotation table B

6 Fr~staf6 : None

figure 4: The connection tree of the two devices.

6

3.2. The alignment between the 'goto tpoint' and 'working tpoint'.

The configuration of the simulation model of the MAHO as explained In section 3.1 Is desired to

perform a motion. Therefore the restrictions within PLACE and the concepts PLACE uses will be

explained in this section.

To align a robot PLACE uses the concept of 'tpoints'. Tpoints are the positioning entities in a PLACE

cell. A tpoint fully describes six degrees of freedom in space. A tpoint always represents a position

and an orientation.

In order to come to a proper alignment between the two devices the working tpoints and the goto

tpoints should be attuned to one another. The working tpoint of a device is the tpolnt which is

directed to align with the goto tpoint after a goto tpoint command. A goto tpoint can be any position

in space which a device is desired to move to. When more goto tpoints are required to describe a

toolpath, a sequence of tpoints should be made.

PLACE does not require the working tpoint to be connected to the faceplate. The faceplate Is the

end link of device 2. Any tpoint within the working cell may be chosen to be the working tpoint of a

device. If the working tpoint is not connected to the faceplate the goto tpoint must be connected to

the faceplate or a frame that is descendent of the faceplate in the connection tree.

In case of the simulation of the MAHO it is desired to direct the tooltip of the milling machine to the

cutter positions of the product. The most realistic situation when using inverse kinematics is when

the CLS-file, which is in fact the goto tpoint sequence, is connected to the faceplate. The working

tpoint of device 1 can be its tip of the milling tool. The faceplate is desired to be directed to the tip of

the milling tool of device 1. Therefore the working tpoint of device 2 should be located along the

translation axis (z-axis) of device 1 and be connected to fatherframe wor1d. When a motion

simulation is performed the goto tpoint of device 2 (a tpoint connected to the faceplate) will be

directed to Its working tpoint along the z-axis and the goto tpoint of device 1 (also the tpoint

connected to the faceplate) will be directed to its working tpoint which is the tip of the milling tool.

The concept of alignment is necessary to direct the axis crosses of both devices to one another to

make sure that both orientations are the same. The setting of the working tpoint only needs to be

done one time to suit the model of the milling machine for simulations.

3.3. Orientation of the product zeropoint

A postprocessor has been developed at the division WPA which transforms the machine independent

CL-file to the machine specific Ne-file. It requires the zero-point of the product to be chosen at the

faceplate and in the center of the turning table. This because the product zero-point Is considered to

be the position of the B-axis. The link between the moving and the resting wor1d is in the center of

the A-axis. The NC-files are being generated with respect to this resting point. So the difference

between the zero-points of the machine and product with the use of this 5-axis postprocessor always

7

is: (X; Y; Z) = (0; 255,077; 0,03). In case no rotations are being corrected but only translations, a

movement of the product zero-point is not allowed. As a result of this the product always needs to

be aligned In both the X, Y, and Z directions.

In the developed model of the the MAHO an orientation tpoint connected to fatherframe world is

created along the translation axis of device 1. The joint values when reaching this position are

considered to be the zero values of the product. With respect to this tpoint desired toolpaths can be

defined by adding up joint values. In NG-programmes the same principle is used.

3.4. The iimulation

In this project the five-axis cell "freesbank" has been developed. The cell is composed of two

devices. Device 1 translates along the Z-axis, device 2 performs translations along the X- and Y-axis,

and rotations around the X- and Y axis (see fig.3).

The standard kinematics of the developed device 2 allow a motion to any joint position. When the

device is instructed to go to a predefined set of joints values, no alignment problem will occur.

However, when an arbitrary tpoint is created and connected to the faceplate and when both devices

are ordered to align their working tpolnt with the created goto tpoint. an alignment problem occurs.

This is due to the inverse kinematics which occasionally yield alignment problems when using

devices with less then six degrees of freedom. A tpoint created by three translations and two

rotations describes six degrees of freedom in space. Any device with less than six degrees of

freedom can therefore usually not align.

To this, PLACE offers a possibility to add joints to a similar device which will cause it to work

properly. The device with four degrees of freedom has now been extended to a device with six

degrees of freedom. PLACE computes the desired joints of the similar device and a coordinated

mapping file will map this joints on device 2 and remove the unwanted joints. When using this option

in case of device 2 this results in a core-dump. The research center of McDonnell Douglas in Paris

answered that this lack will be remedied in the Robotics version 8.1 which will be released in June

1991. Tpoints with three translational values and only one rotational value did not cause any

alignment problem.

The forward kinematics of both devices work properly. Any joint position in space within the limits of

the device can be reached. A tpoint has been created along the translation axis of device 1 which

can be reached by both devices. However, the simulation can only be performed for straight line

motion. A circular toolpath should be cutted into small straight pieces in order to perform to a

simulation.

All information to direct the devices to a specific set of joint positions is included in a sequence

which data in fact controls the simulation.

8

3.5. Collision detection

The collision detection may be split up into four parts:

1) Collisions which occur between the tip of the milling tool and the

faceplate. The geometry needs to be entered for an accurate model of

the MAHO.

2) Collisions which occur between the tip of the milling tool and the

clip. A library should be made containing all types of clips which

are available to the MAHO.

3) Collisions which occur between the arm of the Z-axe and the faceplate.

The joint limits should be entered in the accurate model.

4) Collisions which occur between the tip of the milling machine and the

product. Both machine specific data and the CLS-file should be entered.

How a collision test can be performed within PLACE is described in the PLACE-appendix.

9

4. CONCLUSIONS AND RECOMMENDATIONS

The Robotics software package has proved to be dedicated to perform simulations of robot devices.

Two ways to perlonn a motion simulation have been examined:

The inverse solution does not yield a desired result for a four axis device. An arbitrary tpoint

in space has usually six degrees of freedom. A four axis device combined with another

device can not align with tpoint of six degrees of freedom. A developed device with six

degrees of freedom had no difficulties with aligning.

The forward solution yield amazing pictures. A motion simulation with a model of the MAHO

can be controlled properly. In this. a tpoint in space has been created which serves as the

orientation point for both devices. Any toolpath can be defined with respect to this tpoint by

adding up joint values. In an NC-programme the same principle is used. It Is recommended

to develop a programmme to translate NC-sentences to PLACE-sequence infonnation.

To perfonn the simulation a spatial tpoint is created which is the orientation point for both created

devices. With respect to this tpoint NC-information for an existing product has been entered in a

sequence. This sequence controls the motion simulation. All joint zero values have been added up

with the joint values in the NC-sentence. The tooipath entered in the PLACE sequence has been

done manual. It is recommended to generate a tool which can automatically translate NC-infonnation

to PLACE-sequence commands. In Appendix 5 all instructions for a succeeding student to start the

simulation of an arbitrary chosen product have been summarised.

To make things more surveyable, some software should be written which takes into account the

substraction of rough material when a toolpath has been runned out. Also an indicator to detect

what kind of mistakes occur is desired.

The next Robotics version 8.1 which will be released in June 1991 contains several different NC­

machines in the user library which are supposed to perform a proper simulation.

10

5. UTERATURE

1. Molengraft G.J.G. van de, Programmeerhandleiding MAHO-700S. T.U. Eindhoven,

WPA rapport 0712, 1989.

2. Senden R., Realiseren van een CAD/CAM koppeling. T.U. Eindhoven, WPA rapport 0930,

1990.

3. Manual PLACE version 6.1, McDonnell Douglas Manufacturing & Engineering Systems

Company.

4. Manual BUILD version 6.1, McDonnell Douglas Manufacturing & Engineering Systems

Company.

11

APPENDIX The MAHo-700S milling machine

1

4

10

9

2

De MAHO 700 S

3

5

6

rIIL­II

8

7

,. Schuildeur rechlS2. Toegangsluik hydrauliek3. Toegangsluik venlielblok hydrauliek. pneumaliek4. Schulldeur voor5. Schulldeur link S6. Toegangsluik koelmiddelleidingen en gereedschapwisselaar7. Toegangsluik gereedschapmagazijn en cenlraalsmering8. Bedieningspaneel en beeldscherm9. Koelvloeislof reservoir, O. Verfichlmg, 1. Kanletbare rondtafel12. Kanlelbare vertikale kop

12

MAHOMH 700 SDe MH 7005 Is een universele frees en boormachlne mel een universele gereedschapwisselaar.voorzlen van een S-assige conlourbesturing. de CNC 432 van de firma Philips. Voor hef posllionerenIn de assen X, Y en Z beschikt de machine over lineaire meelsyslemen en voor de assen A en B overrota tie meetsystemen.

Technische gegevens:Machine bereik:

langsvertikaaldwarsrondlalelzwenkas

X-as 700mmV-as 500mmZ-as 600mmB-as n • 360 gr.A-as -20 lot +45 gr.

Hooldspil :aandrljving: regelbare wisselstroommolor met een vermogen van 10 kWtoerenrallenreeks: 20-6300 omw/mintoerentallen: trappeloos regelbaar binnen 4 reeksen.

Freesspilfen:automatisch weg Ie draaien verlikale freeskopgereedschapsconus ISO 40gereedschapsopspanning hydro-mechanisch

Aanzelbe"egingen:individuele gelijkstroomaandriJving. per as regelbaar.aanzelsnelheid in X. Y en Z: 1-4000 mmlmin

A en B-as: 1-3000 graden/min

IJIgang:X en Z-asYeasB-asA-as

12 mlmin10 mlmin150mw/min16 gr/sec

Meelsysleem:X. Y en Z-as:A en B-as:oplossend vermogen:

inkrementeel - Iineair.inkrementeel - roterend.X, Y en Z-as 0.001 mm.A en B-as 0.001 graad.

Gereedschap"isselaar:aanlal gereedschappen In hel magazijn: 36

Tafel:zwenk-rond·talel. diameter 520mm

Beslurlng:Philips CNC 432 contourbesturing mel beeldscherm

Ge"ichl:machine compleet ongeveer 8500 kg.

13

MAHOAKTJEHGESEUSCHAFT

ME:SSPROTOKO LL

M.-Typ: .....11~,tI...;....l.;;.....;;;tJ~~~'---_M.-Nr.: 77PS-S-

Bemerk.: _

°MaOversa tz:A-Achse Drehachse zuE-Achse Drehach~c

_++-_+ O.O]!) .

MAHO I q.Ob-~/37~O

AKTIENGESEllSCHAFT Jofi 700 S

I, HC-~~ - lRBEI'T'SRAtJ4~

II

15

APPENDIX 2 Architecture of ROBOTICS

OESICN 10---01 COMPONENT'SROBOTOESICN BUILD

CAD

ORArnNC WORKCELLI..AYOlTI'

TASKOESCRlmON

SIMULATION

TRANsunON

PLACE

COMMAND+TRANSLATOR

ADJUSTerA

CAUBRATION

OOWNLOADlNC 10

ROBOT CON'\~OLl.ER

Work cell

16

APPENDIX 3 PLACE

In this PLACE summary a system overview and a short manual of the main functions used in this

project are regarded. For the complete extend of the PLACE possibilities, see the PLACE manual.

System overview

PLACE, Positioner Layout And Cell Evaluator, is a software package designed to create, analyze and

modify robotic cells graphically through use of a high speed, vector refresh or rast~r colour graphics

display station. PLACE allows to determine If required motions can be accomplished by the robot

and if estimated cycle times can be met.

PLACE uses wireframe or solid graphic models to represent robots, equipment, workpleces, and

tooling within a cell. The user can position these graphics within a cell either Individually, as in the

case of a workpiece, or together, as in the case of a multi-segment robot.

PLACE uses the concept of a generalized tool tip called the WORKING TPOINT. The robot can be

commanded to a desired location in terms of this working tpoint. The system determines robot joint

angles.

The PLACE software displays equipment repositioning and robot motion trajectories at the robotics

design station. Visual collision detection is also available with PLACE. You can change views of the

cell easily or use the zoom feature. With these viewing capabilities collision between the different

items within a cell can be identified qUickly and avoided.

After the cell has been laid out, various data can be requested from PLACE. Any relationship

between two tpoints, two frames, or between a tpoint and a frame is readily accessible to the user.

Furthermore PLACE maintains a library of commercially available robots. Any robot in the library can

be requested for evaluation and robot motion analyzes. By using the BUILD programme the user can

also insert a new robot.

17

Short manual

Accessing PLACE

After you have turned on the system you will be asked to enter your username and password. To

enter PLACE pick:

> 22 Simulation/Robotics, Enter

> 2 Place, Enter

The PLACE main menu will appear (see fig. 6):

McOonnell Douglas PLACE bl....e 6.0Main Menu

1 Cell Edi~ing

2 Oevice Motion Control3 Hove Frames!Tpoints4 I/O and Variables5 Branching an~ Conditional Execu~ion

6 Sequence Editing and Control, View and Display ControlS Dimensional Analysis9 Collision Detection

10 File Management11 Time Con~rol

12 File Cell!Terminate

,..,..,..,..,..,..,..,..,..,....,..........

*****~~~~~.~~~~~~~~*~~*~~~~.~~~~*~~~~~.*~~~~

,....,..,..,..,....,..,..,..,............

figure 6

Retrieving a cell

To retrieve a cell you have to pick from the main menu:

> 1 Cell editing, EC

> 1 Merge cell, EC

The system will ask you the cell name and to which father frame the cell is connected to. The world

frame always is the default fatherframe. In the same way you can retrieve a device. To delete a cell.

device or tpoint press the desired option from menu followed by entering the entity. The delete

functions can also be executed by picking the object on the graphics screen with the mouse. To

create a t-point pick:

> 1 cell editing, EC

> 4 create tpoint, EC

18

The default tpoint will appear on the screen. A move of the tpoint can easily be performed.

If you want to save the contents of the current PLACE working cell and create a cell file in the user

directory, then pick:

> 12 Save Cell, EC

The cell will be saved and the PLACE main menu will appear again.

Robot motion and alignment

There are three types of robot motion:

- straight line motion

- joint interpolated

- slew

In case of straight line motion the working tpoint of the robot is constrained to follow a straight line

with respect to the robot base when aligning with the goto tpoint.

In the algorithm Euler's theorem is used. 'Euler's theorem states that given two coordinate systems

with the same origin but different axis directions, one of the coordinated systems can be rotated into

the other by rotating about a line through the origins. PLACE calculates this line and angle before

moving. The tool axis are rotated about this Euler-line. At the start of the move the rotation angle is

zero. At the end of the move the rotation change is equal to the Euler angle.

When Joint Interpolated is selected the robot will move all of Its Joints such that each of the joints

starts and stops at the same time. The set of joint values the robot moves toward are determined at

the beginning of the move. If there is more than one solution which will case the robot to align,

PLACE will always attempt to determine one that is within the limits of the joint.

Slew motion is similar to joint interpolation. The only difference is that each joint will move Indepen­

dently at a constant speed. Some of the joints may complete their motion before others.

If a device motion is desired pick from the PLACE main menu:

> 2 Device motion contro', EC

19

The next menu will appear:

-***********.***************************** .... McDonnell Douglas PLAC! Aelaase 6.0 .... Device Motion Control ..* 1 Active Device .... 2 Yorking !point .... 3 Coto Tpoint .... 4 Coto Joint Position$ .... 5 Coto Home .... 6 Coordinated Goto .... 7 Coto Position .... 8 Set nevice Mo~ion Mode .... 9 Set nevice Speed .... 10 Tracking On/Off .... 11 Connect Frames .... 12 Disconnect Frames .... 13 Set nevice Kotion Parameters .... l~ Goto Circle .... ..*********.**••• *•••••~.*.*.*********••

figure 7

To perform the 'goto tpoint'-command, the device must have a working tpoint defined. The working

tpoint is the tpoint that aligns with the goto tpoint at the end of a successful 'goto tpoint command'.

Usually the working tpoint of a robot is either connected to the faceplate of the robot or is connec­

ted to a frame that is descendent of the faceplate in the connection tree. In the simulation the

working tpoint Is connected to fatherframe world. As the CLS-file already is connected to the

faceplate and the goto- and working tpoint never can be connected to the same fatherframe when

alignment is desired, the working tpoint of device 2 is connected to world.

Goto tpoint may now be used to direct the active device to align its working tpoint with one or more

tpoints in the cell. The path the robot performs when aligning a tpoint depends on:

- the device type

- on the motion mode currently in effect for the device (I.e. straight line, joint

Interpolated, slew)

- on the position of the tpoint

- the relative position of the goto and working tpoint.

20

Compound devices

A Compound Device describes a device composed of two or more simple kinematic devices. A

Coordinated Motion Device is a compound device which allows the simulation and programming of

more than one device using simultaneous motion. The coordinated motion is used to cause all of the

sub-devices of the coordinated motion device to move. The motion of each sub-device will be

prorated such that each sub-device will start and stop at the same time.

A Dependent Motion Device is a compound device whose Joint solution is always dependent on the

position of some other devices in a cell. This allows the capability of the simulation of closed loop

mechanisms and the driving of linkages of robots.

In this project a coordinated motion device is used. To perform a coordinated goto first a compound

device has to be defined. So pick:

> 2 Device Motion Control, EC

To define a compound device press:

> 13 Set device motion parameters, EC

> 11 Define compound device, EC

> 1 Define coordinated motion device, EC

> Enter compound device name, EC

The following menu will appear:

"""'**""""'*'*"*'*"**"**""'**"'*'**""""""""*"; ;

; McDonnell Douglas PLACE ~ele&Se 6.0 ;; Select Editing Mode for Coordinated Motion Device COMPDEV ;; 1 Add Sub· Devices to Compound Device ;; 2 l.elDove Sub-Devices froD eo.pound Device ;; 3 Examine Sub-Devices of CoIrpound Device ;; 4 Update Compound Device Definition ;; ;

'*****'***'*'*""""*""""""*"","""*"""""*"*"'*'

figure 8

Add the sub-devices to the compound device:

> 1 Add sub-devices to compound device, EC

The system will ask to enter the device names:

> name device 1, EC

> name device 2, EC

21

Now the compound device has to be updated:

> Term

> 1 Define coordinated motion device, EC

> 4 Update compound device, EC

Pick two times Term to return to the main menu.

Before using the coordinate motion command, set the working tpoints for both active devices. Pick:

> 2 Device motion control, EC

>1 Active device, EC

> Enter device name or pick with the mouse on the screen

> 2 Working tpoint, EC

> Enter working tpoint or pick with the mouse on the screen

For the second device the same procedure has to be followed.

To perform the coordinated goto pick:

> 6 Coordinated goto, EC

This option allows you to specify the desired motion device for each component of the compound

device. For each sub-device within the compound device you must select in which way the motion

will be performed (goto joints, goto home, etc.). After having defined the motion specifications for

each sub-device, the coordinated motion can be performed.

Sequences

A PLACE sequence is a stored series of PLACE functions that may be replayed to simulate a robotic

workcell process. Generally a sequence includes all information about the motion within a specific

cell. Sequence editing allows you to create a new device or to modify an existing device. To create a

sequence choose from the PLACE main menu:

> 6 sequence editing and control, EC

> 3 edit sequence, EC

As the sequence editing mode is active now, all sequence statements may be defined by using

PLACE options.

22

UG II CLSF to PLACE conversion

The CAM-module of UG II is capable of generating CLS-files. Within PLACE there is an option

available to convert a CLS-file from UG II to PLACE. Pick:

> 10 File Management, EC

> 3 Unigraphics 11 CLSF to PLACE conversion, EC

The system will ask for a UG II username and password as well as the .CLS file. A cell containing a

frame with all tpoints that represent the tooling of the product and a sequence which directs a robot

to follow the path will be generated. To set the CLS-file to the center of the faceplate its fatherframe

has to be changed. So pick:

> 1 Cell editing, EC

> 10 Connect tpoint, EC

The system will ask for the tpoint to connect to and the new fatherframe. Enter tpolnt 1 of the CLS­

file as the tpoint to connect to and the faceplate frame as the new fatherframe. Finish with EC. Now

the move of tpoints can be performed. Pick:

> 3 Move framesjtpoints, EC

> 4 Align tpoints, EC

Enter tpoint 1 of the generated CLS-file cell as the tpoint to align and the faceplate orientation tpoint

as the tpoint to align with. The simulation can now be performed.

Collision detection

To operate the collision detection, It is determined if two parts occupy the same space at the same

time.

Collision detection is initiated by picking from the PLACE main menu:

> 9 Collision detection

The procedure is as follows. First the solids for the frame parts which might collide must be defined.

> 3 Define solids, EC

Then the pairs of frames to be involved in the collision detection have to be selected.

> 4 AllowjDisallow collisions. EC

> 5 Select pair of frames not allowed to collide. EC

Pick the desired frames with the mouse on the screen.

The collision detection can now be turned on:

> 1 Collision detection Onj Off

23

The method for the collision detection must be chosen now. This can be whether a velocity detection

or a fixed interval check. Pick:

> 2 Select collision detection method, EC

> 1 Fixed interval, EC

The simulation may now be initiated by performing a device goto or executing a sequence.

24

APPENDIX 4 BUILD

In this BUILD summary a system overview and a short manual of the main options used in this

project are regarded. For the complete extend of the BUILD possibilities, see the BUILD manual.

System overview

The BUILD-Module enables the user to describe new robots or other kinematic motion devices.

Using BUILD the geometric model of a robot is automatically combined with Its unique kinematic

description for animation in PLACE. With a minimal knowledge of robot kinematics you are able to

add new devices to the PLACE library.

BUILD is capable of automatically generating the kinematic equations from devices which have up to

6 degrees of freedom. BUILD supports devices up to 12 degrees of freedom, but it does not

automatically generate the kinematic control equations. The BUILD user may optionally write a

programme which defines the kinematic equations for any device with up to 12 axes. To obtain

complete functionality, the device must be separable into arm and wrist components.

The BUILD menu structure adhere to the same rules as PLACE. The user must fill in menu items in

order to fully describe the characteristics of the device. Once all necessary information has been

entered. BUILD may be directed to create the files which contain the description of the device. This

robot or device can now be used in PLACE.

An outline of the steps required for creating robots or devices is as follows:

- The user creates a model of robot or device on UG II.

- The user collects the input data for the BUILD module.

- The user transfers the CAD data to the PLACE data base.

- The user inputs the parameters which define the device in BUILD.

- The BUILD software generates the kinematic data which is used to simulate

the motion of the robot or device in PLACE.

BUILD directs the user to define the kinematic model of a device. which is used by PLACE to drive

the simulation. Additional controller information is supplied which is used by COMMAND to provide

for off-line programming. BUILD places restrictions on the types of linkages which may be automati­

cally modeled with complete functionality, what is meant to be all inverse solutions. If a device does

not meet these restrictions it may still be modeled, but with a much more limited functionality. The

user may retain complete functionality by writing a programme which supplies the kinematic

algorithms needed for simulation.

25

BUILD file types:

There are three file types which are created by BUILD. These are the files used by BUILD to describe

a robot or device.

- BUILD-file (.BLD) : The BUILD-file contains the basic device description.

It keeps a record of all information which has been entered into BUILD. This file may be

used to edit the parameters of an existing device or simply by means of displaying device

parameters. The BUILD file is not used by PLACE, COMMAND or ADJUST

- DEVICE-file (.DEY) : The Device-file contains the connection tree which

describes the device along with the link names and the associated part

names. The Device file points at the Device Control Information-file.

- DEVICE CONTROL INFORMATION-file (.DCI): The Device Control

information-file defines device characteristics for the device. Such

Information as the kinematic attributes of the device. the allowable motion

modes, the maximum joint speeds and accelerations, and more is stored In

this file. PLACE, COMMAND and ADJUST obtain their kinematics from this device.

The next files are referred to by BUILD but not actually used.

- PART-file (.PAR): The part file contains the graphical display data for each

link of the device. This file is created by the UG II to PLACE utilities.

- COORDINATED SYSTEM INFORMATION (.CRD): Coordinated System

Information files define the attributes of particular ·coordinate

systems· that are used to represent robot arm positions. tool tip position

constraints, etc. Crd-files are also used for Dependent Joints Mapping and

Similar Device Kinematics Mapping. These files can be defined by using the text

editor.

26

Accessing BUILD

Build may be accessed in two ways. The First way is to run the module directly from the operating

system. The second method is to run BUILD from the PLACE file management Menu. In this case

BUILD is running separately from PLACE, so any action which occurs in BUILD will have no effect on

the PLACE session.

To enter BUILD select from the PLACE main menu:

> 10 file management, EC

> 8 BUILD, EC

Besides having easier access to BUILD, the ability to access BUILD from PLACE also allows the

user to examine device characteristics without haVing to exit PLACE. It is not needed if not desired

to generate new device description files when examining this data.

Part file creation for BUILD:

The creation of a device in BUILD is accomplished by specifying a series of transformations which

describe the relationships between the links of the device. The geometry for each part must be

created on a CAD-system as a separate part. Each part should be modeled such that the axis of

motion is located in the absolute coordinate system. This allows the motion of each link to be

defined as either a translation along or a rotation about its absolute coordinate system.

Take care that the axis pointing out of the end of the device has to be the X-axis as this Is a device

requirement. The orientation tpoint should be positioned at the faceplate as the CLS-file will be

connected to this tpoint.

Once the location of each link coordinate system is known, the transformations between these

coordinate systems may be defined. The user must determine the relationship between each

consecutive link. This relationship must be described as a series of constant and/or variable

transformations. A constant transformation describes either a translational or rotational offset that

never changes, regardless of the positioning of the joints of the device. A variable transformation

defines the motion of a joint and may be either translations or rotations. All transformations are

defined using the right hand rule. This rule defines the direction of a positive rotation.

27

After having entered BUILD, the system will ask a device name. Then the user has to choose

whether to edit an existing device or to define a new device. When defining a new device. BUILD will

ask for the type of device and the distance units. After pressing EC, the BUILD main menu will

appear (fig. 9) .

•••••••• *•••• *.** ••• **** •• *************************.************ McDonnell Douglas BUILD Release 6.1* Robo~ "ABC" Defini~ion Main Menu Uni~s - (IN)* l>*Kinema~ic Transform&~ions

* 2 *Arm Configurations* 3 Mo~ion Modes* 4 Tool Tpoin~ Informa~ion

* 5 Off· line Programming Coord1na~e Sy.~ems

* 6 Device Po.i~ion with Respec~ ~o Father Frame* 7 *Link/Par~ Names* 8 Source of Inver•• Kinema~ic.

* 9 Se~ Dis~ance Uni~5

* 10 Exi ~ BUILD*

**************

******.*************************************************'*'***

figure 9

Each of these items should be selected in order to fully describe the device. To input all kinematic

transformations pick:

> 1 Kinematic transformations, EC

After having entered the type of information (constant, variable joint or dependent joint) one can

specify the connected data.

In case of more alignment solutions, the arm configuration must be chosen which may be obtainable

to the device. Pick:

> 2 Arm configurations, EC

The motion mode (straight line, joint interpolated or slew) can be set by picking:

> 3 Motion modes

Modes 4 and 5 are not actually used in this project but may in some cases be necessary to be

entered.

When designing a cell it might be desired to position a device not in the origin of the fatherframe.

Option 6 has to be entered to set a device with respect to its fatherframe.

Using option 7 the part-files can be linked to the .BLD file.

28

In case the robot does not yield a proper alignment option 8 has to be used. Pick:

> 8 Source of inverse kinematics, EC

> 4 Kinematics from similar device, EC

The system will ask the similar device name and the joint mapping .CRD file. The similar device used

during this simulation was a six axis device with two dummy axis. The .CRD file removes these

dummy axis.

Option 9 may be selected to set the distance units.

When all data has been entered pick:

> 10 Exit BUILD, EC

BUILD will automatically generate the .BLD, the .DCI and the .DEV files. All entered information will

be used in the display of the device in PLACE. The link names will be used as the frame names in

PLACE.

Sources of inverse kinematics

Inverse kinematics is the process used to convert a position and orientation (Le. t-points) into the

joint values of a device. Although PLACE uses built-in algorithms that will support most robots, it is

possible to obtain the analysis from other sources.

- Standard kinematics: The normal mode for device modelling is to use BUILD to automatically

generate the inverse kinematic parameters to be used by the PLACE kinematic analyzer.

- No inverse kinematics: If BUILD for some reason could not generate the inverse kinematic

parameters for a particular device, the PLACE kinematic analyzer will not be able to perform the in­

verse kinematics. Such a device can only be simulated in PLACE in a limited manner. A device

without inverse kinematics can not be directed to move to a tpolnt. The only motion specifiers

supported are : goto joint position and goto home.

- External inverse kinematics: A device may be defined which obtains its inverse

kinematics from an external programme. When this option is used, the automatically generated

kinematic algorithms will not be used. This option is useful when the PLACE kinematic analyzer does

not give the desired results. An external kinematics programme may be the only way to simulate for

example a seven degrees of freedom robot, which BUILD doesn't support. The external programme

should be able to compute joint angles when given a position and orientation.with which to align

with.

- Similar Device Kinematics: Similar Device Kinematics allow the inverse kinematics of a device to

come from a definition of a different device. During the simulation, whenever PLACE needs an

29

inverse kinematic solution, it will use the kinematic solution defined for a similar device. The results of

the inverse kinematics are then mapped to a new set of joint values via a coordinated system file. All

joint limits will be checked against this new set of values. The automatic kinematic algorithms derived

by BUILD occasionally do not yield the desired alignment results for devices with less than six

degrees of freedom. In this, PLACE offers a possibility to add joints to a similar device which will

cause it to work properly when 6 degrees of freedom are being defined. PLACE computes the

desired joints of the similar device and a coordinated mapping file will map this joints on device 2

and remove the unwanted joints.

30

Appendix 5 Instructions for 8 succeeding student

In this work the cell freesbank has been created. The cell is composed of two devices, freestafS and

freesb. To retrieve the cell the next instructions have to be followed.

> Enter PLACE

> 10 File management, EC

> 7 Change search directory, EC

> Enter /users/vern/freesba5, Enter

> Return to ~he PLACE main menu

> 1 Cell editing, EC

> 1 Merge cell, EC

> Enter freesbank, EC

The cell Freesbank will be displayed.

In case only a device is desired to be displayed follow the same procedure as for retrieving a cell but

Instead of 1 Merge cell press 2 Merge device followed by entering the device name.

To start the simulation the sequence 'freesbank' has to be retrieved. This can be done by picking

from the main menu:

> 6 Sequence editing and control

> 1 Run sequence

> Pick with the mouse the option Int/Res

The simulation will now be performed.

The created orientation tpolnt has the next joint values:

Device freestafS: Joint1: -230

Joint2: 272

Joint3: 0

Joint4: 0

Device freesb: Joint1: 237

Joint2: 0

The parts of the devices in UG II are stored named freestafS and freesb. Each frame is drafted on a

different layer.

31

Appendix 6 The Build files

32

;**~*** BUILD Release 7.0 ***~*~

DEVICE NAME = FREESBDEVICE TYPE = ROBOTUNITS = MILLIMETERS

*******

ConstantRotation aboutZ axisAmount = -90.0000 (DEG)

*******

ConstantTranslation alongX axisAmount = -1480.0000 (MH)

ConstantTranslation alongY axisAmount = 525.0000 (HH)

*******

ConstantTranslation alongZ axisAmount = 1250.0000 (HH)

*******

VariableTranslation along-z axisJoint Name = FREESBlJoint Constraints --High Value = 1000.0000 (HH) Low Value = -1000.0000 (HM)Home Position = 0.0000 (HH)Joint Speed = 100.0000 (HH/SEC)Joint Acceleration = 10.0000 (MH/SEC/SEC)END OF LINK

*******

Constant,Rotation aboutX axisAmount = 90.0000 (DEG)

*******

VariableRotation aboutZ axisJoint Name = FREESB2

Joint Constraints --High Value = 360.0000 (DEG) Low Value = -360.0000 (DEG)Home Position = 0.0000 (DEG)Joint Speed = 100.0000 (DEG/SEC)Joint Acceleration = 10.0000 (~EG/SEC/SEC)

END OF LINKEND OF DEVICE

INVERSE KINEMATICS DATA -­SOURCE -- STANDARD

CONFIGURATIONS==

SHORT REACH OF JT 1 = SHORT REACH OF JT 1LONG REACH OF JT 1 = LONG REACH OF JT 1

==

Initial Configuration = 1

MOTION TYPESNUMBER OF TYPES = 1JOINTHOME MOTION TYPE = JOINT

TOOL COORDINATE SYSTEM =MAX TOOL SPEED = 0.0000 (MM/SEC)MAX TOOL ACCEL = 0.0000 (MM/SEC/SEC)

COORDINATE SYSTEM REPRESENTATIONSNUMBER OF COORDINATE SYSTEMS = 0

World to Robot Base Transformation -­Translations

0.0000 0.0000 0.0000 (MM)Rotations --

0.0000 45.0000 0.0000 (DEG)

Link HamesNumber of Links = 3

1. FREESBO2. FREESBI3. FREESB2

Part Names --Number of Parts = 3

1. FREESBO2. FREESBl3.

;****** BUILD Release 7.0 ******

DEVICE NAME = FREESTAF6DEVICE TYPE = ROBOTUNITS = MILLIMETERS

*******

ConstantTranslation alongZ axisAmount = 500.0000 (HH)

*******

ConstantTranslation alongY axisAmount = 500.0000 (MM)

*******

ConstantTranslation alongX axisAmount = -600.0000 (MH)

VariableTranslation along-Y axisJoint Name = FREESTOJoint Constraints --High Value = 1000.0000 (HM) Low Value = -1000.0000 (HM)Home Position = 0.0000 (HM)Joint Speed = 100.0000 (HM/SEC)Joint Acceleration = 10.0000 (MM/SEC/SEC)END OF LINK

*******

ConstantTranslation alongZ axisAmount = 250.0000 (HM)

*******

ConstantTranslation alongX axisAmount = 500.0000 (HM)

*******

VariableTranslation alongX axisJoint Name = FREEST2

Joint Constraints --High Value = 1000.0000 (MM) Low Value = -1000.0000 (MM)Home Position = 0.0000 (MM)Joint Speed = 100.0000 (MM/SEC)Joint Acceleration = 10.0000 (MM/SEC/SEC)END OF LINK

*******

ConstantTranslation alongX axisAmount = 50.0000 (MM)

*******

ConstantTranslation alongY axisAmount II: 400.0000 (MM)

*******

ConstantTranslation alongZ axisAmount = 250.0000 (HM)

*******

VariableRotation aboutX axisJoint Name = FREEST3Joint Constraints --High Value = 150.0000 (DEG) Low Value = -150.0000 (DEG)Home Position = 0.0000 (DEG)Joint Speed. 100.0000 (DEG/SEC)Joint Acceleration = 10.0000 (DEG/SEC/SEC)END OF LINK

ConstantRotation aboutZ axisAmount = 90.0000 (DEG)

*******

ConstantTranslation alongY axisAmount = -160.0000 (MM)

*******

ConstantTranslation alongX axis

Amount = 180.0000 (MM)

VariableRotation about-x axisJoint Name = FREEST4Joint Constraints --High Value = 150.0000 (DEG) Low Value = -150.0000 (DEG)Home Position = 0.0000 (DEG)Joint Speed = 100.0000 (DEG/SEC)Joint Acceleration = 10.0000 (DEG/SEC/SEC)END OF LINK

*******

ConstantTranslation alongX axisAmount = 234.0000 (MM)

*******

ConstantTranslation alongY axisAmount s 26.3120 (MM)

*******

ConstantTranslation alongZ axisAmount = -93.2250 (MM )

*******

ConstantRotation aboutZ axisAmount s -90.0000 (DEG)END OF LINKEND OF DEVICE

*******

INVERSE KINEMATICS DATA -­SOURCE -- STANDARD

*******

CONFIGURATIONS=====

Initial Configuration = 2

******:It

MOTION TYPESNUMBER OF TYPES =STRAIGHTJOINTHOME MOTION TYPE = JOINT

TOOL COORDINATE SYSTEM =MAX TOOL SPEED = 0.0000 (MM/SEC)MAX TOOL ACCEL = 0.0000 (MM/SEC/SEC)

*******

COORDINATE SYSTEM REPRESENTATIONSHUMBER OF COORDINATE SYSTEMS = 0

*******

World to Robot Base Transformation -­Translations

110.0000 100.0000 -91.0000 (MM)Rotations --

0.0000 45.0000 0.0000 (DEG)

*******

Link HamesNumber of Links = 6

1. FREESTAFO2. FREESTAFl3. FREESTAF24. FREESTAF3S. FREESTAF46. FREESTAFS

Part NamesHumber of Parts = 6l. FREESTO... FREESTl~ .3. FREEST24. FREEST3S. FREEST46. BOLBOB