Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This thesis describes the process of developing a user interface for a seven
degree of freedom (DOF), minimally invasive surgical robot. For the first two main
stages of the overall project, completed by previous students, a primary slave
manipulator (PSM) and a secondary slave manipulator (SSM) were developed.
The stage in this thesis concentrates on creating a joystick that can control the
combined movement of the PSM and SSM.
Background information on the field of robotic surgery, with specific reference to
current systems’ user interfaces, is given and the technical aspects of the PSM
and SSM are determined. This is followed by the motivation and main objectives
of the thesis. Objectives were divided into the main categories of mechanical
design, electronic design, control system design and testing.
The mechanical design of the joystick progresses through a concept
development stage, before a final seven DOF articulated arm design is presented
and evaluated based on engineering specifications. Aluminium is used as the
construction material; electromagnetic brakes are specified for each joint, leading
to the final assembly, which is a constructed joystick fulfilling all requirements.
The electronic design implements magnetic rotary encoders for the joystick’s
position and orientation tracking as well as designs of the necessary power and
control circuitry to enable correct joystick functioning. The interfacing of the PSM
and SSM had to enable successful communication capabilities between the
master and the slave. Several necessary adjustments were therefore made to the
slave system, after which the joystick and robot were electronically interfaced to
provide a direct serial communication line.
For control system design, the joystick and robot were modelled according to the
Denavit-Hartenberg principle, which allows direct relation between the position
and orientation of the respective end effectors on the joystick and robot sides.
Forward kinematic equations were then applied to the joystick; the desired
position and orientation of the robot end effector were determined, and inverse
kinematic equations were applied to these data to establish the robot’s joint
variables. This stage ended with the development of two operational modes: one
where only the SSM motors are controlled in order for the slave to follow the
master’s movements, and the other where the PSM’s motors are controlled
separately. The simultaneous control of all robot motors could not be
demonstrated due to fundamental mechanical flaws in the PSM and SSM
designs. Finally, testing was undertaken to demonstrate movement control of the robot by
the joystick. The intuitiveness of the product was also tested successfully. The
study ends with the presentation of the conclusions, the main conclusions being
the successful development and testing of a joystick that controls the movement
of a surgical robot, as well as the achievement of all main thesis objectives. / AFRIKAANSE OPSOMMING: Hierdie tesis beskryf die proses vir die ontwikkeling van ’n gebruikerskoppelvlak
vir ’n sewevryheidsgraad-, minimaal indringende chirurgiese robot. In die eerste
twee hoofstadia van die algehele projek, voltooi deur ander studente, is ’n
primêre slaafmanipuleerder (PSM) en ’n sekondêre slaafmanipuleerder (SSM)
ontwikkel. Die stadium in hierdie tesis konsentreer op die skep van ’n stuurstok
waarmee die gekombineerde beweging van die PSM en SSM beheer kan word.
Agtergrondinligting oor die gebied van robotiese chirurgie word verskaf, met
spesifieke verwysing na die gebruikerskoppelvlakke van huidige stelsels, en die
spesifikasies van die PSM en SSM word vasgestel. Daarna volg die beweegrede
sowel as die belangrikste oogmerke van die projek. Die oogmerke is in die
hoofafdelings van meganiese ontwerp, elektroniese ontwerp,
beheerstelselontwerp en toetsing verdeel.
Die meganiese ontwerp van die stuurstok behels ’n konsepontwikkelingstadium,
wat uitloop op ’n finale sewevryheidsgraad-ontwerp, wat dan op grond van
ingenieurspesifikasies aangebied en beoordeel word. Aluminium word as
boumateriaal gebruik; elektromagnetiese remme word vir elke koppeling
gespesifiseer, en die finale samestel is ’n gekonstrueerde stuurstok wat aan alle
vereistes voldoen.
Die elektroniese ontwerp behels die gebruik van magnetiese draaikodeerders om
die stuurstok se posisie en oriëntasie te bepaal, sowel as meganismes met die
nodige krag- en beheerstroombaanwerk om die stuurstok reg te laat funksioneer.
’n Koppelvlak tussen die PSM en die SSM moes suksesvolle kommunikasie
tussen die meester en die slaaf bewerkstellig. Verskeie nodige aanpassings is
dus aan die slaafstelsel aangebring, waarna die stuurstok en robot elektronies
gekoppel is om ’n direkte reekskommunikasielyn te skep.
Vir beheerstelselontwerp is die stuurstok en robot volgens die Denavit-
Hartenberg-beginsel gemodelleer, wat ’n direkte verhouding tussen die posisie
en oriëntasie van die onderskeie eindpunt-effektors aan die stuurstok- en
robotkant daarstel. Voorwaartse kinematiese vergelykings is daarna op die
stuurstok toegepas; die gewenste posisie en oriëntasie van die robotiese
eindpunt-effektor is bepaal, waarna terugwaartse kinematiese vergelykings op
hierdie data toegepas is om die robot se koppelingveranderlikes te bepaal.
Hierdie afdeling word afgesluit met die ontwikkeling van twee bedryfsmodusse:
een waar slegs die SSM-motore beheer word sodat die slaaf die meester se
bewegings kan navolg, en die ander waar die PSM se motore afsonderlik beheer
word. Die gelyktydige beheer van al die robotmotore kon nie getoon word nie
weens fundamentele meganiese tekortkominge in die PSM- en SSM-ontwerp. Laastens is ’n toets uitgevoer om die bewegingsbeheer van die robot deur die
stuurstok te toon. Die intuïtiwiteit van die produk is ook suksesvol getoets. Die
studie sluit af met die projekgevolgtrekkings, waarvan die belangrikste die
suksesvolle ontwikkeling en toetsing van ’n stuurstok is wat daarin slaag om die
beweging van ’n chirurgiese robot te beheer, sowel as die verwesenliking van
alle hoofprojekoogmerke.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/71833 |
| Date | 12 1900 |
| Creators | Heunis, Jacobus Stephanus |
| Contributors | Scheffer, C., Schreve, K., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 123 p. : ill. |
| Rights | Stellenbosch University |
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