No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 192-196).

Thesis (Ph. D.)--Ohio State University, 1986. / Includes vita. Includes bibliographical references (leaves 132-136). Available online via OhioLINK's ETD Center.

Thesis (Ph. D.)--Carnegie-Mellon University, 1984. / Bibliography: p. 260-266.

There are several advantages to replacing CNC machinery with robotic machine tools and as such robotic machining is emerging into the manufacturing and metal cutting industry. There remain several disadvantages to using robots over CNC stations primarily due to flexibility in robotic manipulators, which severely reduces accuracy when operating under high machining forces. This flexibility is dependent on configuration and thus the configuration can be optimised through posture selection to minimise deflection. In previous work little has been done to account for operating frequency and the additional complications that can arise from frequency dependent responses of robotic machine tools. A Fanuc S-360 manipulator was used to experimentally investigate the benefits of including frequency compensation in posture selection. The robot dynamics first had to be identified and experimental modal analysis was selected due the inherent dependency on frequency characteristics. Specifically, a circle fit operation identified modal parameters and a least squares optimisation generated dynamic parameters for a spatial model. A rigid-link flexible-joint model was selected and a pseudo-joint was used to create an additional DOF to accommodate link flexibility. Posture optimisation was performed using a gradient-descent algorithm that used several starting points to identify a global minimum. The results showed that a subset of modal data that excluded the mode shape vectors could be used to create a model to predict the manipulator vibration response. It was also found that the receptance variation of the manipulator with configuration was insufficient to verify the optimisation throughout the entire selected workspace; however the model was shown to be useful in regions containing multiple peaks where the modelled dynamics were dominant over the highly volatile measured data. Simulations were performed on a redundant planar manipulator to overcome the lack of receptance variation found in the Fanuc manipulator. These simulations showed that there were two mechanisms driving the optimisation; overall amplitude reduction and frequency specific amplitude reduction. Using a stiffness posture measure for comparison, the results of the frequency specific reduction could be separated and were found to be particularly beneficial when operating close to resonant frequencies.

There are several advantages to replacing CNC machinery with robotic machine tools and as such robotic machining is emerging into the manufacturing and metal cutting industry. There remain several disadvantages to using robots over CNC stations primarily due to flexibility in robotic manipulators, which severely reduces accuracy when operating under high machining forces. This flexibility is dependent on configuration and thus the configuration can be optimised through posture selection to minimise deflection. In previous work little has been done to account for operating frequency and the additional complications that can arise from frequency dependent responses of robotic machine tools. A Fanuc S-360 manipulator was used to experimentally investigate the benefits of including frequency compensation in posture selection. The robot dynamics first had to be identified and experimental modal analysis was selected due the inherent dependency on frequency characteristics. Specifically, a circle fit operation identified modal parameters and a least squares optimisation generated dynamic parameters for a spatial model. A rigid-link flexible-joint model was selected and a pseudo-joint was used to create an additional DOF to accommodate link flexibility. Posture optimisation was performed using a gradient-descent algorithm that used several starting points to identify a global minimum. The results showed that a subset of modal data that excluded the mode shape vectors could be used to create a model to predict the manipulator vibration response. It was also found that the receptance variation of the manipulator with configuration was insufficient to verify the optimisation throughout the entire selected workspace; however the model was shown to be useful in regions containing multiple peaks where the modelled dynamics were dominant over the highly volatile measured data. Simulations were performed on a redundant planar manipulator to overcome the lack of receptance variation found in the Fanuc manipulator. These simulations showed that there were two mechanisms driving the optimisation; overall amplitude reduction and frequency specific amplitude reduction. Using a stiffness posture measure for comparison, the results of the frequency specific reduction could be separated and were found to be particularly beneficial when operating close to resonant frequencies.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 29, 2008) Includes bibliographical references.

Serial articulated industrial manipulators are increasingly used in machining applications due to their flexibility in application and their cost-effectiveness compared to conventional machinery. However, the use of industrial manipulators in machining processes that subject the robot to high loads such as in drilling is limited. The relatively low mechanical stiffness leads to position offsets from the anticipated position. Efforts have been made in the past to create manipulator calibration methods to compensate for their low stiffness and to increase their pose accuracy. The Department of Production Engineering at KTH Royal Institute of Technology defined a static and quasi-static compliance calibration procedure for industrial manipulators. Contrary to the hypothesis, the two methods produce different results in terms of the measured magnitude of Cartesian deflections. This study compares static and quasi-static compliance measurement procedures on an ABB IRB 6700-300/2.70 and aims at finding causes for the difference in the measured deflection of the manipulator between the two methods. Therefore, a literature review is performed and based on the review a novel quasi-static measurement procedure is presented. Deflections during the application of static and quasi-static loads with a frequency of less than 0.5 Hz on the manipulator are measured and compared. Differences in deflection are seen and potential causes are analyzed in several experiments. Namely, by changing parameters the resulting effects on the manipulator due to kinematic errors and dynamic effects are investigated. The results stress that unlike the expectation based on the theory of mechanics the system shows a dynamic behavior if a periodic loading with a frequency of less than 0.5Hz is applied during the quasi-static experiments. The difference in deflection is thus explained through load dissipation by damping and inertial forces during the quasi-static measurements of the novel method. This does not apply to the quasi-static measurement procedure defined by the Production Engineering department. Moreover, differences in deflection were identified due to friction and backlash acting in the transmissions system of the motors when static loads are applied in certain regions of the task space. Future work in the analysis of differences in compliance measurement procedures is encouraged to find causes for the quasi-static measurement results of the department. / Serieartikulerade industriella manipulatorer används allt mer i bearbetande operationer tack vare dess flexibilitet i användande och dess kostnadseffektivitet jämfört med konventionella maskiner. Dock är användandet av industriella manipulatorer i bearbetningsprocesser som utsätter roboten för höga laster så som borrande begränsat. Den relativt höga mekaniska stelheten leder till positionsförskjutningar från den förväntade positionen. Ansträngningar har tidigare gjorts för att skapa kalibreringsmetoder för manipulatorer som ska kompensera för dess låga stelhet och öka dess position och orienterings-exakthet. Institutionen för industriell produktion vid Kungliga Tekniska Högskolan har definerat en statisk och kvasistatisk efterlevnads-kalibrerings-procedur för industriella manipulatorer. I motsats till hypotesen producerade de två metoderna olika resultat i avseende till den uppmätta magnituden för Kartesiska böjningar. Denna studie jämför statiska och kvasistatiska efterlevnads-mätnings-procedurer hos en ABB IRB 6700-300/2.70 och siktar på att hitta orsaker för skillnaden i den uppmätta böjningen av manipulatorn mellan de två metoderna. Därmed genomförs en litteraturstudie och baserat på en översikt presenteras en ny kvasistatisk mätningsprocedur. Böjningar under påverkan av statiska och kvasistatiska laster på under 0.5 Hz på manipulatorn uppmäts och jämförs. Skillnader i böjningar kan ses och potentiella orsaker analyseras i flera experiment. Genom byte av parametrar kan effekter på den industriella manipulatorn som orsakas av kinematiska fel och dynamiska effekter undersökas. Resultatet understryker att olikt förväntningarna som baserats på teorier från mekaniken uppvisar systemet ett dymaniskt beteende om en periodisk last på mindre än 0.5 Hz appliceras under de kvasistatiska experimenten. Skillnaden i böjningen förklaras därmed genom ett lastminskande som beror på dämpande och tröga krafter under de kvasistatiska mätningarna av den nya metoden. Detta gäller inte den kvasistatiska mätningsproceduren som definerats av Institutionen för industriell produktion. Utöver detta identifieras skillnader i böjningar med avseende på friktion och glapp i överföringssystemet i motorerna när statiska laster appliceras på specifika regioner i arbetsområdet. Framtida arbete i analys av skillnader i efterlevnadsmätnings-procedurerna uppmuntras för att hitta orsaker till institutionens kvasistatiska mätningsresultat.