Chris Forden, Yanuel Trinidad, Ryan von Chance-Stutler, A. Bellocchio, James Bluman, M. Lanzerotti
This paper proposes a new approach to stabilize the spin of a suspended litter during air ambulance rescue hoist operations. Complex forces generated by the helicopter’s downwash may cause a patient suspended in a rescue litter to spin violently. In severe cases, the spin destabilizes the suspended load, risks injury to the patient, and jeopardizes the safety of the aircrew. The presented design employs an anti-torque device to arrest the spin that is safer and faster than a tagline and is without the tactical constraints of the tagline. The device follows tailored control laws to accelerate a flywheel attached to the litter, thereby generating sufficient angular momentum to counteract the spin and stabilize the suspended litter. An inertial measurement unit (IMU) measures the position, angular velocity, and angular acceleration of the litter and delivers this information to a microcontroller. The research and prototype design were developed under the support of the U.S. Army 160th Special Operations Aviation Regiment (SOAR).
{"title":"Spin Stabilization of an Air Ambulance Litter","authors":"Chris Forden, Yanuel Trinidad, Ryan von Chance-Stutler, A. Bellocchio, James Bluman, M. Lanzerotti","doi":"10.1115/IMECE2020-23386","DOIUrl":"https://doi.org/10.1115/IMECE2020-23386","url":null,"abstract":"\u0000 This paper proposes a new approach to stabilize the spin of a suspended litter during air ambulance rescue hoist operations. Complex forces generated by the helicopter’s downwash may cause a patient suspended in a rescue litter to spin violently. In severe cases, the spin destabilizes the suspended load, risks injury to the patient, and jeopardizes the safety of the aircrew.\u0000 The presented design employs an anti-torque device to arrest the spin that is safer and faster than a tagline and is without the tactical constraints of the tagline. The device follows tailored control laws to accelerate a flywheel attached to the litter, thereby generating sufficient angular momentum to counteract the spin and stabilize the suspended litter. An inertial measurement unit (IMU) measures the position, angular velocity, and angular acceleration of the litter and delivers this information to a microcontroller.\u0000 The research and prototype design were developed under the support of the U.S. Army 160th Special Operations Aviation Regiment (SOAR).","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73475017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lars Schiller, Duraikannan Maruthavanan, A. Seibel, J. Schlattmann
In order to control high-level goals such as walking speed and direction or position of legged robots, a locomotion controller is required. This complicated task can be solved in many different ways. The approach presented here selects the optimal gait pattern from a discrete, predefined set of possibilities to get closer to a given target position. The method is based on an off-line component: elementary gait patterns are generated by trajectory optimization using a simulation model, and an on-line component: for given robot and target positions the optimal next elementary gait pattern is chosen based on a minimization problem, and the joint space references are derived from it. To ensure feasible subsequent poses, the elementary patterns always begin and end with one and the same pose, so that they can be placed on top of each other like Lego bricks. A great advantage of this method is a straightforward transition between different motion modes, such as switching from trotting to crawling. It is discussed how many different elementary patterns are needed to ensure a stable locomotion control. Finally, in simulation and experiment, it is shown that the robot can master any obstacle course using the proposed locomotion controller.
{"title":"Kit Based Motion Generator for a Soft Walking Robot","authors":"Lars Schiller, Duraikannan Maruthavanan, A. Seibel, J. Schlattmann","doi":"10.1115/IMECE2020-23151","DOIUrl":"https://doi.org/10.1115/IMECE2020-23151","url":null,"abstract":"\u0000 In order to control high-level goals such as walking speed and direction or position of legged robots, a locomotion controller is required. This complicated task can be solved in many different ways. The approach presented here selects the optimal gait pattern from a discrete, predefined set of possibilities to get closer to a given target position. The method is based on an off-line component: elementary gait patterns are generated by trajectory optimization using a simulation model, and an on-line component: for given robot and target positions the optimal next elementary gait pattern is chosen based on a minimization problem, and the joint space references are derived from it. To ensure feasible subsequent poses, the elementary patterns always begin and end with one and the same pose, so that they can be placed on top of each other like Lego bricks. A great advantage of this method is a straightforward transition between different motion modes, such as switching from trotting to crawling. It is discussed how many different elementary patterns are needed to ensure a stable locomotion control. Finally, in simulation and experiment, it is shown that the robot can master any obstacle course using the proposed locomotion controller.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90237668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper aims to demonstrate the application of control co-design methodology for the rotor blades of a floating offshore wind turbine. A 10 MW reference wind turbine model is utilized in the co-design framework. In this paper, the coupling effect between the system, defined by the pre-cone angle, and the controller, defined by pitch angle, is analyzed with a parametric study. The system parameters of the blade are identified by exciting the system with a step input, and by using the step response. The identified model is used to demonstrate the coupling effects of the structural parameters. The control co-design process is implemented to reduce the blade root bending moment by controlling the pitch angle as a function of the pre-cone angle. Utilizing the 10 MW reference model, the proposed control co-design method can reduce the blade root bending moment and attenuate transverse vibrations faster than the original design. Compared to a sequentially designed controller, the co-design demonstrated reduction of the blade root bending moment with similar attenuation time.
{"title":"Control Co-Design for Rotor Blades of Floating Offshore Wind Turbines","authors":"Xianping Du, L. Burlion, O. Bilgen","doi":"10.1115/IMECE2020-24605","DOIUrl":"https://doi.org/10.1115/IMECE2020-24605","url":null,"abstract":"\u0000 This paper aims to demonstrate the application of control co-design methodology for the rotor blades of a floating offshore wind turbine. A 10 MW reference wind turbine model is utilized in the co-design framework. In this paper, the coupling effect between the system, defined by the pre-cone angle, and the controller, defined by pitch angle, is analyzed with a parametric study. The system parameters of the blade are identified by exciting the system with a step input, and by using the step response. The identified model is used to demonstrate the coupling effects of the structural parameters. The control co-design process is implemented to reduce the blade root bending moment by controlling the pitch angle as a function of the pre-cone angle. Utilizing the 10 MW reference model, the proposed control co-design method can reduce the blade root bending moment and attenuate transverse vibrations faster than the original design. Compared to a sequentially designed controller, the co-design demonstrated reduction of the blade root bending moment with similar attenuation time.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75120592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When a stroller with an infant ride over protrusions or irregularities, vibrations are transmitted from the infant’s lower limb to the upper limb through the tire-frame-cushion. To reduce the load on the infant, the challenge is to reduce the vibration at each part of the infant’s body. To design an equipment for reducing such vibration, it is important to understand the vibration characteristics of infants. Therefore, the purpose of this study was to clarify the vibration characteristics of infants. Transient and frequency response characteristics of the infant–stroller system were investigated by riding over protrusions and irregularities, respectively. In the transient response obtained by both wheels riding over the protrusion, the vibration of the head and chest is a mixture of the primary secondary vibration modes. In the transient response obtained with one wheel riding over the protrusion, the primary vibration mode becomes prominent when the vibration transmitted to the stroller seat is small, and the secondary vibration mode becomes prominent when the vibration transmitted to the stroller seat is large. The frequency response shows some resonance frequencies between 1 Hz and 6 Hz. Vibrations over 8 Hz have small effects on the infants because the acceleration ratio is low at values below 1.
{"title":"Dynamic Characteristics of Infants Riding on Stroller","authors":"Hiroyuki Okajima, S. Ota, R. Ota","doi":"10.1115/IMECE2020-23749","DOIUrl":"https://doi.org/10.1115/IMECE2020-23749","url":null,"abstract":"\u0000 When a stroller with an infant ride over protrusions or irregularities, vibrations are transmitted from the infant’s lower limb to the upper limb through the tire-frame-cushion. To reduce the load on the infant, the challenge is to reduce the vibration at each part of the infant’s body. To design an equipment for reducing such vibration, it is important to understand the vibration characteristics of infants. Therefore, the purpose of this study was to clarify the vibration characteristics of infants. Transient and frequency response characteristics of the infant–stroller system were investigated by riding over protrusions and irregularities, respectively.\u0000 In the transient response obtained by both wheels riding over the protrusion, the vibration of the head and chest is a mixture of the primary secondary vibration modes. In the transient response obtained with one wheel riding over the protrusion, the primary vibration mode becomes prominent when the vibration transmitted to the stroller seat is small, and the secondary vibration mode becomes prominent when the vibration transmitted to the stroller seat is large. The frequency response shows some resonance frequencies between 1 Hz and 6 Hz. Vibrations over 8 Hz have small effects on the infants because the acceleration ratio is low at values below 1.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83110930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Park, HyunYong Lee, Hongryul Ryu, Dongho Kim, Hyun-Soo Kim, Hyesoo Park, Sangryong Lee, H. Yi
The Bottom-mounted ocean-observation platforms installed on the seabed have been used for marine environment analysis. The role of the observing platform is to collect precise observation data without human assistance. However, their working environment is very harsh so the typical device could not afford to provide easy accessibility during their working period. Existing bottom-mounted ocean-observation platforms have been difficult to collect continuous observation data. Therefore, this paper suggests a new ocean-observation platform for precise measurement of the marine environment. Suggested platform uses a PID control method to be applied for error compensation of each axis of gimbal. To verify the system performance, the experiment was carried out in the air with the external force applied to this system.
{"title":"Development of Prototype of Two Axis Gimbal-Type Platform in Underwater","authors":"H. Park, HyunYong Lee, Hongryul Ryu, Dongho Kim, Hyun-Soo Kim, Hyesoo Park, Sangryong Lee, H. Yi","doi":"10.1115/IMECE2020-23661","DOIUrl":"https://doi.org/10.1115/IMECE2020-23661","url":null,"abstract":"\u0000 The Bottom-mounted ocean-observation platforms installed on the seabed have been used for marine environment analysis. The role of the observing platform is to collect precise observation data without human assistance. However, their working environment is very harsh so the typical device could not afford to provide easy accessibility during their working period. Existing bottom-mounted ocean-observation platforms have been difficult to collect continuous observation data. Therefore, this paper suggests a new ocean-observation platform for precise measurement of the marine environment. Suggested platform uses a PID control method to be applied for error compensation of each axis of gimbal. To verify the system performance, the experiment was carried out in the air with the external force applied to this system.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78285648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we utilize the observer/Kalman filter identification (OKID) and the eigensystem realization algorithm (ERA) techniques to identify the modal parameters of a centrifugal machine. To this end, we use an experimental setup to generate a pseudo-impulse input and collect output measurements which are corrupted by noise. We use the pseudo-impulse input and the OKID to find the Markov parameters of the system. Then we form the Hankel matrix of the system and determine the singular values of the system. A minimum-order, state-space model of the system is realized through the Markov parameters and then the natural frequency, damping ratio, mode shapes, and modal amplitudes at the sensor location are estimated by the ERA. We find three models for three separate cases and validate all the three identified models with the measured data and the Waterfall plot. The identified models are useful for designing passive or active vibration suppression control and fault detection systems. The results confirm that OKID/ERA is a reliable time-domain method for identifying the modal parameters of vertical centrifuge machines.
{"title":"An Eigensystem Realization Algorithm for Modal Parameter Identification of a Vertical-Shaft High-Speed Centrifugal Machine","authors":"Sina Piramoon, M. Ayoubi","doi":"10.1115/IMECE2020-23087","DOIUrl":"https://doi.org/10.1115/IMECE2020-23087","url":null,"abstract":"\u0000 In this paper, we utilize the observer/Kalman filter identification (OKID) and the eigensystem realization algorithm (ERA) techniques to identify the modal parameters of a centrifugal machine. To this end, we use an experimental setup to generate a pseudo-impulse input and collect output measurements which are corrupted by noise. We use the pseudo-impulse input and the OKID to find the Markov parameters of the system. Then we form the Hankel matrix of the system and determine the singular values of the system. A minimum-order, state-space model of the system is realized through the Markov parameters and then the natural frequency, damping ratio, mode shapes, and modal amplitudes at the sensor location are estimated by the ERA. We find three models for three separate cases and validate all the three identified models with the measured data and the Waterfall plot. The identified models are useful for designing passive or active vibration suppression control and fault detection systems. The results confirm that OKID/ERA is a reliable time-domain method for identifying the modal parameters of vertical centrifuge machines.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90256012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carlos Fabián Melgarejo Agudelo, John Jairo Blanco Rodriguez, Jessica Gissella Maradey Lázaro
Bearings are the major components in rotary machinery and very used in the industry. The time for bearing failures identification before interrupting operation or affecting product quality is the basis for most predictive maintenance programs. Taking readings, keeping history of failures and evaluating these results in the operation of rotating equipment on a regular basis, allows to detect possible failures before they become catastrophic. In this way, the damages or defects that are detected before a failure occurs, reduce the repair costs and the time that a rotating machine will be inactive. The bearing failures can generate losses due to machine downtime, unwanted vibration, noise and damage of other components, but if they are detected in time, repair costs and downtime are minimal. This article shows in detail the different detection and classification techniques most used to identify bearing failures such as vibration analysis, artificial neural networks (i.e ANN), convolutional neural networks (i.e CNN) and support vector machine (i.e SVM) and the relevant features of each detection technique.
{"title":"Bearing Fault Detection and Classification: A Framework Approach","authors":"Carlos Fabián Melgarejo Agudelo, John Jairo Blanco Rodriguez, Jessica Gissella Maradey Lázaro","doi":"10.1115/IMECE2020-24124","DOIUrl":"https://doi.org/10.1115/IMECE2020-24124","url":null,"abstract":"\u0000 Bearings are the major components in rotary machinery and very used in the industry. The time for bearing failures identification before interrupting operation or affecting product quality is the basis for most predictive maintenance programs. Taking readings, keeping history of failures and evaluating these results in the operation of rotating equipment on a regular basis, allows to detect possible failures before they become catastrophic. In this way, the damages or defects that are detected before a failure occurs, reduce the repair costs and the time that a rotating machine will be inactive. The bearing failures can generate losses due to machine downtime, unwanted vibration, noise and damage of other components, but if they are detected in time, repair costs and downtime are minimal.\u0000 This article shows in detail the different detection and classification techniques most used to identify bearing failures such as vibration analysis, artificial neural networks (i.e ANN), convolutional neural networks (i.e CNN) and support vector machine (i.e SVM) and the relevant features of each detection technique.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76052277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Delays are a common physic effect that is present in a huge quantity of industrial systems with feedback control. Sometimes the impact of the delay presence in a system is neglected without any difference in the performance of the controller. But in some cases, the Delay quantity reaches levels that increase the overshoot significantly or destabilizes the system. For this system the CTCR method can be used to design a “delayed scheduled” controller able to reject the delays effect. To be able to apply this method it is necessary for both the system and the controller to be Linear or linearized. In this article the study case is an articulated inverted pendulum or also called “Pendubot”. This configuration of pendulum was selected because, in spite of being a simple pendulum, it has four equilibrium points, where two equilibrium points were selected to be controlled, the most unstable which has the maximum potential energy for each link and the most stable with the lowest potential energy. The purpose of work with those equilibrium points is compare the difference between the delay rejection in each point with similar setting times and overshoots from controllers. In order to get an accurate model, the state of the current is added along with the viscous friction terms for each joint in the pendulum. To tune the linear and non-linear model an experimental validation was carry on the physical prototype from the Universidad Industrial de Santander (VIE-5373 UIS). The control laws applied were a classical PID and LQR control. Due the controller sample frequency is extremely high in comparison to the states response, all the controllers and linear models were implemented in continuous space. In the first tuning process it was observed that the PID control gets a significantly lowest performance than the LQR control in the unstable equilibrium point, for that reason the comparison between points only was carried on with the LQR equation of feedback system, this can be done in different ways, but for the PID control the Mason theorems was applied and for LQR control only with matrix operation the equation can be obtained. After applying the “Delay scheduling” it was observed that the tuned LQR get a highest delay rejection that PID. An observer fact was that although the controllers for each point have a similar performance the delay pockets have completely different values due the final poles locations for each point. Also was observed that the system only gets one stability pocket, this could because only one delay in the actuator was induced.
{"title":"Delay Scheduling of a LQR and PID Controlled Pendubot Using CTCR Method","authors":"H. S. E. Villegas, C. B. Pinilla, N. Olgaç","doi":"10.1115/IMECE2020-24273","DOIUrl":"https://doi.org/10.1115/IMECE2020-24273","url":null,"abstract":"\u0000 Delays are a common physic effect that is present in a huge quantity of industrial systems with feedback control. Sometimes the impact of the delay presence in a system is neglected without any difference in the performance of the controller. But in some cases, the Delay quantity reaches levels that increase the overshoot significantly or destabilizes the system. For this system the CTCR method can be used to design a “delayed scheduled” controller able to reject the delays effect. To be able to apply this method it is necessary for both the system and the controller to be Linear or linearized. In this article the study case is an articulated inverted pendulum or also called “Pendubot”. This configuration of pendulum was selected because, in spite of being a simple pendulum, it has four equilibrium points, where two equilibrium points were selected to be controlled, the most unstable which has the maximum potential energy for each link and the most stable with the lowest potential energy. The purpose of work with those equilibrium points is compare the difference between the delay rejection in each point with similar setting times and overshoots from controllers. In order to get an accurate model, the state of the current is added along with the viscous friction terms for each joint in the pendulum. To tune the linear and non-linear model an experimental validation was carry on the physical prototype from the Universidad Industrial de Santander (VIE-5373 UIS). The control laws applied were a classical PID and LQR control. Due the controller sample frequency is extremely high in comparison to the states response, all the controllers and linear models were implemented in continuous space. In the first tuning process it was observed that the PID control gets a significantly lowest performance than the LQR control in the unstable equilibrium point, for that reason the comparison between points only was carried on with the LQR equation of feedback system, this can be done in different ways, but for the PID control the Mason theorems was applied and for LQR control only with matrix operation the equation can be obtained. After applying the “Delay scheduling” it was observed that the tuned LQR get a highest delay rejection that PID. An observer fact was that although the controllers for each point have a similar performance the delay pockets have completely different values due the final poles locations for each point. Also was observed that the system only gets one stability pocket, this could because only one delay in the actuator was induced.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81180754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the dynamic behavior of rotating MEMS-based vibratory gyroscopes which employs a thin ring as the vibrating flexible element. The mathematical model for the MEMS ring structure as well as a model for the nonlinear electrostatic excitation forces are formulated. Galerkin’s procedure is employed to reduce the equations of motion to a set of ordinary differential equations. Understanding the effects of nonlinear actuator dynamics is considered important for characterizing the dynamic behavior of such devices. A suitable theoretical model to generate nonlinear electrostatic force that acts on the MEMS ring structure is formulated. Dynamic responses in the driving and the sensing directions are examined via time responses, phase diagram, and Poincare’ map plots when the input angular motion and the nonlinear electrostatic force are considered simultaneously. The analysis is envisaged to aid fabrication of this class of devices as well as for providing design improvements in MEMS Ring-based Gyroscopes.
{"title":"Dynamics of MEMS-Based Angular Rate Sensors Excited via External Electrostatic Forces","authors":"Ibrahim F. Gebrel, Ligang Wang, S. Asokanthan","doi":"10.1115/IMECE2020-24178","DOIUrl":"https://doi.org/10.1115/IMECE2020-24178","url":null,"abstract":"\u0000 This paper investigates the dynamic behavior of rotating MEMS-based vibratory gyroscopes which employs a thin ring as the vibrating flexible element. The mathematical model for the MEMS ring structure as well as a model for the nonlinear electrostatic excitation forces are formulated. Galerkin’s procedure is employed to reduce the equations of motion to a set of ordinary differential equations. Understanding the effects of nonlinear actuator dynamics is considered important for characterizing the dynamic behavior of such devices. A suitable theoretical model to generate nonlinear electrostatic force that acts on the MEMS ring structure is formulated. Dynamic responses in the driving and the sensing directions are examined via time responses, phase diagram, and Poincare’ map plots when the input angular motion and the nonlinear electrostatic force are considered simultaneously. The analysis is envisaged to aid fabrication of this class of devices as well as for providing design improvements in MEMS Ring-based Gyroscopes.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82211501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michal K. Rittikaidachar, Clinton G. Hobart, Jonathon E. Slightam, Jiann-Cherng Su, S. Buerger
We describe the development and benchtop prototype performance characterization of a mechatronic system for automatically drilling small diameter holes of arbitrary depth, to enable monitoring the integrity of oil and gas wells in situ. The precise drilling of very small diameter, high aspect ratio holes, particularly in dimensionally constrained spaces, presents several challenges including bit buckling, limited torsional stiffness, chip clearing, and limited space for the bit and mechanism. We describe a compact mechanism that overcomes these issues by minimizing the unsupported drill bit length throughout the process, enabling the bit to be progressively fed from a chuck as depth increases. When used with flexible drill bits, holes of arbitrary depth and aspect ratio may be drilled orthogonal to the wellbore. The mechanism and a conventional drilling system are tested in deep hole drilling operation. The experimental results show that the system operates as intended and achieves holes with substantially greater aspect ratios than conventional methods with very long drill bits. The mechanism enabled successful drilling of a 1/16″ diameter hole to a depth of 9″, a ratio of 144:1. Dysfunctions prevented drilling of the same hole using conventional methods.
{"title":"Automated Drilling of High Aspect Ratio, Small Diameter Holes in Remote, Confined Spaces","authors":"Michal K. Rittikaidachar, Clinton G. Hobart, Jonathon E. Slightam, Jiann-Cherng Su, S. Buerger","doi":"10.1115/IMECE2020-23904","DOIUrl":"https://doi.org/10.1115/IMECE2020-23904","url":null,"abstract":"\u0000 We describe the development and benchtop prototype performance characterization of a mechatronic system for automatically drilling small diameter holes of arbitrary depth, to enable monitoring the integrity of oil and gas wells in situ. The precise drilling of very small diameter, high aspect ratio holes, particularly in dimensionally constrained spaces, presents several challenges including bit buckling, limited torsional stiffness, chip clearing, and limited space for the bit and mechanism. We describe a compact mechanism that overcomes these issues by minimizing the unsupported drill bit length throughout the process, enabling the bit to be progressively fed from a chuck as depth increases. When used with flexible drill bits, holes of arbitrary depth and aspect ratio may be drilled orthogonal to the wellbore. The mechanism and a conventional drilling system are tested in deep hole drilling operation. The experimental results show that the system operates as intended and achieves holes with substantially greater aspect ratios than conventional methods with very long drill bits. The mechanism enabled successful drilling of a 1/16″ diameter hole to a depth of 9″, a ratio of 144:1. Dysfunctions prevented drilling of the same hole using conventional methods.","PeriodicalId":23585,"journal":{"name":"Volume 7A: Dynamics, Vibration, and Control","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84274752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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