- Thailand
Viboon Sangveraphunsiri
Chulalongkorn University, Mechanical Engineering, Faculty Member
Research Interests:
This paper presents environmental disturbance rejection in a 2-DOF inertial stabilization system by a combination of feedback and feedforward control. For feedback control, sliding mode control and the line of sight (LOS) stabilization... more
This paper presents environmental disturbance rejection in a 2-DOF inertial stabilization system by a combination of feedback and feedforward control. For feedback control, sliding mode control and the line of sight (LOS) stabilization are used for compensation of the nonlinearities, model uncertainties, friction and disturbances from outside environment. Although our mechanisms are carefully designed with statically balance, the center of the gravity will changed due to the configuration change during moving of the gimbal relative to an aerial vehicle. The disturbance torque from unbalance mass and gimbal geometry is unavoidable under the effect of the vibration of the aerial vehicle, which will lead to degrade the systems accuracy. Since the acceleration of the aerial carrier, due to the disturbance torque, can be measured, a feedforward disturbance rejection can be generated to compensate the disturbance torque. The experimental results confirm the validity of the control design procedure for the two-axis gimbaled stabilization system. The proposed controller is capable enough to overcome the disturbances and the impact of LOS disturbances on the tracking performance.
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A simple traction controller was derived from a model following control (MFC) using bilinear transformation. The controller was simplified by adjusting some dynamic parameters. The experiments were conducted to evaluate the validity of... more
A simple traction controller was derived from a model following control (MFC) using bilinear transformation. The controller was simplified by adjusting some dynamic parameters. The experiments were conducted to evaluate the validity of the controller by comparing with the classical PD controller. In the experiments, while the traction controller can prevent slippage, tracking control performance needed to be improved. The feedforward compensation was added to reduce the traction error. The experimentation using the simple controller with feedforward shows that the position error has been reduced while maintaining the traction force between floor and wheels.
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Research Interests:
This paper presents a PC-cluster based multi-camera system for real-time multiple objects tracking. The PC-cluster, a group of linked computers, is developed by using PCI-to-PCI data mover card to improve real-time processing performance... more
This paper presents a PC-cluster based multi-camera system for real-time multiple objects tracking. The PC-cluster, a group of linked computers, is developed by using PCI-to-PCI data mover card to improve real-time processing performance and provide system scalability. Five processing modules have been designed and implemented to control system operations. Target objects are in spherical shape. Four IEEE-1394a cameras with hardwired synchronization are used for system testing. After identifying correspondence objects in different views, 3-D coordinates of each target have been reconstructed. Experimental results show that the system can identify and track multiple objects moving in 3-D space correctly. The maximum frame rate for tracking is 12 frames per second. In the near future, the system can be applied for specific application when additional processing modules are added to the system
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Robot-assisted therapy is a new type of rehabilitation that allows for highly repetitive, intensive, adaptable, and quantifiable physical training. It is increasingly being used to restore motor function, particularly in stroke survivors... more
Robot-assisted therapy is a new type of rehabilitation that allows for highly repetitive, intensive, adaptable, and quantifiable physical training. It is increasingly being used to restore motor function, particularly in stroke survivors with upper limb paresis. The end-effector type robot allows natural movements without complex structure which is ideal for functional rehabilitation training. A 3D end-effector base on a five-bar linkage has been proposed to improve the common end-effector type that covers mechanical design, dynamic control strategy, and application of rehabilitation training or exercise. The dynamic controllers are deweighting with gravity compensation, passive mobilization or active assistive, and the virtual spring-damper wall concept. These controllers are used for developing functional rehabilitation training or exercise from an engineering point of view based on experiences in developing various types of rehabilitation robots. The experiments, based on the performance of the controllers, have been conducted with healthy subjects. The experimental results have shown very promising results and can be extended to various types of functional rehabilitation.
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This paper addresses the relationship between the weight of DC moving-coil permanent-magnet motors and the requirements for the driven motion. The requirements for motion are assumed to be made in terms of a maximum absolute velocity and... more
This paper addresses the relationship between the weight of DC moving-coil permanent-magnet motors and the requirements for the driven motion. The requirements for motion are assumed to be made in terms of a maximum absolute velocity and a maximum absolute acceleration. A move consists of periods of maximum acceleration and periods of maximum velocity, so called trapezoidal velocity profiles. The load on the motor/drive-train is characterized by a maximum torque (or force) which is assumed to occur during a period of maximum acceleration. The DC motor is as~umed to be limited bi a maximu; torque applied magnetically to the armature (essentially a maximum current) and by a maximum armature speed. Within these constraints simple procedures f~r identifying the lightest motors are given. An analysis of several series of popular motors is provided which defines the current state-of-the-art for such motors.
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This work concerns the design and development of a six degrees of freedom haptic device. The haptic device is used as the master arm for internet-based teleoperation purposes. For the experimentation, the Stewarl platform, the other... more
This work concerns the design and development of a six degrees of freedom haptic device. The haptic device is used as the master arm for internet-based teleoperation purposes. For the experimentation, the Stewarl platform, the other parallel mechanism, is used as the slave arm ^ The force reflex from the slave arm is transmitted to the operator through the Tendon-Pulley train of the master arm. Virlual guidance can be implemented in the master arm to improve the maneuverability for the operators. Low ineftia, friction force, and backlash are minimized in the design. Singularity is also eliminated. The inverse and forward kinematics as well as the Jacobian of the master arm are derived. The closed-form solution of the forward kinematics can be obtained by installing 9 encoders, instead of 6. The end-point of the master arm is sent to the slave arrn as commands. The slave arm transforms the commands to joint variables by using the inverse kinematics of the slave arm. The experimental ...
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Tracking an object in three dimensional space is a major issue in computer vision which is normally solved through the extraction of representative features of the object. Two-dimenston coordinates of the series of these image features... more
Tracking an object in three dimensional space is a major issue in computer vision which is normally solved through the extraction of representative features of the object. Two-dimenston coordinates of the series of these image features are used to compute the position of the object. A typical system uses a binocular stereovision system. For an environment with obstruction, two cameras only are not practical, multiple cameras are used instead. When multiple cameras are used, a certain similarity measure among extracted features from any two stereoscopic images helps to match the correspondences. In this way, a three-dimensional measurement can be obtained from the 2-D coordinates of the feafures extracted from the different cameras. In this paper, a multiple cameras system (four cameras) and PC-cluster (two microcomputers) are used for estimating both position and velocity of a specified moving object. Noise filtering and features extraction of images are performed in the PC-cluster ...
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We developed a robot, CUREs (Chulalongkorn University Rehabilitation Robotic Exoskeleton system), for upper extremity rehabilitation. The active assistive control strategy based on the impedance force control is developed and implemented... more
We developed a robot, CUREs (Chulalongkorn University Rehabilitation Robotic Exoskeleton system), for upper extremity rehabilitation. The active assistive control strategy based on the impedance force control is developed and implemented to obtain assistive-resistive paths tracking for rehabilitation activities. The desired trajectory or rehabilitated training pattern for each specific patient need to be assigned first by a medical doctor and a physical therapy. The therapist can program the desired trajectory by guiding the patient arm based on the assigned path pattern and the set of via points will be stored and used for generating the desired trajectory. The desired trajectory will be stored specific for the patient and can be called back anytime. During the rehabilitation, the robot can assist and resist the patient’s arm to follow the desired trajectory. If the patient has difficulty moving his arm to track the desired path, the robot will help by adding more torque to help th...
Research Interests: Engineering and Medicine
A new strategy of robot operation, the bracing strategy, is presented. Under this strategy an arm is moved into position then rigidized by bracing against either the work piece or an auxiliary, static structure. Subsequent precision... more
A new strategy of robot operation, the bracing strategy, is presented. Under this strategy an arm is moved into position then rigidized by bracing against either the work piece or an auxiliary, static structure. Subsequent precision motion does not involve the entire arm, but only ...
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ABSTRACT The paper presents an output tracking technique for a balanced rod inverted pendulum based on computed feedback linearization. For any given trajectory of pendulum, which is the output, the trajectory of rod position, which is... more
ABSTRACT The paper presents an output tracking technique for a balanced rod inverted pendulum based on computed feedback linearization. For any given trajectory of pendulum, which is the output, the trajectory of rod position, which is the internal state, is determined such that the system is input state linearizable without state transformation. Both output and state are used to stabilize and also linearize the system. Once the system is linear, the trajectory control effort can be superimposed such that the system tracks the trajectory. The trajectory control effort is determined from the inverse of the feedback linearized system and thus bounded. In this way, the tracking error is asymptotically decreasing. Both simulation and experiment based on the ECP 505 balanced rod inverted pendulum are used to demonstrate and verify the technique
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Research Interests:
Abstract Background: The American Academy of Dermatology recommends reapplication of sunscreen every two hours for adequate sun protection when outdoor. However, the frequency of reapplication needed to achieve adequate protection in... more
Abstract Background: The American Academy of Dermatology recommends reapplication of sunscreen every two hours for adequate sun protection when outdoor. However, the frequency of reapplication needed to achieve adequate protection in indoor workers remains unknown. Objective: To investigate the persistence of sunscreen applied once in the morning on the face of indoor workers throughout a normal 8-hour workday. Methods: This open-label trial included 20 healthy volunteers who work indoors. Volunteers applied 1 g of sunscreen (2 mg/cm2) mixed with 2% invisible blue fluorescent agent on the face in the morning. Photographs were taken by VISIA-CR booth in UV mode at 8 am and then every 2 hours thereafter until 4 pm with limited outdoor activity less than 1 hour. Six areas of the face were analyzed using digital image analysis software. The primary outcome was the total amount of sunscreen diminution during the 8-hour study period. Results: The amount of sunscreen decreased with mean peak reduction of 16.3% at 2 hours, and minimal reduction thereafter. Total sunscreen reduction was 28.2% at the end of the 8-hour day. Limitations: Small study population. Conclusion: For indoor workers who applied adequate amount of sunscreen once in the morning, reapplication of sunscreen may be unnecessary.
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This paper presents an advanced controller strategy for an inertial stabilization system. The system has a 2-DOF gimbal which will be attached to an aviation vehicle. Motion control of gimbal is a difficult task, mainly because of the... more
This paper presents an advanced controller strategy for an inertial stabilization system. The system has a 2-DOF gimbal which will be attached to an aviation vehicle. Motion control of gimbal is a difficult task, mainly because of the nonlinearities, dynamics modeling errors, friction and disturbances from the outside environment. A gimbaled stabilization system must stabilize the line of sight toward a target against the external motion induced by aviation vehicle maneuvering and aerodynamic forces. So, an advanced controller is needed. Both robust inverse dynamics control and sliding mode control are implemented in the inner loop or gimbal servo-system to control the gimbal motion. Indirect line of sight (LOS) stabilization will be controlled by the outer loop controller. A stabilizer is mounted on the base of the system to measure base rate and orientation of the gimbal in reference to the fixed reference frame. It can withstand high angular slew rates. The experimental results i...
This paper presents an advanced controller strategy for an inertial stabilization system. The system has a 2-DOF gimbal which will be attached to an aviation vehicle. Motion control of gimbal is a difficult task, mainly because of the... more
This paper presents an advanced controller strategy for an inertial stabilization system. The system has a 2-DOF gimbal which will be attached to an aviation vehicle. Motion control of gimbal is a difficult task, mainly because of the nonlinearities, dynamics modeling errors, friction and disturbances from the outside environment. A gimbaled stabilization system must stabilize the line of sight toward a target against the external motion induced by aviation vehicle maneuvering and aerodynamic forces. So, an advanced controller is needed. Both robust inverse dynamics control and sliding mode control are implemented in the inner loop or gimbal servo-system to control the gimbal motion. Indirect line of sight (LOS) stabilization will be controlled by the outer loop controller. A stabilizer is mounted on the base of the system to measure base rate and orientation of the gimbal in reference to the fixed reference frame. It can withstand high angular slew rates. The experimental results i...
Research Interests:
A method for kinematics modeling of a six-wheel Rocker-Bogie mobile robot is described in detail. The forward kinematics is derived by using wheel Jacobian matrices in conjunction with wheel-ground contact angle estimation. Te inverse... more
A method for kinematics modeling of a six-wheel Rocker-Bogie mobile robot is described in detail. The forward kinematics is derived by using wheel Jacobian matrices in conjunction with wheel-ground contact angle estimation. Te inverse kinematics is to obtain the wheel velocities and steering angles from the desired forward velocity and turning rate of the robot. Traction Control also developed to improve traction by comparing information from onboard sensors and wheel velocities to minimize slip of the wheel. Finally, a small robot is built and tested in various conditions of surfaces including vertical obstacle, inclined surface and uneven terrain outdoor condition.
In this paper, we propose a neural network based on our originated two-level adaptive hierarchical clustering algorithm in a preparation process. The preparation process is to manage 3D point clouds by eliminating the effect of the... more
In this paper, we propose a neural network based on our originated two-level adaptive hierarchical clustering algorithm in a preparation process. The preparation process is to manage 3D point clouds by eliminating the effect of the inconsistency and instability of unorganized point clouds, So that the triangular 3D surface models can be correctly obtained from the incremental triangular mesh creation algorithm. We also develop an adaptive self-adjustable connectivity to improve triangular mesh structure. Only one parameter, the edge length of triangle, is needed in the neural network. The proposed two-level algorithm consists of the level for clustering the point clouds that have the same order of limited edge length into the same cluster and the second level for generating a triangular surface model or drape surfaces over the points in the same cluster. The notmal vectors for the generated triangular 3D surfaces model can be obtained from the incremental mesh creation algorithm. Th...
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In this paper, a lower limb rehabilitation robot in sitting position is developed for patients with muscle weakness. The robot is a stationary based type which is able to perform various types of therapeutic exercises. For safe operation,... more
In this paper, a lower limb rehabilitation robot in sitting position is developed for patients with muscle weakness. The robot is a stationary based type which is able to perform various types of therapeutic exercises. For safe operation, the robot's joint is driven by two-stage cable transmission while the balance mechanism is used to reduce actuator size and transmission ratio. Control algorithms for passive, assistive and resistive exercises are designed to match characteristics of each therapeutic exercises and patients with different muscle strength. Preliminary experiments conducted with a healthy subject have demonstrated that the robot and the control algorithms are promising for lower limb rehabilitation task.
Research Interests:
Tracking an object in three dimensional space is a major issue in computer vision which is normally solved through the extraction of representative features of the object. Two-dimenston coordinates of the series of these image features... more
Tracking an object in three dimensional space is a major issue in computer vision which is normally solved through the extraction of representative features of the object. Two-dimenston coordinates of the series of these image features are used to compute the position of the object. A typical system uses a binocular stereovision system. For an environment with obstruction, two cameras only are not practical, multiple cameras are used instead. When multiple cameras are used, a certain similarity measure among extracted features from any two stereoscopic images helps to match the correspondences. In this way, a three-dimensional measurement can be obtained from the 2-D coordinates of the feafures extracted from the different cameras. In this paper, a multiple cameras system (four cameras) and PC-cluster (two microcomputers) are used for estimating both position and velocity of a specified moving object. Noise filtering and features extraction of images are performed in the PC-cluster ...
Research Interests:
This paper presents the derived dynamics equations in 5 axis H-4 parallel manipulator for real-time controls using Inverse Dynamics Control for position control and Impedance Control for indirect force control strategy. Friction models... more
This paper presents the derived dynamics equations in 5 axis H-4 parallel manipulator for real-time controls using Inverse Dynamics Control for position control and Impedance Control for indirect force control strategy. Friction models obtained from the experiment are also used to compensate the actual friction of the control system. From the experimental results of the real-time control, the motion tracking and impedance force control performance are satisfaction. Tracking errors can be reduced within 0.40 millimeter by using friction compensated model. The derived dynamic model is also suitable for others advanced control technique. The accuracy of the control can be improved by increasing the rigidity of the structure.
ABSTRACT Ph.D. Wayne J. Book
Research Interests:
In this research, a real-time multi-camera system has been developed for tracking a moving object in 3-D space. Because of a large amount of data obtained from multiple cameras, a PC-cluster system, a group of linked computers, has been... more
In this research, a real-time multi-camera system has been developed for tracking a moving object in 3-D space. Because of a large amount of data obtained from multiple cameras, a PC-cluster system, a group of linked computers, has been implemented to reduce computational load in one computer and make real-time tracking possible. The system consists of multiple cameras and a PCcluster, four cameras and two PCs in this research. CCD camera is connected to computer via IEEE1394 interface. Synchronization mechanism has been developed using PCI-to-PCI data movers with fiber optic connection. After camera calibration process, a 3-D position of moving object is calculated from a set of corresponding 2-D image coordinates of detected object feature using linear triangulation method. The system has been tested by tracking a spherical object with motion generated by Mitsubishi PA10 robotic arm. The experiment results show that the system can track the object in real-time with acceptable accu...
This paper presents an advanced controller design for an Inertial stabilization system. The system has a 2-DOF gimbal which will be attached to an aviation vehicle. Due to dynamics modeling errors, and friction and disturbances from the... more
This paper presents an advanced controller design for an Inertial stabilization system. The system has a 2-DOF gimbal which will be attached to an aviation vehicle. Due to dynamics modeling errors, and friction and disturbances from the outside environment, the tracking accuracy of an airborne gimbal may severely degrade. So, an advanced controller is needed. Robust inverse dynamics control and the adaptive control are used in the inner loop or gimbal servo-system to control the gimbal motion. An indirect line of sight (LOS) stabilization will be controlled by the outer loop controller. A stabilizer is mounted on the base of the system to measure base rate and orientation of the gimbal in reference to the fixed reference frame. It can withstand high angular slew rates. The experimental results illustrate that the proposed controllers are capable enough to overcome the disturbances and the impact of LOS disturbances on the tracking performance.
Research Interests:
To be presented at Fourth CISM-IFToMM Symposium on Theory and Practice of Robots and Manipulators, Warsaw, Poland, September 8-12, 1981.
This work concerns the design and development of a six degrees of freedom haptic device. The haptic device is used as the master arm for internet-based teleoperation purposes. For the experimentation, the Stewarl platform, the other... more
This work concerns the design and development of a six degrees of freedom haptic device. The haptic device is used as the master arm for internet-based teleoperation purposes. For the experimentation, the Stewarl platform, the other parallel mechanism, is used as the slave arm^ The force reflex from the slave arm is transmitted to the operator through the Tendon-Pulley train of the master arm. Virlual guidance can be implemented in the master arm to improve the maneuverability for the operators. Low ineftia, friction force, and backlash are minimized in the design. Singularity is also eliminated. The inverse and forward kinematics as well as the Jacobian of the master arm are derived. The closed-form solution of the forward kinematics can be obtained by installing 9 encoders, instead of 6. The end-point of the master arm is sent to the slave arrn as commands. The slave arm transforms the commands to joint variables by using the inverse kinematics of the slave arm. The experimental r...
Research Interests:
Research Interests:
A new strategy of robot operation, the bracing strategy, is presented. Under this strategy an arm is moved into position then rigidized by bracing against either the work piece or an auxiliary, static structure. Subsequent precision... more
A new strategy of robot operation, the bracing strategy, is presented. Under this strategy an arm is moved into position then rigidized by bracing against either the work piece or an auxiliary, static structure. Subsequent precision motion does not involve the entire arm, but only degrees of freedom at the end of the arm. The advantage of this strategy is that it allows high speed, precision motion with a light weight, flexible ~rm. Light arms require smaller actuators, less energy, may be faster, are safer, and are less expensive. Four means of clmnping to the structure are considered: A simple norma~ force, mechanical clamping, vacuun attachment, and magnetic attachment. Each means has restrictions and advantages. Arm control with the bracing strategy requires four modes: gross motion control, rendezvous with the bracing structure, control of gross actuators after bracing and control of fine motion actuators distal to the bracing point.
Robots for stroke rehabilitation at the lower limbs in sitting/lying position have been developed extensively. Some of them have been applied in clinics and shown the potential of the recovery of poststroke patients who suffer from... more
Robots for stroke rehabilitation at the lower limbs in sitting/lying position have been developed extensively. Some of them have been applied in clinics and shown the potential of the recovery of poststroke patients who suffer from hemiparesis. These robots were developed to provide training at different joints of lower limbs with various activities and modalities. This article reviews the training activities that were realized by rehabilitation robots in literature, in order to offer insights for developing a novel robot suitable for stroke rehabilitation. The control system of the lower limb rehabilitation robot in sitting position that was introduced in the previous work is discussed in detail to demonstrate the behavior of the robot while training a subject. The nonlinear impedance control law, based on active assistive control strategy, is able to define the response of the robot with more specifications while the passivity property and the robustness of the system is verified....
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In this work, we investigate the measure of isotropy of a manipulator based on its Jacobian matrix. Our manipulator is an exoskeleton arm robot for human physical therapy. An exoskeleton arm robot is wearable robot with joints and links... more
In this work, we investigate the measure of isotropy of a manipulator based on its Jacobian matrix. Our manipulator is an exoskeleton arm robot for human physical therapy. An exoskeleton arm robot is wearable robot with joints and links corresponding to those of the human body. Our goal is to derive dexterity measures called the measure of isotropy which can be used for both design and real-time control of a manipulator. Generally, a dexterity measure must be independent of the scale of a manipulator for design and must be expressed analytically so that it can be used for real-time control. Of course, every dexterity measure must bear a physical meaning.
Research Interests: Engineering and Jacobian
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In this paper, we propose a neural network based on our originated two-level adaptive hierarchical clustering algorithm in a preparation process. The preparation process is to manage 3D point clouds by eliminating the effect of the... more
In this paper, we propose a neural network based on our originated two-level adaptive hierarchical clustering algorithm in a preparation process. The preparation process is to manage 3D point clouds by eliminating the effect of the inconsistency and instability of unorganized point clouds, So that the triangular 3D surface models can be correctly obtained from the incremental triangular mesh creation algorithm. We also develop an adaptive self-adjustable connectivity to improve triangular mesh structure. Only one parameter, the edge length of triangle, is needed in the neural network. The proposed two-level algorithm consists of the level for clustering the point clouds that have the same order of limited edge length into the same cluster and the second level for generating a triangular surface model or drape surfaces over the points in the same cluster. The notmal vectors for the generated triangular 3D surfaces model can be obtained from the incremental mesh creation algorithm. Th...
The development of a 6 DOF Master-Slave Human-Assisted Manipulator Arm with relaxation of kinematics similarity is purposed with experimental results. The Manipulator system consists of a Tendon-Pulley train Master-Arm and the 6 DOF,... more
The development of a 6 DOF Master-Slave Human-Assisted Manipulator Arm with relaxation of kinematics similarity is purposed with experimental results. The Manipulator system consists of a Tendon-Pulley train Master-Arm and the 6 DOF, Chula III, slave arm with five-bar linkage. The maneuverability of the manipulator system is improved by using a virtual guidance and position gain (p G). The virtual guidance, implement in the Master Arm, will improve the maneuverability for the operators, while the p G will improve the accuracy of position and orientations of the system. The experimental results shown that the operator with virtual guidance can control the slave arm very effective. The accuracy of positions and orientations will depends on the gain p G , used for the path generation, which is the gain for amplifying the error signals of the master and slave system.
A method for kinematics modeling of a six-wheel Rocker-Bogie mobile robot is described in detail. The forward kinematics is derived by using wheel Jacobian matrices in conjunction with wheel-ground contact angle estimation. Te inverse... more
A method for kinematics modeling of a six-wheel Rocker-Bogie mobile robot is described in detail. The forward kinematics is derived by using wheel Jacobian matrices in conjunction with wheel-ground contact angle estimation. Te inverse kinematics is to obtain the wheel velocities and steering angles from the desired forward velocity and turning rate of the robot. Traction Control also developed to improve traction by comparing information from onboard sensors and wheel velocities to minimize slip of the wheel. Finally, a small robot is built and tested in various conditions of surfaces including vertical obstacle, inclined surface and uneven terrain outdoor condition.
ABSTRACT Ph.D. Wayne J. Book
This paper presents an advanced controller design for an Inertial stabilization system. The system has a 2-DOF gimbal which will be attached to an aviation vehicle. Due to dynamics modeling errors, and friction and disturbances from the... more
This paper presents an advanced controller design for an Inertial stabilization system. The system has a 2-DOF gimbal which will be attached to an aviation vehicle. Due to dynamics modeling errors, and friction and disturbances from the outside environment, the tracking accuracy of an airborne gimbal may severely degrade. So, an advanced controller is needed. A robust inverse dynamics control and the adaptive control are used in the inner loop or gimbal servo-system to control the gimbal motion. An indirect line of sight (LOS) stabilization will be controlled by the outer loop controller. A stabilizer is mounted on the base of the system to measure base rate and orientation of the gimbal in reference to the fixed reference frame. It can withstand high angular slew rates. The experimental results illustrate that the proposed controllers are capable enough to overcome the disturbances and the impact of LOS disturbances on the tracking performance. Surveying of forest resources, and fl...