[1993] Proceedings IEEE International Conference on Robotics and Automation
This paper proposes a hybrid position/force controller for flexible link manipulators that make c... more This paper proposes a hybrid position/force controller for flexible link manipulators that make contact with the environment at more than one point. The necessity for such a controller can be found in controlling a flexible bracing manipulator.
nertial force damping control by micro-manipulator modulation is proposed to suppress the vibrati... more nertial force damping control by micro-manipulator modulation is proposed to suppress the vibrations of a micro/macro manipulator system. The damping controller, developed using classical control theory, is added to the existing control system. Real-time measurements of macro-manipulator flexibility are used to adjust the motion of the micro-manipulator to counteract structural vibrations. Experimental studies using an existing micro/macro flexiblelink manipulator testbed (shown in Fig. 1) demonstrate the effectiveness of the proposed control scheme for both vertical and horizontal plane vibration.
Roll angle and height of the center of gravity are important variables that play a critical role ... more Roll angle and height of the center of gravity are important variables that play a critical role in the calculation of real-time rollover index for a vehicle. The rollover index predicts the real-time propensity for rollover and is used in activation of rollover prevention systems such as differential braking based stability control systems. Sensors to measure roll angle are expensive. Sensors to estimate the c.g. height of a vehicle do not exist. While the height of the center-of-gravity does not change in real-time, it does change with the number of passengers and loading of the vehicle. This paper focuses on algorithms to estimate roll angle and c.g. height. The algorithms investigated include a sensor fusion algorithm that utilizes a low frequency tilt angle sensor and a gyroscope and a dynamic observer that utilizes only a lateral accelerometer and a gyroscope. The performance of the developed algorithms is investigated using simulations and experimental tests. Experimental data confirm that the developed algorithms perform reliably in a number of different maneuvers that include constant steering, ramp steering, double lane change and sine with dwell steering tests.
This paper focuses on the concept of utilizing torque-biasing systems on a four-wheel drive vehic... more This paper focuses on the concept of utilizing torque-biasing systems on a four-wheel drive vehicle for improving vehicle stability and handling performance. In contrast to brake-based yaw stability control systems, torque biasing has the potential to provide yaw stability control without slowing down the longitudinal response of the vehicle. An inexpensive system configuration is considered in which the driveline is
Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999
Introduces an active damping control scheme for a robotic manipulator attached to a compliant bas... more Introduces an active damping control scheme for a robotic manipulator attached to a compliant base. By applying the proposed control, the manipulator generates its inertial force to compensate for base oscillation while following a desired position. The control scheme uses acceleration feedback and one-sample delayed torque to decouple the system, and then computes the fast and slow controller for rigid body motion and base oscillation based on two-time scale theory. A computer simulation study shows very promising results for a test bed consisting of a two-link manipulator and a compliant base in XY motion
An articulated aerial work platform is a type of off highway vehicle with a long/flexible beam to... more An articulated aerial work platform is a type of off highway vehicle with a long/flexible beam to provide temporary access to inaccessable areas. The motivation of the research is to improve productivity and safety of the work platform via advanced control schemes. In this paper, a motion control architecture is presented for trajectory tracking and vibration suppression. By using the sensors integrated in hydraulic power elements, a closed loop coordinated control is presented to allow the end effector of the work platform to track a desired trajectory, thus alleviating the demand on operators' proficiency and improving productivity. In order to reduce the tracking error caused by the beam deflection, a Static Deflection Compensation Controller has been developed. In terms of vehicle safety, it has been observed that vibration associated with the long beam is significant, and the vibration characteristics change according to vehicle geometry. A unique input shaper is presented with the two impulses and the time varying parameters. The benefits are gaining robustness with respect to geometric variation, as well as reducing time delay for better responsiveness. The experimental study validates the controller.
ABSTRACT This paper focuses on modeling of torque-biasing devices of a four-wheel-drive system us... more ABSTRACT This paper focuses on modeling of torque-biasing devices of a four-wheel-drive system used for improving vehicle stability and handling performance. The proposed driveline system is based on nominal frontwheel-drive operation with on-demand transfer ...
Proceedings of the 2003 American Control Conference, 2003.
In this paper, modeling and nonlinear controller design for an omni-directional mobile robot are ... more In this paper, modeling and nonlinear controller design for an omni-directional mobile robot are presented. Based on the robot dynamics model, a nonlinear controller is designed using the Trajectory Linearization Control (TLC) method. Some simulation results of the controller are presented.
Proceedings 15th International Parallel and Distributed Processing Symposium. IPDPS 2001
This paper describes a test-bed for technology that unifies agent based computing and adaptive re... more This paper describes a test-bed for technology that unifies agent based computing and adaptive resource management for dynamic real-time systems. We describe a unified framework that combines a hybrid agent based architecture with explicit resource adapting mechanisms.
Journal of Dynamic Systems, Measurement, and Control, 2006
We consider the problems of kinematic and dynamic constraints, with actuator saturation and wheel... more We consider the problems of kinematic and dynamic constraints, with actuator saturation and wheel slippage avoidance, for motion planning of a holonomic three-wheeled omni-directional robot. That is, the motion planner must not demand more velocity and acceleration at each time instant than the robot can provide. A new coupled non-linear dynamics model is derived. The novel concepts of Velocity and Acceleration Cones are proposed for determining the kinematic and dynamic constraints. The Velocity Cone is based on kinematics; we propose two Acceleration Cones, one for avoiding actuator saturation and the other for avoiding wheel slippage. The wheel slippage Acceleration Cone was found to dominate. In practical motion, all commanded velocities and accelerations from the motion planner must lie within these cones for successful motion. Case studies, simulations, and experimental validations are presented for our dynamic model and controller, plus the Velocity and Acceleration Cones.
ABSTRACT It has long been recognized in the automotive research community that knowledge of the r... more ABSTRACT It has long been recognized in the automotive research community that knowledge of the real-time tire-road friction coefficient can be extremely valuable for active safety applications, including traction control, yaw stability control and rollover prevention. Previous research results in literature have focused on estimation of average friction coefficient for the vehicle or on average friction coefficient for both drive wheels of the vehicle. This paper explores the development of algorithms for reliable estimation of friction coefficient at each individual wheel of the vehicle. Three different algorithms are proposed based on the types of sensors available - one that utilizes engine torque, brake torque and GPS measurements, one that utilizes torque measurements and an accelerometer and one that utilizes GPS measurements and an accelerometer. These algorithms are first evaluated in simulation and then evaluated experimentally on a Volvo XC90 sport utility vehicle. Experimental results demonstrate that friction coefficients at the individual wheels and road gradient can both be estimated reliably. Individual wheel friction measurements are expected to be more valuable for active safety systems than average friction measurements
IEEE Transactions on Intelligent Transportation Systems, 2011
In active rollover prevention systems, a real-time rollover index, which indicates the likelihood... more In active rollover prevention systems, a real-time rollover index, which indicates the likelihood of the vehicle to roll over, is used. This paper focuses on state and parameter estimation for reliable computation of the rollover index. Two key variables that are difficult to measure and play a critical role in the rollover index are found to be the roll angle and the height of the center of gravity of the vehicle. Algorithms are developed for real-time estimation of these variables. The algorithms investigated include a sensor fusion algorithm and a nonlinear dynamic observer. The sensor fusion algorithm requires a low-frequency tilt-angle sensor, whereas the dynamic observer utilizes only a lateral accelerometer and a gyroscope. The stability of the nonlinear observer is shown using Lyapunov's indirect method. The performance of the developed algorithms is investigated using simulations and experimental tests. Experimental data confirm that the developed algorithms perform reliably in a number of different maneuvers that include constant steering, ramp steering, double lane change, and sine with dwell steering tests.
IEEE Transactions on Control Systems Technology, 2009
Real-time knowledge of the slip angle in a vehicle is useful in many active vehicle safety applic... more Real-time knowledge of the slip angle in a vehicle is useful in many active vehicle safety applications, including yaw stability control, rollover prevention, and lane departure avoidance. Sensors to measure slip angle, including two-antenna GPS systems and optical sensors, are too expensive for ordinary automotive applications. This paper develops a real-time algorithm for estimation of slip angle using inexpensive sensors normally available for yaw stability control applications. The algorithm utilizes a combination of model-based estimation and kinematics-based estimation. Compared with previously published results on slip angle estimation, this present paper compensates for the presence of road bank angle and variations in tire-road characteristics. The developed algorithm is evaluated through experimental tests on a Volvo XC90 sport utility vehicle. Detailed experimental results show that the developed system can reliably estimate slip angle for a variety of test maneuvers.
IEEE Transactions on Control Systems Technology, 2007
This brief paper focuses on the concept of utilizing torque-biasing systems on a four-wheel drive... more This brief paper focuses on the concept of utilizing torque-biasing systems on a four-wheel drive vehicle for improving vehicle stability and handling performance. In contrast to brakebased yaw stability control systems, torque biasing has the potential to provide yaw stability control without slowing down the longitudinal response of the vehicle. An inexpensive system configuration is considered in which the driveline is based on front-wheel drive with on-demand transfer of torque to the rear. The torque-biasing components of the system are an electronically controlled center coupler and a rear electronically controlled limited slip differential. First, modeling of the torque-biasing devices is briefly introduced. Then, a hierarchical control architecture is presented in which an upper controller determines desired yaw moment for achieving yaw rate and slip angle control. The lower controller attempts to achieve the desired yaw moment using torque biasing. Theoretical analysis shows that transfer of longitudinal tire forces can effectively be used to achieve any desired yaw moment for the vehicle. However, the use of torque biasing cannot always achieve the desired transfer of longitudinal tire forces. Simulations show that the proposed control system can always effectively provide understeering yaw moments but can provide oversteering torque moments only during on-throttle maneuvers. Experimental data show that significant stability improvements are obtained using the proposed system for low-friction slalom maneuvers and a T-junction launch maneuver. The results presented in this brief shed important light on the possibilities and limitations of using torque biasing for vehicle yaw stability control.
... [4] Lee,HH, Modeling and control of a Three-Dimensional Overhead Crane. Journal of Dynamic Sy... more ... [4] Lee,HH, Modeling and control of a Three-Dimensional Overhead Crane. Journal of Dynamic Systems, Measurement and Control.1998. [5] John T. Wen, Dan O. Popa, Gustavo Montemyor and Perter L. Liu, Human Assisted Impedance Control of Overhead Cranes. ...
... Brian Carter 1 , Matt Good 1 , Mike Dorohoff 1 , Jae Lew 1 , Robert L. Williams II 1 , Paolo ... more ... Brian Carter 1 , Matt Good 1 , Mike Dorohoff 1 , Jae Lew 1 , Robert L. Williams II 1 , Paolo Gallina 2 1 Department of Mechanical Engineering Ohio University, USA 2 Department of Innovation in Mechanics and Management ... [3] SL Dickerson and BD Lapin, 1991, Control of an ...
[1993] Proceedings IEEE International Conference on Robotics and Automation
This paper proposes a hybrid position/force controller for flexible link manipulators that make c... more This paper proposes a hybrid position/force controller for flexible link manipulators that make contact with the environment at more than one point. The necessity for such a controller can be found in controlling a flexible bracing manipulator.
nertial force damping control by micro-manipulator modulation is proposed to suppress the vibrati... more nertial force damping control by micro-manipulator modulation is proposed to suppress the vibrations of a micro/macro manipulator system. The damping controller, developed using classical control theory, is added to the existing control system. Real-time measurements of macro-manipulator flexibility are used to adjust the motion of the micro-manipulator to counteract structural vibrations. Experimental studies using an existing micro/macro flexiblelink manipulator testbed (shown in Fig. 1) demonstrate the effectiveness of the proposed control scheme for both vertical and horizontal plane vibration.
Roll angle and height of the center of gravity are important variables that play a critical role ... more Roll angle and height of the center of gravity are important variables that play a critical role in the calculation of real-time rollover index for a vehicle. The rollover index predicts the real-time propensity for rollover and is used in activation of rollover prevention systems such as differential braking based stability control systems. Sensors to measure roll angle are expensive. Sensors to estimate the c.g. height of a vehicle do not exist. While the height of the center-of-gravity does not change in real-time, it does change with the number of passengers and loading of the vehicle. This paper focuses on algorithms to estimate roll angle and c.g. height. The algorithms investigated include a sensor fusion algorithm that utilizes a low frequency tilt angle sensor and a gyroscope and a dynamic observer that utilizes only a lateral accelerometer and a gyroscope. The performance of the developed algorithms is investigated using simulations and experimental tests. Experimental data confirm that the developed algorithms perform reliably in a number of different maneuvers that include constant steering, ramp steering, double lane change and sine with dwell steering tests.
This paper focuses on the concept of utilizing torque-biasing systems on a four-wheel drive vehic... more This paper focuses on the concept of utilizing torque-biasing systems on a four-wheel drive vehicle for improving vehicle stability and handling performance. In contrast to brake-based yaw stability control systems, torque biasing has the potential to provide yaw stability control without slowing down the longitudinal response of the vehicle. An inexpensive system configuration is considered in which the driveline is
Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999
Introduces an active damping control scheme for a robotic manipulator attached to a compliant bas... more Introduces an active damping control scheme for a robotic manipulator attached to a compliant base. By applying the proposed control, the manipulator generates its inertial force to compensate for base oscillation while following a desired position. The control scheme uses acceleration feedback and one-sample delayed torque to decouple the system, and then computes the fast and slow controller for rigid body motion and base oscillation based on two-time scale theory. A computer simulation study shows very promising results for a test bed consisting of a two-link manipulator and a compliant base in XY motion
An articulated aerial work platform is a type of off highway vehicle with a long/flexible beam to... more An articulated aerial work platform is a type of off highway vehicle with a long/flexible beam to provide temporary access to inaccessable areas. The motivation of the research is to improve productivity and safety of the work platform via advanced control schemes. In this paper, a motion control architecture is presented for trajectory tracking and vibration suppression. By using the sensors integrated in hydraulic power elements, a closed loop coordinated control is presented to allow the end effector of the work platform to track a desired trajectory, thus alleviating the demand on operators' proficiency and improving productivity. In order to reduce the tracking error caused by the beam deflection, a Static Deflection Compensation Controller has been developed. In terms of vehicle safety, it has been observed that vibration associated with the long beam is significant, and the vibration characteristics change according to vehicle geometry. A unique input shaper is presented with the two impulses and the time varying parameters. The benefits are gaining robustness with respect to geometric variation, as well as reducing time delay for better responsiveness. The experimental study validates the controller.
ABSTRACT This paper focuses on modeling of torque-biasing devices of a four-wheel-drive system us... more ABSTRACT This paper focuses on modeling of torque-biasing devices of a four-wheel-drive system used for improving vehicle stability and handling performance. The proposed driveline system is based on nominal frontwheel-drive operation with on-demand transfer ...
Proceedings of the 2003 American Control Conference, 2003.
In this paper, modeling and nonlinear controller design for an omni-directional mobile robot are ... more In this paper, modeling and nonlinear controller design for an omni-directional mobile robot are presented. Based on the robot dynamics model, a nonlinear controller is designed using the Trajectory Linearization Control (TLC) method. Some simulation results of the controller are presented.
Proceedings 15th International Parallel and Distributed Processing Symposium. IPDPS 2001
This paper describes a test-bed for technology that unifies agent based computing and adaptive re... more This paper describes a test-bed for technology that unifies agent based computing and adaptive resource management for dynamic real-time systems. We describe a unified framework that combines a hybrid agent based architecture with explicit resource adapting mechanisms.
Journal of Dynamic Systems, Measurement, and Control, 2006
We consider the problems of kinematic and dynamic constraints, with actuator saturation and wheel... more We consider the problems of kinematic and dynamic constraints, with actuator saturation and wheel slippage avoidance, for motion planning of a holonomic three-wheeled omni-directional robot. That is, the motion planner must not demand more velocity and acceleration at each time instant than the robot can provide. A new coupled non-linear dynamics model is derived. The novel concepts of Velocity and Acceleration Cones are proposed for determining the kinematic and dynamic constraints. The Velocity Cone is based on kinematics; we propose two Acceleration Cones, one for avoiding actuator saturation and the other for avoiding wheel slippage. The wheel slippage Acceleration Cone was found to dominate. In practical motion, all commanded velocities and accelerations from the motion planner must lie within these cones for successful motion. Case studies, simulations, and experimental validations are presented for our dynamic model and controller, plus the Velocity and Acceleration Cones.
ABSTRACT It has long been recognized in the automotive research community that knowledge of the r... more ABSTRACT It has long been recognized in the automotive research community that knowledge of the real-time tire-road friction coefficient can be extremely valuable for active safety applications, including traction control, yaw stability control and rollover prevention. Previous research results in literature have focused on estimation of average friction coefficient for the vehicle or on average friction coefficient for both drive wheels of the vehicle. This paper explores the development of algorithms for reliable estimation of friction coefficient at each individual wheel of the vehicle. Three different algorithms are proposed based on the types of sensors available - one that utilizes engine torque, brake torque and GPS measurements, one that utilizes torque measurements and an accelerometer and one that utilizes GPS measurements and an accelerometer. These algorithms are first evaluated in simulation and then evaluated experimentally on a Volvo XC90 sport utility vehicle. Experimental results demonstrate that friction coefficients at the individual wheels and road gradient can both be estimated reliably. Individual wheel friction measurements are expected to be more valuable for active safety systems than average friction measurements
IEEE Transactions on Intelligent Transportation Systems, 2011
In active rollover prevention systems, a real-time rollover index, which indicates the likelihood... more In active rollover prevention systems, a real-time rollover index, which indicates the likelihood of the vehicle to roll over, is used. This paper focuses on state and parameter estimation for reliable computation of the rollover index. Two key variables that are difficult to measure and play a critical role in the rollover index are found to be the roll angle and the height of the center of gravity of the vehicle. Algorithms are developed for real-time estimation of these variables. The algorithms investigated include a sensor fusion algorithm and a nonlinear dynamic observer. The sensor fusion algorithm requires a low-frequency tilt-angle sensor, whereas the dynamic observer utilizes only a lateral accelerometer and a gyroscope. The stability of the nonlinear observer is shown using Lyapunov's indirect method. The performance of the developed algorithms is investigated using simulations and experimental tests. Experimental data confirm that the developed algorithms perform reliably in a number of different maneuvers that include constant steering, ramp steering, double lane change, and sine with dwell steering tests.
IEEE Transactions on Control Systems Technology, 2009
Real-time knowledge of the slip angle in a vehicle is useful in many active vehicle safety applic... more Real-time knowledge of the slip angle in a vehicle is useful in many active vehicle safety applications, including yaw stability control, rollover prevention, and lane departure avoidance. Sensors to measure slip angle, including two-antenna GPS systems and optical sensors, are too expensive for ordinary automotive applications. This paper develops a real-time algorithm for estimation of slip angle using inexpensive sensors normally available for yaw stability control applications. The algorithm utilizes a combination of model-based estimation and kinematics-based estimation. Compared with previously published results on slip angle estimation, this present paper compensates for the presence of road bank angle and variations in tire-road characteristics. The developed algorithm is evaluated through experimental tests on a Volvo XC90 sport utility vehicle. Detailed experimental results show that the developed system can reliably estimate slip angle for a variety of test maneuvers.
IEEE Transactions on Control Systems Technology, 2007
This brief paper focuses on the concept of utilizing torque-biasing systems on a four-wheel drive... more This brief paper focuses on the concept of utilizing torque-biasing systems on a four-wheel drive vehicle for improving vehicle stability and handling performance. In contrast to brakebased yaw stability control systems, torque biasing has the potential to provide yaw stability control without slowing down the longitudinal response of the vehicle. An inexpensive system configuration is considered in which the driveline is based on front-wheel drive with on-demand transfer of torque to the rear. The torque-biasing components of the system are an electronically controlled center coupler and a rear electronically controlled limited slip differential. First, modeling of the torque-biasing devices is briefly introduced. Then, a hierarchical control architecture is presented in which an upper controller determines desired yaw moment for achieving yaw rate and slip angle control. The lower controller attempts to achieve the desired yaw moment using torque biasing. Theoretical analysis shows that transfer of longitudinal tire forces can effectively be used to achieve any desired yaw moment for the vehicle. However, the use of torque biasing cannot always achieve the desired transfer of longitudinal tire forces. Simulations show that the proposed control system can always effectively provide understeering yaw moments but can provide oversteering torque moments only during on-throttle maneuvers. Experimental data show that significant stability improvements are obtained using the proposed system for low-friction slalom maneuvers and a T-junction launch maneuver. The results presented in this brief shed important light on the possibilities and limitations of using torque biasing for vehicle yaw stability control.
... [4] Lee,HH, Modeling and control of a Three-Dimensional Overhead Crane. Journal of Dynamic Sy... more ... [4] Lee,HH, Modeling and control of a Three-Dimensional Overhead Crane. Journal of Dynamic Systems, Measurement and Control.1998. [5] John T. Wen, Dan O. Popa, Gustavo Montemyor and Perter L. Liu, Human Assisted Impedance Control of Overhead Cranes. ...
... Brian Carter 1 , Matt Good 1 , Mike Dorohoff 1 , Jae Lew 1 , Robert L. Williams II 1 , Paolo ... more ... Brian Carter 1 , Matt Good 1 , Mike Dorohoff 1 , Jae Lew 1 , Robert L. Williams II 1 , Paolo Gallina 2 1 Department of Mechanical Engineering Ohio University, USA 2 Department of Innovation in Mechanics and Management ... [3] SL Dickerson and BD Lapin, 1991, Control of an ...
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