Ocean Power Technologies (OPT) designs and builds wave energy converters (WECs) under the brand n... more Ocean Power Technologies (OPT) designs and builds wave energy converters (WECs) under the brand name PowerBuoy to generate electrical power from ocean waves. An important component of assessing a candidate application is predicting the amount of generated power, which requires information about the deployment site wave climate. Historically, OPT has used a joint probability distribution of wave height and period based on an idealized spectral shape with the statistics for the bin center, but a more realistic spectral description has been shown to improve power predictions. While OPT can estimate power by running a simulation for every hourly spectrum in a multiyear timeseries, a more compact spectral representation is sought. Here measured spectra with similar statistics are averaged and used as prediction inputs; the results are compared to predictions based on idealized spectra. To gain insight into how prediction quality might depend on device resonant period or site dominant per...
Transactions of the Canadian Society for Mechanical Engineering
The Lagrangian approach to the development of dynamics equations for a multi-body system, constra... more The Lagrangian approach to the development of dynamics equations for a multi-body system, constrained or otherwise, requires solving the forward kinematics of the system at velocity level in order to derive the kinetic energy of the system. The kinetic-energy expression should then be differentiated multiple times to derive the equations of motion of the system. Among these differentiations, the partial derivative of kinetic energy with respect to the system generalized coordinates is specially cumbersome. In this paper, we will derive this partial derivative using a novel kinematic relation for the partial derivative of angular velocity with respect to the system generalized coordinates. It will be shown that, as a result of the use of this relation, the equations of motion of the system are directly derived in the form of Kane’s equations.
2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2006
This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conve... more This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conventional reconfigurable robots, our design does not achieve reconfigurability by utilizing modular joints. Rather, the robot is equipped with passive joints, i.e., joints with no actuator or sensor, which permit changing the Denavit-Hartenberg parameters such as the link length and twist angle. The passive joints will
International Conference on Intelligent RObots and Systems - IROS, 2008
This paper is focused on an adaptive vision system for the guidance of a robot to intercept a non... more This paper is focused on an adaptive vision system for the guidance of a robot to intercept a non-cooperative target satellite with unknown dynamics parameters. A Kalman filter is developed to reliably estimate the states of the object as well as all of its inertial parameters - namely, the moment-of-inertia ratios, the center-of-mass location, and the orientation of the principle
Many demonstration missions such as Orbital Ex- press, DART, XSS-11, TECSAS, and the possible rob... more Many demonstration missions such as Orbital Ex- press, DART, XSS-11, TECSAS, and the possible robotic servicing/decomissioning of Hubble have re- cently been planned. A common, important element to many of these missions is the necessity of me- chanically interfacing the spacecrafts involved. The Canadian Space Agency targets the utilization of a hardware-in-the-loop simulation (HLS) to emulate the satellite-docking procedure. This
Proceedings 2007 IEEE International Conference on Robotics and Automation, 2007
The advantages of reconfigurable robots have been discussed in the specialized literature. Conven... more The advantages of reconfigurable robots have been discussed in the specialized literature. Conventionally, reconfigurability was a direct result of using modular joints. In this paper we discuss the configuration control and recalibration of a different class of reconfigurable robots, one which is equipped with lockable cylindrical joints with no actuators or sensors. Such a robot can be as versatile and
2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2006
This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conve... more This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conventional reconfigurable robots, our design does not achieve reconfigurability by utilizing modular joints. Rather, the robot is equipped with passive joints, i.e., joints with no actuator or sensor, which permit changing the Denavit-Hartenberg parameters such as the link length and twist angle. The passive joints will
Ocean Power Technologies (OPT) designs and builds wave energy converters (WECs) under the brand n... more Ocean Power Technologies (OPT) designs and builds wave energy converters (WECs) under the brand name PowerBuoy to generate electrical power from ocean waves. An important component of assessing a candidate application is predicting the amount of generated power, which requires information about the deployment site wave climate. Historically, OPT has used a joint probability distribution of wave height and period based on an idealized spectral shape with the statistics for the bin center, but a more realistic spectral description has been shown to improve power predictions. While OPT can estimate power by running a simulation for every hourly spectrum in a multiyear timeseries, a more compact spectral representation is sought. Here measured spectra with similar statistics are averaged and used as prediction inputs; the results are compared to predictions based on idealized spectra. To gain insight into how prediction quality might depend on device resonant period or site dominant per...
Transactions of the Canadian Society for Mechanical Engineering
The Lagrangian approach to the development of dynamics equations for a multi-body system, constra... more The Lagrangian approach to the development of dynamics equations for a multi-body system, constrained or otherwise, requires solving the forward kinematics of the system at velocity level in order to derive the kinetic energy of the system. The kinetic-energy expression should then be differentiated multiple times to derive the equations of motion of the system. Among these differentiations, the partial derivative of kinetic energy with respect to the system generalized coordinates is specially cumbersome. In this paper, we will derive this partial derivative using a novel kinematic relation for the partial derivative of angular velocity with respect to the system generalized coordinates. It will be shown that, as a result of the use of this relation, the equations of motion of the system are directly derived in the form of Kane’s equations.
2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2006
This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conve... more This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conventional reconfigurable robots, our design does not achieve reconfigurability by utilizing modular joints. Rather, the robot is equipped with passive joints, i.e., joints with no actuator or sensor, which permit changing the Denavit-Hartenberg parameters such as the link length and twist angle. The passive joints will
International Conference on Intelligent RObots and Systems - IROS, 2008
This paper is focused on an adaptive vision system for the guidance of a robot to intercept a non... more This paper is focused on an adaptive vision system for the guidance of a robot to intercept a non-cooperative target satellite with unknown dynamics parameters. A Kalman filter is developed to reliably estimate the states of the object as well as all of its inertial parameters - namely, the moment-of-inertia ratios, the center-of-mass location, and the orientation of the principle
Many demonstration missions such as Orbital Ex- press, DART, XSS-11, TECSAS, and the possible rob... more Many demonstration missions such as Orbital Ex- press, DART, XSS-11, TECSAS, and the possible robotic servicing/decomissioning of Hubble have re- cently been planned. A common, important element to many of these missions is the necessity of me- chanically interfacing the spacecrafts involved. The Canadian Space Agency targets the utilization of a hardware-in-the-loop simulation (HLS) to emulate the satellite-docking procedure. This
Proceedings 2007 IEEE International Conference on Robotics and Automation, 2007
The advantages of reconfigurable robots have been discussed in the specialized literature. Conven... more The advantages of reconfigurable robots have been discussed in the specialized literature. Conventionally, reconfigurability was a direct result of using modular joints. In this paper we discuss the configuration control and recalibration of a different class of reconfigurable robots, one which is equipped with lockable cylindrical joints with no actuators or sensors. Such a robot can be as versatile and
2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2006
This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conve... more This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conventional reconfigurable robots, our design does not achieve reconfigurability by utilizing modular joints. Rather, the robot is equipped with passive joints, i.e., joints with no actuator or sensor, which permit changing the Denavit-Hartenberg parameters such as the link length and twist angle. The passive joints will
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Papers by Kourosh Parsa