Hamed Rahimi Nohooji | Curtin University (original) (raw)

Papers by Hamed Rahimi Nohooji

Research Square (Research Square), Dec 4, 2023

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Sciyo eBooks, Aug 12, 2010

ABSTRACT

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IEEE Access

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Journal of Mechanisms and Robotics, 2022

This paper proposed a systematic framework to automatically design and fabricate optimized soft r... more This paper proposed a systematic framework to automatically design and fabricate optimized soft robotic fingers. The soft finger is composed of a soft silicone structure with inner air chambers and a harder outer layer, which are fabricated by molding process and 3D printing, respectively. The softer layer is utilized for actuation while the supportive hard structure is used to impose constraints. The framework applies a topology optimization approach based on rational approximation of material properties (RAMP) method to obtain an optimal design of the outer layer of the soft fingers. Two basic motion primitives (bending and twisting) of the soft finger were explored. A multi-segmented soft bending finger and a soft twisting finger were designed and fabricated through the proposed framework. This work also explored the combination of bending and twisting primitives by developing a combined bending-twisting soft finger. The soft fingers were characterized by free and blocked movemen...

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This paper is concerned with the dynamic motion analysis and the planning of maximum payload path... more This paper is concerned with the dynamic motion analysis and the planning of maximum payload path of flexible manipulators. The finite element method was employed for dynamic modelling of the system and the motion of the model was considered as a combination of the rigid displacement and the elastic deformation of each link. Each manipulator link was treated as a finite number of elements and total displacement was derived by means of the shape functions of flexible elements. The problem of maximum payload trajectory planning was formulated as an optimal control problem. An indirect optimal control solution was employed. This method converts an optimality problem to a twopoint boundary value problem. The effect of the number of elements on the dynamic motion, optimal trajectory and maximum allowable dynamic payload of the system was studied. Finally, a number of simulations were performed to verify the applicability and capability of the method for the nonlinear dynamic modelling an...

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Robot-assisted therapy can improve motor function in patients recovering from stroke. Assist-as-n... more Robot-assisted therapy can improve motor function in patients recovering from stroke. Assist-as-needed algorithms provide only minimal robotic assistance in the therapy, thus requiring significant effort from the impaired subject. This paper presents an adaptive neural assist-as-needed controller for rehabilitative robots. The controller combines the Lyapunov direct method with the computed torque control and neural networks. Robot assistance is limited to only as needed by adding the force reducing term into the adaptive control law. This paper shows that by the presented method the tracking error converges to a small value around zero while the neural network weights and system uncertainties remain bounded. Simulation on a robot manipulator model is presented to demonstrate the effectiveness of the proposed method.

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Journal of Renewable and Sustainable Energy, 2017

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Frontiers of Mechanical Engineering, 2017

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Frontiers of Mechanical Engineering, 2011

The aim of the paper is to analyze the nonlinear dynamics of robotic arms with elastic links and ... more The aim of the paper is to analyze the nonlinear dynamics of robotic arms with elastic links and joints. The main contribution of the paper is the comparative assessment of assumed modes and finite element methods as more convenient approaches for computing the nonlinear dynamic of robotic systems. Numerical simulations comprising both methods are carried out and results are discussed.

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Robotica, 2005

A computational algorithm is developed to find a dynamic motion trajectory of a mobile manipulato... more A computational algorithm is developed to find a dynamic motion trajectory of a mobile manipulator with flexible links and joints that will allow the robot to carry a maximum load between two specified end positions. A compact form of the linearized state space dynamic equations is organized as well as constraint equations. Then, the problem of finding a maximum load carrying capacity on flexible mobile manipulators is formulated as a trajectory optimization problem.

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International Journal of Advanced Robotic Systems, 2011

Finding optimal trajectory is critical in several applications of robot manipulators. This paper ... more Finding optimal trajectory is critical in several applications of robot manipulators. This paper is applied the open-loop optimal control approach for generating the optimal trajectory of the flexible mobile manipulators in point-to-point motion. This method is based on the Pontryagin's minimum principle that by providing a two-point boundary value problem is solved the problem. This problem is known to be complex in particular when combined motion of the base and manipulator, nonholonomic constraint of the base and highly non-linear and complicated dynamic equations as a result of flexible nature of links are taken into account. The study emphasizes on modeling of the complete optimal control problem by remaining all nonlinear state and costate variables as well as control constraints. In this method, designer can compromise between different objectives by considering the proper penalty matrices and it yields to choose the proper trajectory among the various paths. The effectiv...

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Applied Mathematical Modelling, 2012

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Acta Mechanica, 2013

ABSTRACT How to plan the optimal trajectory of nonholonomic mobile manipulators in dynamic enviro... more ABSTRACT How to plan the optimal trajectory of nonholonomic mobile manipulators in dynamic environments is a significant and challenging task, especially in the system with a moving target. This paper presents trajectory optimization of a nonholonomic mobile manipulator in dynamic environment pursuing a moving target. Full nonlinear dynamic equations of the system considering the nonholonomic constraints of wheels are presented. Then, dynamic motion planning of the system is formulated as an optimal control problem considering moving obstacle avoidance conditions. Accordingly, a new formulation of dynamic potential function was proposed based on the dynamic distance between colliding objects. In addition, an appropriate boundary value for a moving target was defined, and the resulted boundary value problem was solved to optimize the trajectory of the system. To solve the problem, an indirect solution of optimal control was applied which leads to transform the optimal control problem into a set of coupled differential equations. To demonstrate the efficiency and applicability of the method a number of simulations and experiments was performed for a spatial nonholonomic mobile manipulator.

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International Journal of Advanced Robotic Systems, 2012

In this work, a computational algorithm is developed for the smooth-jerk optimal path planning of... more In this work, a computational algorithm is developed for the smooth-jerk optimal path planning of tricycle wheeled mobile manipulators in an obstructed environment. Due to a centred orientable wheel, the tricycle mobile manipulator exhibits more steerability and manoeuvrability over traditional mobile manipulators, especially in the presence of environmental obstacles. This paper presents a general formulation based on the combination of the potential field method and optimal control theory in order to plan the smooth point-to-point path of the tricycle mobile manipulators. The nonholonomic constraints of the tricycle mobile base are taken into account in the dynamic formulation of the system and then the optimality conditions are derived considering jerk restrictions and obstacle avoidance. Furthermore, by means of the potential field method, a new formulation of a repulsive potential function is proposed for collision avoidance between any obstacle and each part of the mobile mani...

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2017 11th Asian Control Conference (ASCC), 2017

The safe operation of wind turbines is a vital criterion which should be considered in the contro... more The safe operation of wind turbines is a vital criterion which should be considered in the controller design to avoid rotor over speeding and hazardous operation. In this regard, the main focus of this paper is to keep the wind turbine operating within given limits by considering constrained control concepts using the barrier Lyapunov function. The nonlinear model of a benchmark wind turbine is considered and the wind speed variation is assumed to be unmeasurable disturbance and consequently, utilising the radial basis function neural network, an aerodynamic torque estimator is designed. The proposed controller is evaluated via numerical simulations and its performance is compared to a practical industrial wind turbine controller and a quadratic Lyapunov-based controller.

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Journal of Mechanisms and Robotics, 2021

This paper proposed a systematic framework to automatically design and fabricate optimized soft r... more This paper proposed a systematic framework to automatically design and fabricate optimized soft robotic fingers. The soft finger is composed of a soft silicone structure with inner air chambers and a harder outer layer, which are fabricated by molding process and 3D printing, respectively. The softer layer is utilized for actuation while the supportive hard structure is used to impose constraints. The framework applies a topology optimization approach based on RAMP method to obtain an optimal design of the outer layer of the soft fingers. Two basic motion primitives (bending and twisting) of the soft finger were explored. A multi-segmented soft bending finger and a soft twisting finger were designed and fabricated through the proposed framework. This work also explored the combination of bending and twisting primitives by developing a combined bending-twisting soft finger. The soft fingers were characterized by free and blocked movement tests. The experiments showed that the triplesegmented soft finger can achieve a maximum of 50.5 • no-load bending under the actuation pressure of 53 kPa. The blocked movement test on the multi-segmented soft actuating finger showed that this finger could generate up to a maximum of 0.63 N force under 57 kPa actuation pressure in 7 seconds of inflating time. The developed twisting soft finger was shown to achieve tip rotation of up to 219 degrees under 29 kPa actuation pressure. Finally, the potential capability of the bending-twisting soft fingers was verified through applications like screwing and object grasping.

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Research Square (Research Square), Dec 4, 2023

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Sciyo eBooks, Aug 12, 2010

ABSTRACT

Bookmarks Related papers MentionsView impact

IEEE Access

Bookmarks Related papers MentionsView impact

Bookmarks Related papers MentionsView impact

Bookmarks Related papers MentionsView impact

Journal of Mechanisms and Robotics, 2022

This paper proposed a systematic framework to automatically design and fabricate optimized soft r... more This paper proposed a systematic framework to automatically design and fabricate optimized soft robotic fingers. The soft finger is composed of a soft silicone structure with inner air chambers and a harder outer layer, which are fabricated by molding process and 3D printing, respectively. The softer layer is utilized for actuation while the supportive hard structure is used to impose constraints. The framework applies a topology optimization approach based on rational approximation of material properties (RAMP) method to obtain an optimal design of the outer layer of the soft fingers. Two basic motion primitives (bending and twisting) of the soft finger were explored. A multi-segmented soft bending finger and a soft twisting finger were designed and fabricated through the proposed framework. This work also explored the combination of bending and twisting primitives by developing a combined bending-twisting soft finger. The soft fingers were characterized by free and blocked movemen...

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This paper is concerned with the dynamic motion analysis and the planning of maximum payload path... more This paper is concerned with the dynamic motion analysis and the planning of maximum payload path of flexible manipulators. The finite element method was employed for dynamic modelling of the system and the motion of the model was considered as a combination of the rigid displacement and the elastic deformation of each link. Each manipulator link was treated as a finite number of elements and total displacement was derived by means of the shape functions of flexible elements. The problem of maximum payload trajectory planning was formulated as an optimal control problem. An indirect optimal control solution was employed. This method converts an optimality problem to a twopoint boundary value problem. The effect of the number of elements on the dynamic motion, optimal trajectory and maximum allowable dynamic payload of the system was studied. Finally, a number of simulations were performed to verify the applicability and capability of the method for the nonlinear dynamic modelling an...

Bookmarks Related papers MentionsView impact

Robot-assisted therapy can improve motor function in patients recovering from stroke. Assist-as-n... more Robot-assisted therapy can improve motor function in patients recovering from stroke. Assist-as-needed algorithms provide only minimal robotic assistance in the therapy, thus requiring significant effort from the impaired subject. This paper presents an adaptive neural assist-as-needed controller for rehabilitative robots. The controller combines the Lyapunov direct method with the computed torque control and neural networks. Robot assistance is limited to only as needed by adding the force reducing term into the adaptive control law. This paper shows that by the presented method the tracking error converges to a small value around zero while the neural network weights and system uncertainties remain bounded. Simulation on a robot manipulator model is presented to demonstrate the effectiveness of the proposed method.

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Journal of Renewable and Sustainable Energy, 2017

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Frontiers of Mechanical Engineering, 2017

Bookmarks Related papers MentionsView impact

Bookmarks Related papers MentionsView impact

Bookmarks Related papers MentionsView impact

Frontiers of Mechanical Engineering, 2011

The aim of the paper is to analyze the nonlinear dynamics of robotic arms with elastic links and ... more The aim of the paper is to analyze the nonlinear dynamics of robotic arms with elastic links and joints. The main contribution of the paper is the comparative assessment of assumed modes and finite element methods as more convenient approaches for computing the nonlinear dynamic of robotic systems. Numerical simulations comprising both methods are carried out and results are discussed.

Bookmarks Related papers MentionsView impact

Robotica, 2005

A computational algorithm is developed to find a dynamic motion trajectory of a mobile manipulato... more A computational algorithm is developed to find a dynamic motion trajectory of a mobile manipulator with flexible links and joints that will allow the robot to carry a maximum load between two specified end positions. A compact form of the linearized state space dynamic equations is organized as well as constraint equations. Then, the problem of finding a maximum load carrying capacity on flexible mobile manipulators is formulated as a trajectory optimization problem.

Bookmarks Related papers MentionsView impact

International Journal of Advanced Robotic Systems, 2011

Finding optimal trajectory is critical in several applications of robot manipulators. This paper ... more Finding optimal trajectory is critical in several applications of robot manipulators. This paper is applied the open-loop optimal control approach for generating the optimal trajectory of the flexible mobile manipulators in point-to-point motion. This method is based on the Pontryagin's minimum principle that by providing a two-point boundary value problem is solved the problem. This problem is known to be complex in particular when combined motion of the base and manipulator, nonholonomic constraint of the base and highly non-linear and complicated dynamic equations as a result of flexible nature of links are taken into account. The study emphasizes on modeling of the complete optimal control problem by remaining all nonlinear state and costate variables as well as control constraints. In this method, designer can compromise between different objectives by considering the proper penalty matrices and it yields to choose the proper trajectory among the various paths. The effectiv...

Bookmarks Related papers MentionsView impact

Applied Mathematical Modelling, 2012

Bookmarks Related papers MentionsView impact

Acta Mechanica, 2013

ABSTRACT How to plan the optimal trajectory of nonholonomic mobile manipulators in dynamic enviro... more ABSTRACT How to plan the optimal trajectory of nonholonomic mobile manipulators in dynamic environments is a significant and challenging task, especially in the system with a moving target. This paper presents trajectory optimization of a nonholonomic mobile manipulator in dynamic environment pursuing a moving target. Full nonlinear dynamic equations of the system considering the nonholonomic constraints of wheels are presented. Then, dynamic motion planning of the system is formulated as an optimal control problem considering moving obstacle avoidance conditions. Accordingly, a new formulation of dynamic potential function was proposed based on the dynamic distance between colliding objects. In addition, an appropriate boundary value for a moving target was defined, and the resulted boundary value problem was solved to optimize the trajectory of the system. To solve the problem, an indirect solution of optimal control was applied which leads to transform the optimal control problem into a set of coupled differential equations. To demonstrate the efficiency and applicability of the method a number of simulations and experiments was performed for a spatial nonholonomic mobile manipulator.

Bookmarks Related papers MentionsView impact

International Journal of Advanced Robotic Systems, 2012

In this work, a computational algorithm is developed for the smooth-jerk optimal path planning of... more In this work, a computational algorithm is developed for the smooth-jerk optimal path planning of tricycle wheeled mobile manipulators in an obstructed environment. Due to a centred orientable wheel, the tricycle mobile manipulator exhibits more steerability and manoeuvrability over traditional mobile manipulators, especially in the presence of environmental obstacles. This paper presents a general formulation based on the combination of the potential field method and optimal control theory in order to plan the smooth point-to-point path of the tricycle mobile manipulators. The nonholonomic constraints of the tricycle mobile base are taken into account in the dynamic formulation of the system and then the optimality conditions are derived considering jerk restrictions and obstacle avoidance. Furthermore, by means of the potential field method, a new formulation of a repulsive potential function is proposed for collision avoidance between any obstacle and each part of the mobile mani...

Bookmarks Related papers MentionsView impact

2017 11th Asian Control Conference (ASCC), 2017

The safe operation of wind turbines is a vital criterion which should be considered in the contro... more The safe operation of wind turbines is a vital criterion which should be considered in the controller design to avoid rotor over speeding and hazardous operation. In this regard, the main focus of this paper is to keep the wind turbine operating within given limits by considering constrained control concepts using the barrier Lyapunov function. The nonlinear model of a benchmark wind turbine is considered and the wind speed variation is assumed to be unmeasurable disturbance and consequently, utilising the radial basis function neural network, an aerodynamic torque estimator is designed. The proposed controller is evaluated via numerical simulations and its performance is compared to a practical industrial wind turbine controller and a quadratic Lyapunov-based controller.

Bookmarks Related papers MentionsView impact

Journal of Mechanisms and Robotics, 2021

This paper proposed a systematic framework to automatically design and fabricate optimized soft r... more This paper proposed a systematic framework to automatically design and fabricate optimized soft robotic fingers. The soft finger is composed of a soft silicone structure with inner air chambers and a harder outer layer, which are fabricated by molding process and 3D printing, respectively. The softer layer is utilized for actuation while the supportive hard structure is used to impose constraints. The framework applies a topology optimization approach based on RAMP method to obtain an optimal design of the outer layer of the soft fingers. Two basic motion primitives (bending and twisting) of the soft finger were explored. A multi-segmented soft bending finger and a soft twisting finger were designed and fabricated through the proposed framework. This work also explored the combination of bending and twisting primitives by developing a combined bending-twisting soft finger. The soft fingers were characterized by free and blocked movement tests. The experiments showed that the triplesegmented soft finger can achieve a maximum of 50.5 • no-load bending under the actuation pressure of 53 kPa. The blocked movement test on the multi-segmented soft actuating finger showed that this finger could generate up to a maximum of 0.63 N force under 57 kPa actuation pressure in 7 seconds of inflating time. The developed twisting soft finger was shown to achieve tip rotation of up to 219 degrees under 29 kPa actuation pressure. Finally, the potential capability of the bending-twisting soft fingers was verified through applications like screwing and object grasping.

Bookmarks Related papers MentionsView impact

Robot-assisted therapy can improve motor function in patients recovering from stroke. Assist-as-n... more Robot-assisted therapy can improve motor function in patients recovering from stroke. Assist-as-needed algorithms provide only minimal robotic assistance in the therapy, thus requiring significant effort from the impaired subject. This paper presents an adaptive neural assist-as-needed controller for rehabilitative robots. The controller combines the Lyapunov direct method with the computed torque control and neural networks. Robot assistance is limited to only as needed by adding the force reducing term into the adaptive control law. This paper shows that by the presented method the tracking error converges to a small value around zero while the neural network weights and system uncertainties remain bounded. Simulation on a robot manipulator model is presented to demonstrate the effectiveness of the proposed method.

Bookmarks Related papers MentionsView impact