Integration of Smart Actuators in the Structure of Robots for High-Speed and Precision Object Manipulation

2001 ◽  
Author(s):  
Jahangir S. Rastegar ◽  
Lifang Yuan
Keyword(s):  
High Speed ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
High Harmonic ◽  
Object Manipulation ◽  
Smart Actuators ◽  
Computer Controlled ◽  
Harmonic Components ◽  
Joint Motions ◽  
And Control

Abstract A systematic method is presented for optimal integration of smart actuators into the structure of robot manipulators for the purpose of enabling them to perform smooth object manipulation with smooth actuated joint motions. Here, the motions are considered to be smooth if they do not contain high harmonic components. For optimal positioning of smart actuators in the structure of robot manipulators, a method is developed based on the evaluation of the transmissibility of displacement (velocity and/or force) from the smart actuators to the robot manipulator joint motions and the end-effector displacements (velocity and/or force). A method is then presented for synthesizing actuated joint and object motions to achieve trajectories that do not contain high harmonic components. By minimizing the high harmonic components of the required joint and object motions with properly sized and placed smart actuators, such computer-controlled machines can operate at relatively higher speeds and achieve greater tracking precision with minimal vibration and control problems. A number of numerical examples are provided.

Optimal Smart Actuator Integration to Reduce Vibration in High Speed Mechanical Systems

2001 ◽  
Author(s):  
J. Rastegar ◽  
L. Yuan ◽  
L. Hua
Keyword(s):  
High Speed ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
High Harmonic ◽  
Smart Actuators ◽  
Computer Controlled ◽  
Harmonic Components ◽  
Smart Actuator ◽  
Joint Motions ◽  
And Control

Abstract A systematic method is presented for optimal integration of smart actuators into the structure of robot manipulators for the purpose of enabling them to perform smooth object manipulation with smooth actuated joint motions. Here, the motions are considered to be smooth if they do not contain high harmonic components. For optimal positioning of smart actuators in the structure of robot manipulators, a method is developed based on the evaluation of the transmissibility of displacement (velocity and/or force) from the smart actuators to the robot manipulator joint motions and the end-effector displacements (velocity and/or force). A method is then presented for synthesizing actuated joint and object motions to achieve trajectories that do not contain high harmonic components. By minimizing the high harmonic components of the required joint and object motions with properly sized and placed smart actuators, such computer-controlled machines can operate at relatively higher speeds and achieve greater tracking precision with minimal vibration and control problems. A number of numerical examples are provided.

Optimal Integration of Smart Actuators in the Structure of Serial and Parallel Robot Manipulators to Enhance Speed and Tracking Precision

2003 ◽  
Author(s):  
J. Rastegar ◽  
L. Yuan ◽  
J. Zhang
Keyword(s):  
Robot Manipulator ◽  
Robot Manipulators ◽  
High Harmonic ◽  
Harmonic Component ◽  
Optimal Placement ◽  
Operating Speed ◽  
End Effector ◽  
High Harmonics ◽  
Smart Actuators ◽  
Joint Motions

A method to determine optimal placement of smart (active) materials based actuators in the structure of robot manipulators for the purpose of achieving higher operating speed and tracking precision is developed. The method is based on the evaluation of the transmissibility of the displacement from the integrated smart actuators to the robot manipulator joint and end-effector displacements. By studying the characteristics of the Jacobian of the mapping function between the two displacements for a given position of the robot manipulator, the optimal positioning of the smart actuators that provides maximum effectiveness in eliminating high harmonics of the joint motion or the end-effector motion is determined. In robots with serial and parallel kinematics chains containing non-prismatic joints, due to their associated kinematics nonlinearity, if the joint motions were synthesized with low harmonic trajectories, the end-effector trajectory would contain high harmonics of the joint motions. Alternatively, if the end-effector motion were synthesized with low harmonic motions, due to the inverse kinematics nonlinearity, the actuated joint trajectories would contain a significant high harmonic component. As the result, the operating speed and tracking precision are degraded. By integrating smart materials based actuators in the structure of robot manipulators to provide small amplitude and higher frequency motions, the high harmonic component of the actuated joint and/or the end-effector motions are eliminated. As the result, higher operating speed and tracking precision can be achieved.

Trajectory Synthesis and Redundancy Resolution for High Speed Point to Point Motions of Redundant Robot Manipulators

1997 ◽  
Author(s):  
W. Kim ◽  
J. Rastegar
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
Dynamic Performance ◽  
High Harmonic ◽  
Harmonic Excitation ◽  
Redundancy Resolution ◽  
Tracking Accuracy ◽  
Point To Point

Abstract Trajectory synthesis for robot manipulators with redundant kinematic degrees-of-freedom has been studied by numerous investigators. Redundant manipulators are of interest since the redundant degrees-of-freedom can be used to improve the local and global kinematic and dynamic performance of a system. As a robot manipulator is forced to track a given trajectory, the required actuating torques (forces) may excite the natural modes of vibration of the system. Noting that manipulators with revolute joints have nonlinear dynamics, high harmonic excitation torques are generally generated even though such harmonics have been eliminated from the synthesized trajectories and filtered from the drive inputs. In this paper, a redundancy resolution method is developed based on the Trajectory Pattern Method (TPM) to synthesize trajectories such that the actuating torques required to realize them do not contain higher harmonic components with significant amplitudes. With such trajectories, a robot manipulator can operate at higher speeds and achieve higher tracking accuracy with suppressed residual vibration. As an example, optimal trajectories are synthesized for point to point motions of a plane 3R manipulator.

Micro/Macro or Link-Integrated Micro-actuator Manipulation—A Kinematics and Dynamics Perspective

2006 ◽  
Vol 129 (10) ◽  
pp. 1086-1093 ◽  
Author(s):  
J. Zhang ◽  
J. Rastegar
Keyword(s):  
Dynamic Response ◽  
Closed Loop ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
High Harmonic ◽  
Kinematics And Dynamics ◽  
Control Problems ◽  
End Effector ◽  
Micro Actuators ◽  
And Control

Smart (active) materials based actuators, hereinafter called micro-actuators, have been shown to be well suited for the elimination of high harmonics in joint and/or end-effector motions of robot manipulators and in the reduction of actuator dynamic response requirements. Low harmonic joint and end-effector motions, as well as low actuator dynamic response requirements, are essential for a robot manipulator to achieve high operating speed and precision with minimal vibration and control problems. Micro-actuators may be positioned at the end-effector to obtain a micro- and macro-robot manipulation configuration. Alternatively, micro-actuators may be integrated into the structure of the links to vary their kinematics parameters, such as their lengths during the motion. In this paper, the kinematics and dynamics consequences of each of the aforementioned alternative are studied for manipulators with serial and closed-loop chains. It is shown that for robot manipulators constructed with closed-loop chains, the high harmonic components of all joint motions can be eliminated only when micro-actuators are integrated into the structure of the closed-loop chain links. The latter configuration is also shown to have dynamics advantage over micro- and macro-manipulator configuration by reducing the potential vibration and control problems at high operating speeds. The conclusions reached in this study also apply to closed-loop chains of parallel and cooperating robot manipulators.

Smart Actuator Positioning and Displacement Transmissibility in Serial and Parallel Robot Manipulators for Performance Enhancement

2004 ◽  
Vol 127 (4) ◽  
pp. 589-595 ◽  
Author(s):  
J. Rastegar ◽  
L. Yuan ◽  
J. Zhang
Keyword(s):  
Smart Materials ◽  
Performance Enhancement ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
High Harmonic ◽  
Harmonic Component ◽  
Operating Speed ◽  
End Effector ◽  
High Harmonics ◽  
Joint Motions

A method is presented for the evaluation of the transmissibility of displacement from smart (active) actuators integrated in the structure of robot manipulators to the manipulator joint and end-effector displacements. The method is based on studying the characteristics of the Jacobian of the mapping function between the two displacements for a given position of the robot manipulator. The developed method provides a tool for the determination of the positioning of smart actuators to provide maximum effectiveness in eliminating high harmonics of the joint or the end-effector motion. In robots with serial and parallel kinematics chains containing nonprismatic joints, due to the associated kinematics nonlinearity, if the joint motions were synthesized with low harmonic trajectories, the end-effector trajectory would still contain high harmonics of the joint motions. Alternatively, if the end-effector motion were synthesized with low harmonic components, due to the inverse kinematics nonlinearity, the actuated joint trajectories would contain a significant high harmonic component. As a result, the operating speed and tracking precision are degraded. By integrating smart materials based actuators in the structure of robot manipulators to provide small amplitude and high frequency motions, the high harmonic component of the actuated joint and/or the end-effector motions can be significantly reduced, thereby making it possible to achieve higher operating speed and tracking precision.

Optimal Integration of Smart Actuators in Parallel and Cooperating Robots to Enhance Operating Speed and Accuracy

2001 ◽  
Author(s):  
L. Yuan ◽  
J. Rastegar
Keyword(s):  
Robot Manipulators ◽  
High Harmonic ◽  
Control Problems ◽  
Operating Speed ◽  
Parallel Kinematics ◽  
Optimal Integration ◽  
Highly Nonlinear ◽  
Cooperating Robots ◽  
Harmonic Components ◽  
Joint Motions

Abstract Robot manipulators with parallel kinematics chains and two or more robots manipulating an object form closed kinematics chains. When revolute joints are used in the construction of such robotic manipulation systems, the presence of closed chains and their associated kinematics nonlinearity demands high harmonic motions in at least a number of the actuated joints. This is the case even if all the links are relatively rigid and attempt is made to synthesize the joint motions with minimal harmonic content. The presence of high harmonic components in the actuated joint motions is undesirable since as the operating speed is increased, their frequencies would rapidly increase and move beyond the dynamic response limitations of the actuating drives, thereby causing vibration and control problems. The performance of the system in terms of cycle time, tracking precision and the like would therefore suffer. This is particularly the case since the dynamics of such systems is also highly nonlinear and require higher harmonic components in the actuating torques (forces). In this paper, a systematic method is presented for optimal integration of smart (active) materials based actuators into the structure of cooperating robots and robot manipulators with parallel kinematics chain for the purpose of eliminating the high harmonic components of their actuated joint motions. As the result, the potential excitation of the natural modes of vibration of such systems and their related control problems can be greatly reduced. The resulting robotic systems should therefore be capable of operating at higher speeds with increased precision.

Reduction of Induced Vibration Using Motion-Doubling Linkage Mechanisms

2006 ◽  
Author(s):  
J. Rastegar ◽  
J. Zhang
Keyword(s):  
High Speed ◽  
High Harmonic ◽  
Full Rotation ◽  
Rocking Motion ◽  
Points Of View ◽  
Harmonic Components ◽  
Input Motion ◽  
And Control ◽  
Special Case ◽  
Input Torque

In recent studies, the authors presented a special class of planar and spatial linkage mechanisms in which for a continuous full rotation or continuous rocking motion of the input link, the output link undergoes two continuous rocking motions. Such linkage mechanisms were referred to as the “motion-doubling” linkage mechanisms. It was also shown that in a special case of such mechanisms, the fundamental frequency of the input motion is doubled. This class of mechanisms generally has dynamics advantage over regular mechanisms designed to achieve similar gross output motions. In the present study, it is shown that in general and for the same gross output motion, motion-doubling mechanisms require lower input torques, and that the high harmonics of the input torque have smaller amplitudes. The high harmonic components present in the input torque are the main source of vibration and control problems in the system or device that the mechanism operates and its own structure. It is therefore concluded that when vibration and motion precision is of concern, such as in high-speed and precision machinery, motion-doubling mechanisms are generally more suitable from the potential vibration excitation and control points of view and actuating torque requirements.

Optimal Motion Patterns for Golf Swings

1998 ◽  
Author(s):  
L. Yuan ◽  
J. Rastegar ◽  
F. Pollo
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Response ◽  
High Speed ◽  
Robot Manipulator ◽  
High Harmonic ◽  
Maximum Output ◽  
Robot Arm ◽  
Motion Patterns ◽  
Joint Torques ◽  
Harmonic Content

Abstract Due to the dynamic response and maximum output force (torque) limitations of their actuating motors, computer controlled machines such as robot manipulators can only have a limited performance in terms of the time to complete a specified motion and other similar measures of operating speed. For example, a robot manipulator arm with limited joint motion can only reach a maximum end-effector speed due to the aforementioned limitations of its actuating torque. The dynamic response limitations of the actuators dictate that for high speed motions, the robot arm should be required to follow trajectories for which the required actuating torques do not contain harmonics with frequencies beyond the “bandwidth” of its actuators. For systems with nonlinear dynamics such as robot arms with revolute joints operating at high speeds, the higher harmonics of the actuating torques are the harmonics of the joint trajectories that are generated due to the nonlinear dynamics of the system. During sport activities, the muscle forces and the resulting limb motions can also be expected to be subject to similar dynamic response limitations. The present study examines such a hypothesis. The measured motion at the shoulder and the wrist of an experienced golfer during downswing is measured and together with the required muscle generated actuating torques are analyzed for their harmonic content. Similar analysis is also performed for published motion data for expert golfers. The results confirm the hypothesis that optimal golf swing motions consist almost entirely of low harmonic patterns that are synthesized to require joint torques with negligible high harmonic content.

scholarly journals A Novel Computer-Controlled Maskless Fabrication Process for Pneumatic Soft Actuators

Actuators ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 136
Author(s):  
Luke J. Tinsley ◽  
Russell A. Harris
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Selective Treatment ◽  
Pneumatic Chamber ◽  
Design Variation ◽  
Chemical Behaviour ◽  
Computer Controlled ◽  
Manufacturing Techniques ◽  
Soft Actuators ◽  
And Control

Template-based and additive manufacturing techniques have demonstrated some fabrication routes for creating pneumatic soft actuators. However, as the complexity and capability of the actuators continue to develop, the limitations of these approaches are becoming evident. These include difficulties for design variations, process speed and resolution, material compatibility and scalability, which hinder and restrict both the possible capabilities of the technology and its transition from research to industry. This body of work presents a computer-controlled, maskless manufacturing process with a different approach to allow for high-speed, low-cost and flexible creation of pneumatic soft actuation networks comprising multi-material construction. This was investigated through a bespoke fabrication platform that provides computer-controlled localised plasma treatment to selectively modify the chemical behaviour on the surface of silicone and polyethylene terephthalate (PET) bodies. The altered surface chemistry facilitated selective bond formation between the treated parts of the surface and, consequently, greater design variation and control over the pneumatic chambers that were formed. Selective treatment patterns allowed nonlinear pneumatic chamber designs to be created, and the strength of bonded silicone structures was shown to facilitate large deformations in the actuators. Furthermore, the different interactions between the plasma and silicone were leveraged to achieve feature sizes of <1 mm and treatment speeds of 20 mm2 per second of exposure. Two multi-material pneumatic soft actuators were then fabricated to demonstrate the potential of the platform as an automated manufacturing route for soft actuators.

New P-type RMPC Scheme for Redundant Robot Manipulators in Noisy Environment

Robotica ◽  
2019 ◽  
Vol 38 (5) ◽  
pp. 775-786 ◽  
Author(s):  
Zexin Li ◽  
Feng Xu ◽  
Dongsheng Guo ◽  
Pingjiang Wang ◽  
Bo Yuan
Keyword(s):  
Truncation Error ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
Rounding Error ◽  
Noisy Environment ◽  
Repetitive Motion ◽  
Redundant Robot ◽  
Planning And Control ◽  
P Type ◽  
And Control

SUMMARYRepetitive motion planning and control (RMPC) is a significant issue in the research of redundant robot manipulators. Moreover, noise from rounding error, truncation error, and robot uncertainty is an important factor that greatly affects RMPC schemes. In this study, the RMPC of redundant robot manipulators in a noisy environment is investigated. By incorporating the proportional and integral information of the desired path, a new RMPC scheme with pseudoinverse-type (P-type) formulation is proposed. Such a P-type RMPC scheme possesses the suppression of constant and bounded time-varying noises. Comparative simulation results based on a five-link robot manipulator and a PUMA560 robot manipulator are presented to further validate the effectiveness and superiority of the proposed P-type RMPC scheme over the previous one.

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