scholarly journals Inverse Kinematics with a Geometrical Approximation for Multi-Segment Flexible Curvilinear Robots

Robotics ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 48 ◽  
Author(s):  
Sehun Kim ◽  
Wenjun Xu ◽  
Hongliang Ren
Keyword(s):  
Inverse Kinematics ◽  
Fitness Function ◽  
Flexible Manipulator ◽  
Direct Drive ◽  
Real Time Control ◽  
Physical Force ◽  
Continuum Robots ◽  
Time Control ◽  
Inverse Results ◽  
Starting Point

Despite research related to flexible or continuum curvilinear robots, there lacks a common simulation tool for continuum robots, which are unlike rigid robots. Thus, in this paper, a robotics toolbox is utilized to model a wire-driven flexible manipulator as one of the continuum robots. Constant curvature property can enable the robotics toolbox to represent the flexible manipulator and validate its kinematics. Moreover, because the closed-form inverse kinematics methods developed previously for real-time control conceded limitations in modeling some continuum robots, we hereby develop an inverse kinematics method for the wire-driven flexible manipulator which can provide fast and reliable inverse results. Experimental results showed that geometrical information offered a stable starting point for the proposed inverse kinematics algorithm. Moreover, the first and second derivatives of a fitness function further contributed to a fast-converging solution within a few microseconds. Lastly, for the potential feasibility of an active compliance controller without physical force/torque sensors, a reaction torque observer was investigated for a flexible manipulator with direct drive mechanisms.

The Algorithm of Redundant Robotic Kinematics Based on Exponential Product

2011 ◽  
Vol 58-60 ◽  
pp. 1902-1907 ◽  
Author(s):  
Xin Fen Ge ◽  
Jing Tao Jin
Keyword(s):  
Real Time ◽  
Inverse Kinematics ◽  
Screw Theory ◽  
Product Formula ◽  
Real Time Control ◽  
Time Control ◽  
Direct Kinematics ◽  
Product Formulas

The intrinsically redundant series manipulator’s kinematics were studied by the exponential product formula of screw theory, the direct kinematics problem and Inverse kinematics problems were analyzed, and the intrinsically redundant series manipulator’s kinematics solution that based on exponential product formulas were proposed; the intrinsically redundant series manipulator’s kinematics is decomposed into several simple sub-problems, then analyzed sub-problem, and set an example to validate the correctness of the proposed method. Finally, comparing the exponential product formula and the D-H parameters, draw that they are essentially the same in solving the manipulator’s kinematics, so as to the algorithm of the manipulator’s kinematics based on exponential product formulas are correct, and the manipulator’s kinematics process based on exponential product formula is more simple and easier to real-time control of industrial.

Damping Mechanisms in Cable-Harnessed Structures for Space Applications: Analytical Modeling

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Pranav Agrawal ◽  
Armaghan Salehian
Keyword(s):  
Structural Parameters ◽  
Analytical Models ◽  
Space Structures ◽  
Real Time Control ◽  
Space Applications ◽  
Time Control ◽  
Starting Point ◽  
Recent Developments ◽  
Damping Effects ◽  
Distributed Transfer Function

Abstract Recent developments in the aerospace industry have driven focus toward accurately modeling the effects of the cables and electronic cords on space structures. In the past, researchers have modeled the mass and stiffness effects of these cables but primarily overlooked their damping effects through careful analytical model developments. The objective of the current work is to present analytical models for cable-harnessed structures that also include the damping effects in their vibration response. Obtaining simple, low-order and high-fidelity models are highly advantageous in designing robust vibration real-time control algorithms for structures. Additionally, the analytical models are useful tools in providing insight into and better understanding of the dynamics of space structures as they are often difficult to be tested prior to launch due to their large size and at best only a few components may be tested. Motivated by the space applications, this work considers beam structures wrapped with cables which are modeled using beam and string theory assumptions. Two different damping models namely Kelvin–Voigt and hysteretic damping are considered. The homogenization approach is used as a starting point for structures of periodic wrapping patterns. Using the variational principle, the governing partial differential equation for the transverse coordinate of vibrations is found for three cable patterns and the results are compared to those from the distributed transfer function method (DTFM). Finally, the effects of several structural parameters are studied on the overall system damping.

Windows-based real-time control of direct-drive mechanisms: platform description and experiments

Mechatronics ◽  
2004 ◽  
Vol 14 (9) ◽  
pp. 1021-1036 ◽  
Author(s):  
Ricardo Campa ◽  
Rafael Kelly ◽  
Victor Santibañez
Keyword(s):  
Real Time ◽  
Direct Drive ◽  
Real Time Control ◽  
Time Control

Redundancy Parameterization for Flexible Motion Control

2010 ◽  
Author(s):  
B. Moore ◽  
E. Oztop
Keyword(s):  
Finite Number ◽  
Inverse Kinematics ◽  
Infinitely Many Solutions ◽  
Redundant Manipulators ◽  
Real Time Control ◽  
End Effector ◽  
Human Control ◽  
Time Control ◽  
Swivel Angle ◽  
Self Motion

Our overall research interest is in synthesizing human like reaching and grasping using anthropomorphic robot hand-arm systems, as well as understanding the principles underlying human control of these actions. When one needs to define the control and task requirements in the Cartesian space, the problem of inverse kinematics needs to be solved. For non-redundant manipulators, a desired end-effector position and orientation can be achieved by a finite number of solutions. For redundant manipulators however, there are in general infinitely many solutions where the cardinality of the solution set must be made finite by imposing certain constraints. In this paper, we consider the Mitsubishi PA10 manipulator which is similar to the human arm, in the sense that both wrist and shoulder joints can be considered to emulate a 3DOF ball joint. We explicitly derive the analytic solution for the inverse kinematics using quaternions. Then, we derive a parameterization in terms of a pure quaternion called the swivel quaternion. The swivel quaternion is similar to the elbow swivel angle used in most approaches, but avoid the computation of inverse trigonometric functions. This parameterization of the self-motion manifold is continuous with any end-effector motion. Given the pose of the end-effector and the swivel quaternion (or swivel angle), the algorithm derives all solution of the inverse kinematics (finite number). We then show how the parameterization of the elbow self-motion can be used for the real-time control of the PA10 manipulator in the presence of obstacles.

A New Approach to Model Constant Curvature Continuum Robot Dynamics

2019 ◽  
Author(s):  
Yujiong Liu ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Constant Curvature ◽  
Inverse Dynamics ◽  
Virtual Work ◽  
Robot Dynamics ◽  
Real Time Control ◽  
Continuum Robots ◽  
New Approach ◽  
Time Control ◽  
Proposed Model ◽  
Vector Representations

Abstract Inspired by nature, continuum robots show their potential in human-centered environments due to the compliant-to-obstacle features and dexterous mobility. However, there are few such robots successfully implemented outside the laboratory so far. One reason is believed to be due to the real time control challenge for soft robots, which require a highly efficient, highly accurate dynamic model. This paper presents a new systematic methodology to formulate the dynamics of constant curvature continuum robots. The new approach builds on several new techniques: 1) using the virtual work principle to formulate the equation of motion, 2) using specifically selected kinematic representations to separate integral variables from the non-integral variables, and 3) using vector representations to put the integral in a compact form. By doing so, the hard-to-solve integrals are evaluated analytically in advance and the accurate inverse dynamics are established accordingly. Numerical simulations are conducted to evaluate the performances of the newly proposed model.

Synergetic Design of Shell Structure and Space Art Based on Architectural Parametric Design

2014 ◽  
Vol 912-914 ◽  
pp. 1784-1787
Author(s):  
Chao Hao Su
Keyword(s):  
Real Time ◽  
Shell Structure ◽  
Parametric Design ◽  
Digital Design ◽  
Real Time Control ◽  
Natural Lighting ◽  
Time Control ◽  
Starting Point ◽  
Modern Context ◽  
Space Art

The design tries to discuss and explode the synergetic methods of shell structure and buildings shape and space, considering the architectural regionalism and publicity as an iportant starting point. Based on the mechanics of shell structure, paramtric design methods are used to realize natural lighting and dramatic scene through openning holes on the hyperbolic haraboloid shell, under the dynamic and real-time control of structural computing software. Through digital design technology, expressive morphology of shell structure is re-created in modern context, reaching the aim of economy, efficiency and beauty in structural art.

scholarly journals A Methodology for the Design of RTC Strategies for Combined Sewer Networks

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1675 ◽  
Author(s):  
Stefan Kroll ◽  
Marjoleine Weemaes ◽  
Jan Van Impe ◽  
Patrick Willems
Keyword(s):  
Control Strategies ◽  
Real Life ◽  
Control Algorithms ◽  
Real Time Control ◽  
Practical Applications ◽  
Time Control ◽  
Drainage Networks ◽  
Starting Point ◽  
Combined Sewer ◽  
Large Case

While real-time control (RTC) is considered an established means of performance improvement for existing urban drainage networks, practical applications are frequently only documented for large case studies, and many operators are still reluctant to adopt RTC into their own systems. The purpose of the presented study is to highlight the potential of RTC also for smaller networks by the example of five representative catchments in Flanders, Belgium, and to demonstrate a novel methodology for the automated design of control strategies. This method analyses a given sewer network for the identification of suitable existing and new control locations. The gathered information is used in a second step for the design of control algorithms according to generic control concepts documented in the literature, such as e.g., “Equal Filling Degree”. The resulting RTC strategy uses sensible default parameters, and can form a starting point for further refinement through optimization or manual tuning. With a modelled total combined sewer overflow volume reduction of 20% to 50%, the created strategies showed generally good performance for the tested catchments. The method proved to be applicable for all tested networks. Its use for the real-life implementation of RTC is currently under way for 10 other Flemish cases.

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