scholarly journals Design of a Five-Degrees of Freedom Statically Balanced Mechanism with Multi-Directional Functionality

Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Terence Essomba
Keyword(s):  
Potential Energy ◽  
Degrees Of Freedom ◽  
Surgical Instruments ◽  
Gravitational Potential Energy ◽  
Cad Model ◽  
Linear Motion ◽  
Mechanical Parameters ◽  
End Effector ◽  
Elastic Potential Energy ◽  
Selection Of

A statically balanced mechanism is designed as a potential solution for the positioning of surgical instruments. Its kinematics with five degrees of freedom that decouples linear and angular motions is proposed for that objective. The linear motion of its end effector is provided by a classical parallelogram linkage. To enhance its adaptability, a mechanical system allows re-orienting the position mechanism in three different working modes (horizontal, upward and downward) while preserving its static balance. Based on the mechanical concept, a uniformized static balancing condition that considers all working modes is given. The orientation of the end effector is provided by a spherical decoupled mechanism. It generates a remote center of motion which is highly representative of kinematics in surgery requirements. Based on the mechanism kinematics, the evolution of its gravitational potential energy is studied. Two different mechanical concepts are then proposed to generate a compensating elastic potential energy. A CAD model of the entire mechanism has allowed the estimation of all mechanical parameters for the selection of the appropriate tension springs and for carrying out validation simulations. A prototype of the statically balanced mechanism is fabricated and successfully tested.

Kinematics of a Fully-Decoupled Remote Center-of-Motion Parallel Manipulator for Minimally Invasive Surgery

2012 ◽  
Vol 6 (2) ◽  
Author(s):  
Chin-Hsing Kuo ◽  
Jian S. Dai
Keyword(s):  
Minimally Invasive Surgery ◽  
Minimally Invasive ◽  
Invasive Surgery ◽  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Surgical Instruments ◽  
End Effector ◽  
Minimally Invasive Surgical ◽  
Inverse Kinematics Problem

A crucial design challenge in minimally invasive surgical (MIS) robots is the provision of a fully decoupled four degrees-of-freedom (4-DOF) remote center-of-motion (RCM) for surgical instruments. In this paper, we present a new parallel manipulator that can generate a 4-DOF RCM over its end-effector and these four DOFs are fully decoupled, i.e., each of them can be independently controlled by one corresponding actuated joint. First, we revisit the remote center-of-motion for MIS robots and introduce a projective displacement representation for coping with this special kinematics. Next, we present the proposed new parallel manipulator structure and study its geometry and motion decouplebility. Accordingly, we solve the inverse kinematics problem by taking the advantage of motion decouplebility. Then, via the screw system approach, we carry out the Jacobian analysis for the manipulator, by which the singular configurations are identified. Finally, we analyze the reachable and collision-free workspaces of the proposed manipulator and conclude the feasibility of this manipulator for the application in minimally invasive surgery.

A Friction-Bearing Calorimeter Experiment Yielding Joule's Constant

1996 ◽  
Vol 24 (4) ◽  
pp. 235-242 ◽  
Author(s):  
R. S. Mullisen
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Laboratory Experiment ◽  
Heat Loss ◽  
Gravitational Potential ◽  
Data Reduction ◽  
Gravitational Potential Energy ◽  
Experimental Procedure ◽  
Friction Bearing ◽  
Elastic Potential Energy

A simple, friction-bearing calorimeter that yields Joule's constant is described in this paper. The apparatus is easily constructed at minimal expense and may be used as a laboratory experiment. Although the design is very simple, the experimental procedure and data reduction analysis account for gravitational potential energy, elastic potential energy, translational and rotational kinetic energy, and heat loss. The result is a Joule's constant value accurate within 3%.

Development of a Haptic Device with Wire-Driven Parallel Structure

2017 ◽  
Vol 11 (3) ◽  
pp. 385-395
Author(s):  
Carlo Ferraresi ◽  
◽  
Carlo De Benedictis ◽  
Francesco Pescarmona
Keyword(s):  
Degrees Of Freedom ◽  
Force Feedback ◽  
Parallel Structure ◽  
Control Logic ◽  
End Effector ◽  
Six Degrees Of Freedom ◽  
Force Closure ◽  
Force Reflection ◽  
Definition Of ◽  
Selection Of

This study focuses on the specific problems that may arise in the development of a parallel, cable-driven device designed for teleoperations systems utilizing force-reflection feedback. A redundant six degrees-of-freedom structure, actuated by nine wires, is described as a convenient layout for a haptic master for telemanipulation. A methodology for the kinematic and static analysis and the evaluation of the device workspace is described. The condition of force closure is used to find all available poses of the end-effector, thereby defining the workspace, whose characteristics are assessed by opportunely conceived indexes. Typical characteristics of cable and implementations thereof in the device are considered. Regarding the realization of the device, relevant attention is given to the definition of the control logic, which can be complex for parallel devices. The selection of the actuators, crucial in realizing force feedback, is discussed. In particular, pneumatic actuation is considered, verified as the most appropriate method for implementation and force control of the cylinders.

On the Perfect Gravity-Balance of a Spatial N-DOF Manipulator Based on the Localized Pseudo-Base

2009 ◽  
Author(s):  
Po-Yang Lin ◽  
Win-Bin Shieh ◽  
Dar-Zen Chen
Keyword(s):  
Exact Solution ◽  
Potential Energy ◽  
Gravitational Potential ◽  
Rotation Axis ◽  
Industrial Robot ◽  
Elastic Potential ◽  
Gravitational Potential Energy ◽  
Mass Center ◽  
Elastic Potential Energy ◽  
Six Dof

This paper offers an exact solution for the perfect gravity-balance of a class of spatial manipulators with no translational joints. The methodology used is based on the concept of conservation of the gravitational and elastic potential energy of the system. The overall gravitational potential energy of a serial-connected, n-link manipulator is identified to be contributed by n subsystems, where each subsystem is kinematically equivalent to one of the primary links of the manipulator, and possesses the accumulated mass of its post-connected links with a fixed mass center located on the subsystem. The gravitational potential energy of such a subsystem can be fully balanced by the elastic potential energy of the spring fitted between the link and its adjacent pseudo-base. Since the rotation axis of the pseudo-base is required to be in the direction of gravity, n serial-connected RSSR modules are constituted along the primary chain of the manipulator to provide a pseudo-base for each of the primary links. With one linear, zero-free-length spring fitted between each of the primary links of the manipulator and its associated pseudo-base, a static equilibrium of the considered mechanism in any configuration can be reached. A numerical example of the model of a six-DOF industrial robot has demonstrated the success of the proposed methodology.

Design of Perfectly Static-Balanced One-DOF Planar Linkage With Revolute Joint Only

2008 ◽  
Author(s):  
Po-Yang Lin ◽  
Win-Bin Shieh ◽  
Dar-Zen Chen
Keyword(s):  
Potential Energy ◽  
Gravitational Potential ◽  
Elastic Potential ◽  
Gravitational Potential Energy ◽  
Single Degree Of Freedom ◽  
Parallel Links ◽  
Parallel Motion ◽  
Systematic Methodology ◽  
Elastic Potential Energy ◽  
Spring Constants

A systematic methodology for the design of a statically balanced, single degree-of-freedom planar linkage is presented. This design methodology is based on the concept of conservation of potential energy, formulated by the use of complex number notations as link vectors of the linkage. By incorporating the loop closure equations, the gravitational potential energy of the system can be simplified as the function of the vectors of all ground-adjacent links. The balance of the gravitational potential energy of the system is then accomplished by the elastic potential energy of a zero free-length spring on each ground-adjacent link of the linkage. As a result, spring constants and installation configurations of the ground-attached springs are obtained. Since the variation of the gravitational potential energy of the linkage at all configurations can be fully compensated by that of the elastic potential energy of springs, this methodology provides an exact solution for the design of a general spring balancing mechanism without auxiliary parallel links. Illustrations of the methodology are successfully demonstrated by the spring balancing designs of a general Stephenson-III type six-bar linkage and a Watt-I type six-bar linkage with parallel motion.

Design of Perfectly Statically Balanced One-DOF Planar Linkages With Revolute Joints Only

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Po-Yang Lin ◽  
Win-Bin Shieh ◽  
Dar-Zen Chen
Keyword(s):  
Potential Energy ◽  
Gravitational Potential ◽  
Elastic Potential ◽  
Gravitational Potential Energy ◽  
Revolute Joints ◽  
Parallel Links ◽  
Parallel Motion ◽  
Elastic Potential Energy ◽  
Planar Linkages ◽  
Spring Constants

A systematic methodology for the design of a statically balanced, single degree-of-freedom planar linkage is presented. This design methodology is based on the concept of conservation of potential energy, formulated by the use of complex number notations as link vectors of the linkage. By incorporating the loop closure equations and the kinematic constraints, the gravitational potential energy of the system can be formulated as the function of the vectors of all ground-adjacent links. The balance of the gravitational potential energy of the system is then accomplished by the elastic potential energy of a zero free-length spring on each ground-adjacent link of the linkage. As a result, spring constants and installation configurations of the ground-attached springs are obtained. Since the variation in the gravitational potential energy of the linkage at all configurations can be fully compensated by that of the elastic potential energy of the ground-attached springs, this methodology provides an exact solution for the design of a general spring balancing mechanism without auxiliary parallel links. Illustrations of the methodology are successfully demonstrated by the spring balancing designs of a general Stephenson-III type six-bar linkage and a Watt-I type six-bar linkage with parallel motion.

scholarly journals A gravity balancing assistant arm design in 3-D for rehabilitation of stroke patients

2021 ◽  
Vol 336 ◽  
pp. 02016
Author(s):  
Jianbo Shu ◽  
Xuehua Tang ◽  
Fan Niu ◽  
Changchun Xia ◽  
Congcong Shi
Keyword(s):  
Potential Energy ◽  
Gravitational Potential ◽  
Energy Equation ◽  
Elastic Potential ◽  
Gravitational Potential Energy ◽  
Practical Application ◽  
Stroke Patients ◽  
Rigid Rods ◽  
Motion Process ◽  
Elastic Potential Energy

A gravity balancing assistant arm design in 3-D is a mechanical mechanism consisted of springs, rigid rods, joints and sliders, which can be modified to the geometry and inertia of the arm of stroke patients. This mechanism is designed without any controllers and motors, based solely on mechanical principles, to achieve a relative balance of gravitational potential energy and elastic potential energy, thereby reducing the burden on the arm of a stroke patient to facilitate rehabilitation. To achieve this function, first, the center of gravity of the patient’s arm will be positioned, and then the mounting position of the spring on the assistant arm will be determined. In this paper, the following objectives will be achieved: (i) the calculation of the gravitational potential energy and the elastic potential energy in the mechanism (ii) the simplification of the potential energy equation and the elimination of the coefficient of the items related to the angle. (iii) The comparison between 2-D and 3-D cases of the mechanism. (iv) The motion process of simulating the mechanism using MATLAB (v) Using MATLAB to create the energy plots (vi) Using SolidWorks to construct the prototype of the mechanism (vii) Describe the practical application and future extensions of this mechanism.

scholarly journals Two typical merging events of oceanic mesoscale anticyclonic eddies

2019 ◽  
Author(s):  
Zi-Fei Wang ◽  
Liang Sun ◽  
Qiu-Yang Li ◽  
Hao Cheng
Keyword(s):  
Potential Energy ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Center Of Mass ◽  
Gravitational Potential Energy ◽  
Initial State ◽  
Final State ◽  
Inverse Energy Cascade ◽  
Eddy Potential Energy ◽  
Anticyclonic Eddies

Abstract. The long-term theoretical energy paradox of whether the final state of two merging anticyclones contains more energy than the initial state is studied by observing two typical merging events of ocean mesoscale eddies. It is found that the total mass (volume), total circulation (area integration of vorticity) and total angular momentum (AM) are conserved if the orbital AM relative to the center of mass is taken into account as the eddies rotate around the center of mass before merging. For subsurface merging, the mass trapped by the Taylor–Proudman effect above the subsurface eddies should also be included. Both circulation conservation laws and orbital AM have been overlooked in previous theoretical studies. The total eddy kinetic energy slightly decreases after merging due to fusion. On the contrary, the total eddy potential energy (EPE) significantly increases after the merging. The increase of the EPE is mostly supported by the loss of gravitational potential energy (PE) via eddy sinking below the original level. This implies that the merging of eddies requires the background gravitational PE to convert to the EPE. In contrast, the vorticity and enstrophy consequently decrease after merging. Thus, the eddy merging effect behaves as a large-scale energy pump in an inverse energy cascade. It is noted that eddy conservation and conversion laws depend on laws of physical dynamics, even if additional degrees of freedom can be provided in a mathematical model.

Output force capacity polytope approach for actuator forces selection of three degrees of freedom excavating manipulator

2013 ◽  
Vol 228 (11) ◽  
pp. 2007-2017 ◽  
Author(s):  
Baochen Wei ◽  
Feng Gao
Keyword(s):  
Degrees Of Freedom ◽  
Gravity Effect ◽  
End Effector ◽  
Output Capacity ◽  
Output Force ◽  
Single Force ◽  
The Relationship ◽  
Three Degrees Of Freedom ◽  
Selection Of

Output force or velocity polytopes are usually used as an index of the manipulability of robot. This paper discusses the relationship between the actuator force and the variation of the output force capacity polytope and proposes the output force capacity polytope method for the selection of actuator forces of a three degrees of freedom excavating manipulator with the requirement that the output force on the end effector is a set of all possible forces rather than a single force. In this paper, the method to calculate capacity polytope is introduced with the consideration of gravity effect. With the concept that the required output force space should be within the output capacity polytope, the output force capacity polytope approach for selecting actuator forces is proposed.

scholarly journals Two typical merging events of oceanic mesoscale anticyclonic eddies

Ocean Science ◽  
2019 ◽  
Vol 15 (6) ◽  
pp. 1545-1559 ◽  
Author(s):  
Zi-Fei Wang ◽  
Liang Sun ◽  
Qiu-Yang Li ◽  
Hao Cheng
Keyword(s):  
Potential Energy ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Center Of Mass ◽  
Gravitational Potential Energy ◽  
Initial State ◽  
Final State ◽  
Inverse Energy Cascade ◽  
Eddy Potential Energy ◽  
Anticyclonic Eddies

Abstract. The long-term theoretical “energy paradox” of whether the final state of two merging anticyclones contains more energy than the initial state is studied by considering two typical merging events of ocean mesoscale eddies. The results demonstrate that the total mass (volume), total circulation (area integration of vorticity), and total angular momentum (AM) are conserved if the orbital AM relative to the center of mass is taken into account as the eddies rotate around the center of mass before merging. For subsurface merging, the mass trapped by the Taylor–Proudman effect above the subsurface eddies should also be included. Both conservation laws of circulation and orbital AM have been overlooked in previous theoretical studies. As a result of fusion during merging, the total eddy kinetic energy decreases slightly. In contrast, the total eddy potential energy (EPE) increases after merging. The increase in EPE is mostly supported by the loss of gravitational potential energy (PE) via eddy sinking below the original level prior to merging. This implies that the merging of eddies requires background gravitational PE to be converted to EPE. In contrast, the vorticity and enstrophy consequently decrease after merging. Thus, the eddy merging effect behaves as a “large-scale energy pump” in an inverse energy cascade. It is noted that eddy conservation and conversion laws depend on the laws of physical dynamics, even if additional degrees of freedom can be provided in a mathematical model.

Sign in / Sign up

Export Citation Format

Share Document