scholarly journals Design and Analysis of an Intelligent Toilet Wheelchair Based on Planar 2DOF Parallel Mechanism with Coupling Branch Chains

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2677
Author(s):  
Xiaohua Shi ◽  
Hao Lu ◽  
Ziming Chen
Keyword(s):  
Parallel Mechanism ◽  
Weighted Average ◽  
Degree Of Freedom ◽  
Height Range ◽  
Seat Height ◽  
Driving Mode ◽  
Manual Adjustment ◽  
General Rules ◽  
Before And After ◽  
Two Degree Of Freedom

Due to the fixed size of the structure or the possibility of only simple manual adjustment, the traditional toilet wheelchair cannot easily be adapted to the size of the user or the toilet. In this paper, a planar two-degree-of-freedom parallel mechanism with coupling branch chains is proposed to enable both seat height adjustment and body posture adjustment of a toilet chair, solving the problems of posture adaptability between the user and the machine, and height matching in the process of using the wheelchair-assisted toilet. The model of the parallel mechanism was designed after analyzing the general rules of posture transformation in the human body before and after the toilet process, and the dimensions of each linkage were then determined according to the constraint conditions. By analyzing the degree of freedom, kinematics, workspace, singularity and position of the center of gravity, the rationality of the design was ensured. The weighted average function was used to find the optimal fixed point of the horizontal moving slider, and the actual trajectory at the end of the single driving mode was close to the ideal trajectory. The experimental results show that the adjustable seat height range is 290~550 mm and the adjustable angle range is 0~90°, which can enable disabled people to use the toilet independently.

Dynamics of a Two-DOF Parallel Pointing Mechanism

2005 ◽  
Author(s):  
Alessandro Cammarata ◽  
Rosario Sinatra
Keyword(s):  
Numerical Simulation ◽  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Kinematic Model ◽  
Degree Of Freedom ◽  
Numerical Examples ◽  
Proposed Model ◽  
Dynamic Analyses ◽  
Moving Platform ◽  
Two Degree Of Freedom

This paper presents kinematic and dynamic analyses of a two-degree-of-freedom pointing parallel mechanism. The mechanism consists of a moving platform, connected to a fixed platform by two legs of type PUS (prismatic-universal-spherical). At first a simplified kinematic model of the pointing mechanism is introduced. Based on this proposed model, the dynamics equations of the system using the Natural Orthogonal Complement method are developed. Numerical examples of the inverse dynamics results are presented by numerical simulation.

Reactionless Two-Degree-of-Freedom Planar Parallel Mechanism With Variable Payload

2009 ◽  
Author(s):  
Alexandre Lecours ◽  
Cle´ment Gosselin
Keyword(s):  
Dynamic Simulation ◽  
Parallel Mechanism ◽  
Reaction Force ◽  
Simulation Software ◽  
Degree Of Freedom ◽  
Dynamic Balancing ◽  
End Effector ◽  
Planar Mechanism ◽  
Two Degree Of Freedom ◽  
Arbitrary Trajectory

A reactionless mechanism is one which does not exert any reaction force or moment on its base at all times, for any arbitrary trajectory of the mechanism. This paper addresses the static and dynamic balancing of a two-degree-of-freedom parallel planar mechanism (five-bar mechanism). A simple and effective adaptive balancing method is presented that allows the mechanism to maintain the reactionless condition for a range of payloads. Important proofs concerning the balancing of five-bar mechanisms are also presented. The design of a real mechanism where parallelogram linkages are used to produce pure translations at the end-effector is also presented. Finally, using dynamic simulation software, it is shown that the mechanism is reactionless for arbitrarily chosen trajectories and for a variety of payloads.

Design and Experimental Validation of a Two-Degree-of-Freedom Force Illusion Device

2014 ◽  
Author(s):  
Nicolò Pedemonte ◽  
Frédérik Berthiaume ◽  
Thierry Laliberté ◽  
Clément Gosselin
Keyword(s):  
External Force ◽  
Parallel Mechanism ◽  
Visually Impaired ◽  
Experimental Validation ◽  
Degree Of Freedom ◽  
Haptic Device ◽  
Visually Impaired People ◽  
Impaired People ◽  
Two Degree Of Freedom

In this paper, a new hand-held haptic device that aims at producing the illusion of an external force is presented. This device is based on a planar two-degree-of-freedom parallel mechanism that can be programmed to produce the force illusion in any direction of the plane. Two tests are proposed to a group of people, in order to evaluate the device’s capabilities. The results obtained from the tests are analyzed and shown to be promising. Finally, modifications to the device are proposed in order to further improve the effectiveness of the system. The device proposed in this work is envisioned as a guidance tool for visually impaired people.

Two-Degree-of-Freedom Decoupled Nonredundant Cable-Loop-Driven Parallel Mechanism

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
Hanwei Liu ◽  
Clément Gosselin ◽  
Thierry Laliberté
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
The Other ◽  
End Effector ◽  
Two Degrees Of Freedom ◽  
Actuation Redundancy ◽  
Rigid Link ◽  
Force Closure ◽  
Two Degree Of Freedom

A novel two-degree-of-freedom (DOF) cable-loop slider-driven parallel mechanism is introduced in this paper. The novelty of the mechanism lies in the fact that no passive rigid-link mechanism or springs are needed to support the end-effector (only cables are connected to the end-effector) while at the same time there is no actuation redundancy in the mechanism. Sliders located on the edges of the workspace are used and actuation redundancy is eliminated while providing force closure everywhere in the workspace. It is shown that the two degrees of freedom of the mechanism are decoupled and only two actuators are needed to control the motion. There are two cable loops for each direction of motion: one acts as the actuating loop while the other is the constraint loop. Due to the simple geometric design, the kinematic and static equations of the mechanism are very compact. The stiffness of the mechanism is also analyzed in the paper. It can be observed that the mechanism's stiffness is much higher than the stiffness of the cables. The proposed mechanism's workspace is essentially equal to its footprint and there are no singularities.

Singularity Analysis of a New 2-DOF Parallel Tilter

2012 ◽  
Vol 224 ◽  
pp. 504-509
Author(s):  
Hai Dong Wang ◽  
Jing Sun ◽  
Yu Quan Bi ◽  
Mao Sheng Yang
Keyword(s):  
Parallel Mechanism ◽  
Jacobian Matrix ◽  
Singularity Analysis ◽  
Degree Of Freedom ◽  
Coordinate Transformations ◽  
Analytic Equation ◽  
Singular Configuration ◽  
Two Degree Of Freedom

One type of spatial new parallel mechanism with two degree of freedom is proposed.. The position and velocity analytic equation are constructed based on the coordinate transformations. Finally, the singular configuration of the tilter is analyzed by the forward and the inverse Jacobian matrix.

Kinematic Design of a Novel Two Degree-of-Freedom Parallel Mechanism for Minimally Invasive Surgery

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Wen-ao Cao ◽  
Shi-jie Xu ◽  
Kun Rao ◽  
Tengfei Ding
Keyword(s):  
Minimally Invasive Surgery ◽  
Minimally Invasive ◽  
Parallel Mechanism ◽  
Screw Theory ◽  
Degree Of Freedom ◽  
Compact Structure ◽  
Minimally Invasive Surgical ◽  
Physical Prototype ◽  
Two Degree Of Freedom ◽  
Surgical Manipulator

A novel two degree-of-freedom (2-DOF) parallel mechanism with remote center-of-motion (RCM) is proposed for minimally invasive surgical applications in this paper. A surgical manipulator with expected three-rotation and one-translation (3R1T) outputs can be obtained by serially connecting a revolute pair (R) and a prismatic pair (P) to the mechanism. First, kinematics of the new mechanism is analyzed and the corresponding velocity Jacobin matrix is established. Then, singularity identification of the mechanism is performed based on screw theory. Further, main dimensions of the mechanism are designed, and a physical prototype is developed to verify the effectiveness of executing RCM. The proposed mechanism has relatively simple kinematics, and can obtain a noninterference and nonsingularity cone workspace with the top angle of 60 deg based on a compact structure.

scholarly journals Motion Characteristics Analysis of a Novel Spherical Two-degree-of-freedom Parallel Mechanism

2021 ◽  
Author(s):  
Chen Ziming ◽  
Chen Xuechan ◽  
Gao Min ◽  
Zhao Chen ◽  
Zhao Kun ◽  
...  
Keyword(s):  
Motion Planning ◽  
Inverse Kinematics ◽  
Parallel Mechanism ◽  
Degree Of Freedom ◽  
Practical Application ◽  
Continuous Rotation ◽  
Characteristics Analysis ◽  
Spherical Parallel Mechanism ◽  
Motion Characteristics ◽  
Two Degree Of Freedom

Abstract In this paper, a novel two-degree-of-freedom (2DOF) spherical parallel mechanism(SPM) with symmetrical structure is proposed and analyzed. First, the models of forward kinematics and inverse kinematics are established based on D-H parameters, and the Jacobian matrix of the mechanism is obtained and verified. Second, the workspace of the mechanism is obtained according to inverse kinematics and link interference conditions. Next, rotational characteristics analysis shows that the end effector can achieve continuous rotation about an axis located in the mid-plane and passing through the rotation center of the mechanism. Moreover, the rotational characteristics of the mechanism are proved and motion planning is carried out. A numerical example is given to verify the kinematics analysis and motion planning. Finally, some variant mechanisms can be synthesized. This work lays the foundation for the motion control and practical application of this 2DOF SPM.

Reactionless Two-Degree-of-Freedom Planar Parallel Mechanism With Variable Payload

2010 ◽  
Vol 2 (4) ◽  
Author(s):  
Alexandre Lecours ◽  
Clément Gosselin
Keyword(s):  
Dynamic Simulation ◽  
Parallel Mechanism ◽  
Reaction Force ◽  
Simulation Software ◽  
Degree Of Freedom ◽  
Dynamic Balancing ◽  
End Effector ◽  
Planar Mechanism ◽  
Two Degree Of Freedom ◽  
Arbitrary Trajectory

A reactionless mechanism is one that does not exert any reaction force or moment on its base at all times, for any arbitrary trajectory of the mechanism. This paper addresses the static and dynamic balancing of a two-degree-of-freedom parallel planar mechanism (five-bar mechanism). A simple and effective adaptive balancing method is presented that allows the mechanism to maintain the reactionless condition for a range of payloads. Important proofs concerning the balancing of five-bar mechanisms are also presented. The design of a real mechanism where parallelogram linkages are used to produce pure translations at the end-effector is also presented. Finally, using dynamic simulation software, it is shown that the mechanism is reactionless for arbitrarily chosen trajectories and for a variety of payloads.

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