Optimal Synthesis of a Planar Reactionless Three-Degree-of-Freedom Parallel Mechanism

2011 ◽  
Vol 3 (4) ◽  
Author(s):  
Jean-François Collard ◽  
Clément Gosselin
Keyword(s):  
Power Consumption ◽  
Interesting Property ◽  
Degree Of Freedom ◽  
Design Parameters ◽  
Sensitivity Index ◽  
Optimization Approach ◽  
Counter Rotation ◽  
Kinematic Sensitivity ◽  
Global Moment ◽  
Three Degree Of Freedom

A reactionless mechanism is one in which no reaction forces nor moments are transmitted to the base for any arbitrary motion. This interesting property often requires to increase the total mass and the moments of inertia, leading to reduced dynamical performances. Therefore, this paper presents an optimization approach to synthesize and improve the dynamical performance of a reactionless three-degree-of-freedom planar mechanism. The three legs of this original mechanism are composed of reactionless four-bar mechanisms dynamically balanced with only one counter-rotation at the base. The optimization variables are the geometric and inertial parameters, whereas the goal is to minimize the global moment of inertia of each leg. This will reduce the power consumption of the three actuators and increase the agility. To meet physical and realistic requirements, the optimization problem is also constrained with bounds on the parameters, with the reachability of a given workspace and with a given range on a kinematic sensitivity index. Since different initial guesses of the optimization process lead to similar objective results, it is proposed to search for several local solutions (morphologies). A methodology is therefore developed to explore the design space and group the results after refinement. The final choice among the obtained solutions is made using additional design criteria based on the sensitivity in terms of dynamic balancing and power consumption with respect to the design parameters.

Optimal Synthesis of a Planar Reactionless Three-Degree-of-Freedom Parallel Mechanism

2010 ◽  
Author(s):  
Jean-Francois Collard ◽  
Cle´ment Gosselin
Keyword(s):  
Power Consumption ◽  
Interesting Property ◽  
Degree Of Freedom ◽  
Design Parameters ◽  
Sensitivity Index ◽  
Optimization Approach ◽  
Counter Rotation ◽  
Kinematic Sensitivity ◽  
Global Moment ◽  
Three Degree Of Freedom

A reactionless mechanism is one in which no reaction forces nor moments are transmitted to the base for any arbitrary motion. This interesting property often requires to increase the total mass and the moments of inertia, leading to reduced dynamical performances. Therefore, this paper presents an optimization approach to synthesize and improve the dynamical performance of a reactionless three-degree-of-freedom planar mechanism. The three legs of this original mechanism are composed of reactionless four-bar mechanisms dynamically balanced with only one counter-rotation at the base. The optimization variables are the geometric and inertial parameters, while the goal is to minimize the global moment of inertia of each leg. This will reduce the power consumption of the three actuators and increase the agility. To meet physical and realistic requirements, the optimization problem is also constrained with bounds on the parameters, with the reachability of a given workspace and with a given range on a kinematic sensitivity index. Since different initial guesses of the optimization lead to similar objective results, it is proposed to search for several local solutions (morphologies) in the design space. The final choice among these solutions is made using additional design criteria based on the sensitivity in terms of dynamic balancing and power consumption with respect to the design parameters.

Dynamic Trajectory Planning and Geometric Analysis of a Two-Degree-of-Freedom Translational Cable-Suspended Planar Parallel Robot Using a Parallelogram Cable Loop

2019 ◽  
Vol 11 (2) ◽  
Author(s):  
Jordan M. Longval ◽  
Clément Gosselin
Keyword(s):  
Trajectory Planning ◽  
Geometric Analysis ◽  
Parallel Robot ◽  
Design Parameters ◽  
Sensitivity Index ◽  
General Elliptic ◽  
Planning Approach ◽  
Kinematic Sensitivity ◽  
Two Degree Of Freedom ◽  
Dynamic Trajectory

This paper presents a trajectory planning approach and an analysis of the geometric design parameters for a planar cable-suspended translational parallel robot based on a parallelogram cable loop. The cable robot produces purely translational movements in a planar workspace. Furthermore, this special architecture only requires two actuators, which make it fully actuated. From the dynamic model of the robot, general algebraic inequalities are obtained that ensure that the cables remain taut. A general elliptic trajectory is then defined and substituted into the algebraic inequalities to obtain conditions on the geometrical design parameters that ensure that the cables are always in tension. In addition, a special trajectory-specific oscillation frequency emerges and enables the end effector to dynamically move beyond the boundaries of the static workspace, thus expanding the workspace of the mechanism. Finally, a kinematic sensitivity index is studied in order to determine if the parallelogram structure has any influence on the rotational sensitivity of the mechanism.

On the Lateral Stability and Control of the Automobile as Influenced by the Dynamics of the Steering System

1966 ◽  
Vol 88 (3) ◽  
pp. 283-294 ◽  
Author(s):  
Leonard Segel
Keyword(s):  
Degrees Of Freedom ◽  
Steering System ◽  
Degree Of Freedom ◽  
Design Parameters ◽  
Steering Wheel ◽  
Directional Control ◽  
Natural Modes Of Motion ◽  
Three Degree Of Freedom ◽  
And Control ◽  
Automobile Use

Measurements of the directional response of an automobile to torque inputs applied at the steering wheel are compared with predictions yielded by a five-degree-of-freedom model of a four-wheeled, pneumatic-tired vehicle. This comparison demonstrates that the directional control and stability of the “free-control” automobile is satisfactorily characterized by the addition of a quasilinear representation of a steering system (i.e., a mechanism having two degrees of freedom with Coulomb friction introduced as the single nonlinear element) to a linear three-degree-of-freedom representation of the “fixed-control” automobile. Use is made of the experimentally substantiated five-degree-of-freedom mathematical model to study the relationship between automotive design parameters and the response and stability in each of the four natural modes of motion that exist for the free-control vehicle.

Dynamic Trajectory Planning and Geometric Design of a Two-DOF Translational Cable-Suspended Planar Parallel Robot Using a Parallelogram Cable Loop

2018 ◽  
Author(s):  
Jordan M. Longval ◽  
Clément Gosselin
Keyword(s):  
Trajectory Planning ◽  
Parallel Robot ◽  
Geometric Design ◽  
Rotational Stability ◽  
Design Parameters ◽  
Sensitivity Index ◽  
General Elliptic ◽  
Planning Approach ◽  
Kinematic Sensitivity ◽  
Dynamic Trajectory

This paper presents a trajectory planning approach and an analysis of the geometric design parameters for a planar cable-suspended translational parallel robot based on a parallelogram cable loop. The cable robot produces purely translational movements in a planar workspace. Furthermore, this special architecture only requires two actuators which makes it fully actuated. From the dynamic model of the robot, general algebraic inequalities are obtained that ensure that the cables remain taut. A general elliptic trajectory is then defined and substituted into the algebraic inequalities to obtain conditions on the geometrical design parameters that ensure that the cables are always in tension. In addition, a special trajectory-specific oscillation frequency emerges and enables the end-effector to dynamically move beyond the boundaries of the static workspace, thus expanding the workspace of the mechanism. Finally, a kinematic sensitivity index is studied in order to assess the influence of the parallelogram structure on the rotational stability of the mechanism.

Experimental Validation of a Three-Degree-of-Freedom Cable-Suspended Parallel Robot for Spatial Translation With Constant Orientation

2019 ◽  
Vol 11 (2) ◽  
Author(s):  
Dinh-Son Vu ◽  
Eric Barnett ◽  
Clément Gosselin
Keyword(s):  
Experimental Validation ◽  
Parallel Robot ◽  
Degree Of Freedom ◽  
Proof Of Concept ◽  
Kinematic Modeling ◽  
End Effector ◽  
Cartesian Space ◽  
Positioning Errors ◽  
Kinematic Sensitivity ◽  
Three Degree Of Freedom

This paper shows an experimental validation for the design of a three-degree-of-freedom (DOF) cable-suspended parallel robot, which has six cables attached to the end-effector, arranged in three pairs, with each pair being driven by a single motor. For each pair, the moving platform attachment points and the winch cable guides on the fixed frame form a parallelogram, an arrangement that allows the end-effector to be positioned throughout its static workspace (SW) while maintaining a constant orientation. In this paper, the kinematic modeling of the robot is first described, along with its SW. Then, the robot's kinematic sensitivity is assessed in position and orientation such that an upper bound is found for the amplification of the cable positioning errors in Cartesian space. Finally, experimental results obtained using a proof-of-concept mechanism are described, which confirm the claim that the proposed design maintains a constant platform orientation in the SW.

scholarly journals Towards an Efficient CNN Inference Architecture Enabling In-Sensor Processing

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1955
Author(s):  
Md Jubaer Hossain Pantho ◽  
Pankaj Bhowmik ◽  
Christophe Bobda
Keyword(s):  
Power Consumption ◽  
High Speed ◽  
Image Sensor ◽  
Machine Learning Algorithms ◽  
Hierarchical Optimization ◽  
Computation Method ◽  
Optimization Approach ◽  
Efficient Computation ◽  
Feature Maps ◽  
Dynamic Power

The astounding development of optical sensing imaging technology, coupled with the impressive improvements in machine learning algorithms, has increased our ability to understand and extract information from scenic events. In most cases, Convolution neural networks (CNNs) are largely adopted to infer knowledge due to their surprising success in automation, surveillance, and many other application domains. However, the convolution operations’ overwhelming computation demand has somewhat limited their use in remote sensing edge devices. In these platforms, real-time processing remains a challenging task due to the tight constraints on resources and power. Here, the transfer and processing of non-relevant image pixels act as a bottleneck on the entire system. It is possible to overcome this bottleneck by exploiting the high bandwidth available at the sensor interface by designing a CNN inference architecture near the sensor. This paper presents an attention-based pixel processing architecture to facilitate the CNN inference near the image sensor. We propose an efficient computation method to reduce the dynamic power by decreasing the overall computation of the convolution operations. The proposed method reduces redundancies by using a hierarchical optimization approach. The approach minimizes power consumption for convolution operations by exploiting the Spatio-temporal redundancies found in the incoming feature maps and performs computations only on selected regions based on their relevance score. The proposed design addresses problems related to the mapping of computations onto an array of processing elements (PEs) and introduces a suitable network structure for communication. The PEs are highly optimized to provide low latency and power for CNN applications. While designing the model, we exploit the concepts of biological vision systems to reduce computation and energy. We prototype the model in a Virtex UltraScale+ FPGA and implement it in Application Specific Integrated Circuit (ASIC) using the TSMC 90nm technology library. The results suggest that the proposed architecture significantly reduces dynamic power consumption and achieves high-speed up surpassing existing embedded processors’ computational capabilities.

scholarly journals Development of a Compound Speckle Interferometer for Precision Three-Degree-of-Freedom Displacement Measurement

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1828
Author(s):  
Hung-Lin Hsieh ◽  
Bo-Yen Sun
Keyword(s):  
Speckle Interferometry ◽  
Degree Of Freedom ◽  
Heterodyne Interferometry ◽  
Beam Splitting ◽  
Speckle Interferometer ◽  
Real World Applications ◽  
Three Degree Of Freedom ◽  
Contact Displacement ◽  
Displacement Measurements ◽  
Measurement Capabilities

In this study, a compound speckle interferometer for measuring three-degree-of-freedom (3-DOF) displacement is proposed. The system, which combines heterodyne interferometry, speckle interferometry and beam splitting techniques, can perform precision 3-DOF displacement measurements, while still having the advantages of high resolution and a relatively simple configuration. The incorporation of speckle interferometry allows for non-contact displacement measurements by detecting the phase of the speckle interference pattern formed from the convergence of laser beams on the measured rough surface. Experiments were conducted to verify the measurement capabilities of the system, and the results show that the proposed system has excellent measurement capabilities suitable for future real-world applications.

scholarly journals Analytical Investigation on Torque of Three-Degree-of-Freedom Electromagnetic Actuator for Image Stabilization

2021 ◽  
Vol 11 (15) ◽  
pp. 6872
Author(s):  
Chien-Sheng Liu ◽  
Yi-Hsuan Lin ◽  
Chiu-Nung Yeh
Keyword(s):  
Power Efficiency ◽  
Rotation Angle ◽  
Analytical Investigation ◽  
Degree Of Freedom ◽  
Electromagnetic Actuator ◽  
3D Fem ◽  
Image Stabilization ◽  
Large Rotation ◽  
Spherical Motor ◽  
Three Degree Of Freedom

In keeping with consumers’ preferences for electromagnetic motors of ever smaller power consumption, it is necessary to improve the power efficiency of the electromagnetic motors used in unmanned aerial vehicles and robots without sacrificing their performance. Three-degree-of-freedom (3-DOF) spherical motors have been developed for these applications. Accordingly, this study modifies the 3-DOF spherical motor proposed by Hirata’s group in a previous study (Heya, A.; Hirata, K.; Niguchi, N., Dynamic modeling and control of three-degree-of-freedom electromagnetic actuator for image stabilization, IEEE Transactions on Magnetics 2018, 54, 8207905.) to accomplish a 3-DOF spherical motor for camera module with higher torque output in the large rotation angle. The main contribution of this study is to improve the static torque in the X- and Y-axes with an improved electromagnetic structure and a particular controlling strategy. In the structural design, eight symmetrical coils with specific coil combination are used instead of conventional four symmetrical coils. In this study, the development of the proposed 3-DOF spherical motor was constructed and verified by using a 3D finite-element method (3D FEM). The simulation results show that the proposed 3-DOF spherical motor has higher torque output in the large rotation angle when compared to the original 3-DOF spherical motor.

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