Velocity Constraints Based Online Trajectory Planning for High-Speed Parallel Robots

Considering the real-time control of a high-speed parallel robot, a concise and precise dynamics model is essential for the design of the dynamics controller. However, the complete rigid-body dynamics model of parallel robots is too complex for online calculation. Therefore, a hierarchical approach for dynamics model simplification, which considers the kinematics performance, is proposed in this paper. Firstly, considering the motion smoothness of the end-effector, trajectory planning based on the workspace discretization is carried out. Then, the effects of the trajectory parameters and acceleration types on the trajectory planning are discussed. But for the fifth-order and seventh-order B-spline acceleration types, the trajectory will generate excessive deformation after trajectory planning. Therefore, a comprehensive index that considers both the motion smoothness and trajectory deformation is proposed. Finally, the dynamics model simplification method based on the combined mass distribution coefficients is studied. Results show that the hierarchical approach can guarantee both the excellent kinematics performance of the parallel robot and the accuracy of the simplified dynamics model under different trajectory parameters and acceleration types. Meanwhile, the method proposed in the paper can be applied to the design of the dynamics controller to enhance the robot's performance.

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Performance simulation and energetic analysis of TBot high-speed cable-driven parallel robot

Journal of Mechanisms and Robotics ◽

10.1115/1.4052322 ◽

2021 ◽

pp. 1-14

Author(s):

Jinhao Duan ◽

Zhufeng Shao ◽

Zhaokun Zhang ◽

Fazhong Peng

Keyword(s):

Energy Consumption ◽

Trajectory Planning ◽

High Speed ◽

Low Cost ◽

Parallel Robot ◽

Industrial Applications ◽

Parallel Robots ◽

Dynamics Modeling ◽

Serial Robots ◽

Key Issues

Abstract Compared with serial robots, parallel robots have the advantages of high stiffness and good dynamics. By replacing the rigid limbs with cables, the cable-driven parallel robot (CDPR) is greatly simplified in structure and lightweight. We designed a high-speed CDPR tensioned by the passive rod and spring, named TBot. The robot can realize the SCARA movement as the classical Delta parallel robot. Comparison analysis of TBot and Delta is carried out to reveal the natures of the CDPRs and rigid parallel robots, identify the key issues, and promote industrial applications. Based on kinematics and dynamics modeling, performances are analyzed with simulation under a typical Adept Motion trajectory. Results illustrate that TBot has advantages of low cost, low inertia, low energy consumption and adjustable workspace and has great application potential. Energy consumption of the TBot is discussed and the trajectory planning is studied with the genetic algorithm to further reduce the energy consumption, considering the influence of the passive spring. Finally, on the basis of 30% less energy consumption for the Adept Motion than Delta, extra 14.3% energy consumption is saved through the trajectory planning of TBot.

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Trajectory Planning for Autonomous High-Speed Overtaking using MPC with Terminal Set Constraints

2018 21st International Conference on Intelligent Transportation Systems (ITSC) ◽

10.1109/itsc.2018.8569529 ◽

2018 ◽

Cited By ~ 6

Author(s):

Shilp Dixit ◽

Umberto Montanaro ◽

Saber Fallah ◽

Mehrdad Dianati ◽

David Oxtoby ◽

...

Keyword(s):

Trajectory Planning ◽

High Speed ◽

Set Constraints ◽

Terminal Set

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Trajectory Planning in UAV Emergency Networks with Potential Underlaying D2D Communication Based on K-means

10.21203/rs.3.rs-144554/v1 ◽

2021 ◽

Author(s):

Shuo Zhang ◽

Shuo Shi ◽

Tianming Feng ◽

Xuemai Gu

Keyword(s):

Trajectory Planning ◽

Communication Systems ◽

High Speed ◽

Large Scale ◽

High Reliability ◽

Base Station ◽

Planning Problem ◽

Communication Signal ◽

User Coverage ◽

Trajectory Length

Abstract Unmanned aerial vehicles (UAVs) have been widely used in communication systems due to excellent maneuverability and mobility. The ultra-high speed, ultra-low latency, and ultra-high reliability of 5th generation wireless systems (5G) have further promoted vigorous development of UAVs. Compared with traditional means of communication, UAV can provide services for ground terminal without time and space constraints, so it is often used as air base station (BS). Especially in emergency communications and rescue, it provides temporary communication signal coverage service for disaster areas. In the face of large-scale and scattered user coverage tasks, UAV's trajectory is an important factor affecting its energy consumption and communication performance. In this paper, we consider a UAV emergency communication network where UAV aims to achieve complete coverage of potential underlying D2D users (DUs). The trajectory planning problem is transformed into the deployment and connection problem of stop points (SPs). Aiming at trajectory length and sum throughput, two trajectory planning algorithms based on K-means are proposed. Due to the non-convexity of sum throughput optimization, we present a sub-optimal solution by using the successive convex approximation (SCA) method. In order to balance the relationship between trajectory length and sum throughput, we propose a joint evaluation index which is used as an objective function to further optimize trajectory. Simulation results show the validity of the proposed algorithms which have advantages over the well-known benchmark scheme in terms of trajectory length and sum throughput.

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Modal Kinematic Analysis of a Parallel Kinematic Robot with Low-Stiffness Transmissions

Robotics ◽

10.3390/robotics10040132 ◽

2021 ◽

Vol 10 (4) ◽

pp. 132

Author(s):

Paolo Righettini ◽

Roberto Strada ◽

Filippo Cortinovis

Keyword(s):

High Speed ◽

Parallel Robots ◽

Maximum Speed ◽

Kinematic Structure ◽

End Effector ◽

New Approach ◽

Working Space ◽

Modes Of Vibration ◽

Parallel Kinematic ◽

Actuated Joints

Several industrial robotic applications that require high speed or high stiffness-to-inertia ratios use parallel kinematic robots. In the cases where the critical point of the application is the speed, the compliance of the main mechanical transmissions placed between the actuators and the parallel kinematic structure can be significantly higher than that of the parallel kinematic structure itself. This paper deals with this kind of system, where the overall performance depends on the maximum speed and on the dynamic behavior. Our research proposes a new approach for the investigation of the modes of vibration of the end-effector placed on the robot structure for a system where the transmission’s compliance is not negligible in relation to the flexibility of the parallel kinematic structure. The approach considers the kinematic and dynamic coupling due to the parallel kinematic structure, the system’s mass distribution and the transmission’s stiffness. In the literature, several papers deal with the dynamic vibration analysis of parallel robots. Some of these also consider the transmissions between the motors and the actuated joints. However, these works mainly deal with the modal analysis of the robot’s mechanical structure or the displacement analysis of the transmission’s effects on the positioning error of the end-effector. The discussion of the proposed approach takes into consideration a linear delta robot. The results show that the system’s natural frequencies and the directions of the end-effector’s modal displacements strongly depend on its position in the working space.

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Modelling and Simulation of a Isoglide T3R1 Parallel Robot

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.166-167.457 ◽

2010 ◽

Vol 166-167 ◽

pp. 457-462

Author(s):

Dan Verdes ◽

Radu Balan ◽

Máthé Koppány

Keyword(s):

High Speed ◽

Degrees Of Freedom ◽

Parallel Robot ◽

Parallel Robots ◽

Practical Implementation ◽

Medical Robots ◽

The Past ◽

And Control ◽

Workspace Design ◽

Human Systems

Parallel robots find many applications in human-systems interaction, medical robots, rehabilitation, exoskeletons, to name a few. These applications are characterized by many imperatives, with robust precision and dynamic workspace computation as the two ultimate ones. This paper presents kinematic analysis, workspace, design and control to 3 degrees of freedom (DOF) parallel robots. Parallel robots have received considerable attention from both researchers and manufacturers over the past years because of their potential for high stiffness, low inertia and high speed capability. Therefore, the 3 DOF translation parallel robots provide high potential and good prospects for their practical implementation in human-systems interaction.

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