scholarly journals Embedded System for Motion Control of an Omnidirectional Mobile Robot

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 6722-6739 ◽  
Author(s):  
Md. Abdullah Al Mamun ◽  
Mohammad Tariq Nasir ◽  
Ahmad Khayyat
Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 48
Author(s):  
Mahmood Reza Azizi ◽  
Alireza Rastegarpanah ◽  
Rustam Stolkin

Motion control in dynamic environments is one of the most important problems in using mobile robots in collaboration with humans and other robots. In this paper, the motion control of a four-Mecanum-wheeled omnidirectional mobile robot (OMR) in dynamic environments is studied. The robot’s differential equations of motion are extracted using Kane’s method and converted to discrete state space form. A nonlinear model predictive control (NMPC) strategy is designed based on the derived mathematical model to stabilize the robot in desired positions and orientations. As a main contribution of this work, the velocity obstacles (VO) approach is reformulated to be introduced in the NMPC system to avoid the robot from collision with moving and fixed obstacles online. Considering the robot’s physical restrictions, the parameters and functions used in the designed control system and collision avoidance strategy are determined through stability and performance analysis and some criteria are established for calculating the best values of these parameters. The effectiveness of the proposed controller and collision avoidance strategy is evaluated through a series of computer simulations. The simulation results show that the proposed strategy is efficient in stabilizing the robot in the desired configuration and in avoiding collision with obstacles, even in narrow spaces and with complicated arrangements of obstacles.


Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 317 ◽  
Author(s):  
Raimarius Delgado ◽  
Byoung Choi

This paper proposes a real-time embedded system for joint space control of omnidirectional mobile robots. Actuators driving an omnidirectional mobile robot are connected in a line topology which requires synchronization to move simultaneously in translation and rotation. We employ EtherCAT, a real-time Ethernet network, to control servo controllers for the mobile robot. The first part of this study focuses on the design of a low-cost embedded system utilizing an open-source EtherCAT master. Although satisfying real-time constraints is critical, a desired trajectory on the center of the mobile robot should be decomposed into the joint space to drive the servo controllers. For the center of the robot, a convolution-based path planner and a corresponding joint space control algorithm are presented considering its physical limits. To avoid obstacles that introduce geometric constraints on the curved path, a trajectory generation algorithm considering high curvature turning points is adapted for an omnidirectional mobile robot. Tracking a high curvature path increases mathematical complexity, which requires precise synchronization between the actuators of the mobile robot. An improvement of the distributed clock—the synchronization mechanism of EtherCAT for slaves—is presented and applied to the joint controllers of the mobile robot. The local time of the EtherCAT master is dynamically adjusted according to the drift of the reference slave, which minimizes the synchronization error between each joint. Experiments are conducted on our own developed four-wheeled omnidirectional mobile robot. The experiment results confirm that the proposed system is very effective in real-time control applications for precise motion control of the robot even for tracking high curvature paths.


JURNAL ELTEK ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 108
Author(s):  
Muhammad Jodi Pamenang ◽  
Indrazno Siradjuddin ◽  
Budhy Setiawan

Tujuan mendasar dari kontrol gerak mobile robot adalah untuk mengarahkan robot ke posisi yang diberikan secara acak pada ruang 2D. Mobile robot dengan roda omni memiliki sifat holonomic di mana memiliki keunggulan kelincahan dan permasalahan pengendalian gerak hanya pada sisi aktuator, sedangkan mobile robot dengan roda konvensional, memiliki permasalahan tambahan pengendalian gerak dalam ruang area operasional robot. Karenanya, robot omni lebih gesit untuk bergerak dalam konfigurasi ruang area kerja apa pun. Makalah ini menyajikan model kontrol konvergensi eksponensial berbasis model untuk mobile robot omnidirectional roda empat. Kontrol yang diusulkan menjamin penurunan kesalahan secara eksponensial dari gerakan robot ke setiap posisi robot yang diinginkan. Pembahasan meliputi model kinematik dan kontrol dari robot bergerak omnidirectional roda empat dan eksperimen simulasi yang telah dilakukan untuk memverifikasi kinerja kontrol yang meliputi lintasan robot 2D, serta nilai error atau kesalahan pada kontrol robot. Hasil dari eksperimen simulasi menunjukkan keefektifan kontrol yang diusulkan. Mobile robot telah bergerak ke posisi yang diinginkan pada garis lurus dengan tujuan robot yang akurat dan niali error atau kesalahan yang didapat ialah |0.02735| serta grafik error telah menurun secara eksponensial.   The fundamental objective of a mobile robot motion control is to navigate the robot to any given arbitrary posture in which robot 2D location and its heading are concerned. Mobile robots with omni wheels have a holonomic properties the advantage is of agility and motion control problems only on the actuator, while mobile robots with conventional wheels, have a problem of motion control the robot in task space. Therefore, the omni-wheeled mobile robots are more agile to move in any task space configuration.  This paper presents a model based exponential convergence control law for a four-wheeled omnidirectional mobile robot. The proposed control law guarantees an exponential error decay of mobile robot motion to any given desired robot posture. The kinematic model and the control law of a four-wheeled omnidirectional mobile robot are discussed. Simulation experiments have been conducted to verify the control law performances which include the 2D robot trajectory, the error signals, and the robot control signals. Results from simulation experiments show the effectiveness of the proposed control law. Mobile robot has moved to the desired position in a straight line with the aim of the robot that is accurate and the error or error obtained is | 0.02735 | and the error graph has decreased exponentially


2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Ollin Peñaloza-Mejía ◽  
Luis A. Márquez-Martínez ◽  
Joaquín Alvarez ◽  
Miguel G. Villarreal-Cervantes ◽  
Ramón García-Hernández

A solution to achieve global asymptotic tracking with bounded velocities in an omnidirectional mobile robot is proposed in this paper. It is motivated by the need of having a useful in-practice motion control scheme, which takes into account the physical limits of the velocities. To this end, a passive nonlinear controller is designed and combined with a tracking controller in a negative feedback connection structure. By using Lyapunov theory and passivity tools, global asymptotic tracking with desired bounded velocities is proved. Simulations and experimental results are provided to show the effectiveness of the proposal.


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