Journal of Robotics, Networking and Artificial Life
Vol. 7(2); September (2020), pp. 125–128
DOI: https://doi.org/10.2991/jrnal.k.200528.011; ISSN 2405-9021; eISSN 2352-6386
https://www.atlantis-press.com/journals/jrnal

Research Article

Route Planning of Teleoperation Mobile Robot basedon the Virtual Reality Technology
Jiwu Wang, Xuechun Yuan*
School of Mechanical and Electronic Engineering, Beijing Jiaotong University, Haidian District, Beijing, China

ARTICLE INFOABSTRACT

Article History

Mobile teleoperation robot is one of the effective methods to help operators to work in complex environments. However, the timedelay by distance is a key factor that restricts its application. To solve this problem, the motion trajectory of the robot is simulatedusing virtual reality technology and the obtained optimization data are applied to control teleoperation robot.

Received 11 October 2019
Accepted 25 May 2020
Keywords
Teleoperation robot
virtual reality
route planning© 2020 The Authors. Published by Atlantis Press SARL.
This is an open access article distributed under the CC BY-NC 4.0 license (http://creativecommons.org/licenses/by-nc/4.0/).

1. INTRODUCTIONTeleoperation robots are one of the effective methods to help operators to work in complex environments (such as nuclear power
plants, underwater, space, etc.). However, one of the main problems
in teleoperation is the time delay [1]. Specifically, in actual work,
due to the distance between the operator’s side and the slave side of
the robot is far away, the communication will inevitably occur timedelay, resulting in the fact that the operator’s side and the slave sideof the robot cannot achieve synchronous action.
In order to solve this problem, the motion trajectory of the robot
is simulated by virtual reality technology and the obtained optimization data are applied to control teleoperation robot. In order toimprove the efficiency of simulation, a 3D simulation environmentof the real world is built in the unity 3D platform, and the physical model and kinematic model of the robot are established. At
the same time, the environmental conditions of various adjustableparameters such as light and material are simulated in the platform.
The physics engine for the robot is added in the simulation platform and the physical properties of the robot are configured.
Since there is no delay between the operator and the robot model,
the robot model can immediately respond to the operator’s input,
compensate for the influence of the delay, and assist the operator tocomplete the operation task smoothly and reliably.

2. THE CONSTRUCTION OF THE
VIRTUAL ENVIRONMENT
The vraisemblance of virtual environment construction is an
important guarantee to realize this project. Only by ensuring that
Corresponding author. Email: 18121262@bjtu.edu.cn*

the virtual world and the real world are as consistent as possible,
can we ensure the accuracy of our entire operation. The construction of the virtual environment is divided into the constructionof the robot model and the construction of the virtual simulation
environment.

2.1. Construction of the Robot Model
2.1.1. The construction of motion model
Wheeled mobile robot is an important branch of autonomous
mobile robot, which has the advantages of simple structure andeasy control. It is often used as a platform to study robot positioning, navigation, path planning and other technologies.
The mobile robot with two wheels differential drive is composedof vehicle body, power supply, control system and positioningsystem. By controlling the speed of the two driving wheels, therobot can track different trajectories: when the speed and direction of the two wheels are the same, the robot moves forward
in a straight line; when the speed of the two wheels is different,
the robot turns [2]. The rear wheels are two independent driving
wheels, while the front wheels are a universal wheel that can rollin any direction. The front wheel only plays a supporting role tokeep the body stable.
Its kinematic model is shown in Figure 1.
Take the midpoint of the center line of the left and right wheels as
the reference point. wL and wr are respectively the angular velocityof the left and right driving wheels. v and w are respectively thelinear velocity and angular velocity of rotation of the robot. r and L
are respectively the radius of the wheel and the distance between
the two wheels. In the derivation process, wr > wL is assumed, andits kinematic equation is shown as follows:126

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ì x = vcosq
ïï y = vsinq
ïq =w
ï
í
r (w L + wr ) ïv =2
ïr (w L - wr )ïïîw =L(1)2.1.2. The construction of physics model
The robot is modeled by SolidWorks 2010. First, models of the partsof the robot such as head, arm and joint are built, then these parts
are assembled. The assembly drawing is saved into the format of .stland imported into 3D max, as shown in Figure 2. After the model isoutput as .FBX format, it is imported into unity 3D for simulation,
as shown in Figure 3. After importing, set the physical properties
for the robot in unity 3D, add the rigidbody component to the robot
in unity 3D, and add the box collider component to each part.

First, multiple photos of the surrounding environment are collectedfrom the vision system of the end-robot, and the photos are transmitted to the ground control end. Then a three-dimensional model
is generated through Agisoft Photoscan software. Finally, the generated model is imported into unity 3D, and the light source is set
for the whole scene, material, and texture are set for the objects
in the scene. The Sunken Square of Beijing Jiaotong University ismodeled as an example, and the model after importing unity 3D
was shown in Figure 4.

3. PATH PLANNING OF ROBOTSIN VIRTUAL PLATFORM
Path planning is mainly implemented in unity 3D platform. First,
several obstacles are set up in the scene. The four orange cuboids
in Figure 5 simulate obstacles. What we want to achieve is that byclicking on any position on the ground with the mouse, the robot
can avoid obstacles and successfully reach the mouse click point.
In this process, the walking track of the robot is displayed, and the2.2. Construction of the Virtual
Simulation Environment
Virtual environment modeling is realized by synthesizing twodimensional environment images into three-dimensional models.

Figure 1 | Motion model of a mobile robot.

Figure 2 | The robot model in 3D max imported from SolidWorks.

Figure 3 | The components of the robot in unity 3D imported from3D max.

Figure 4 | The model in unity 3D imported from 3D max.

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Figure 5 | The walkable area of the robot.

Figure 7 | The operation result after improvement the scene runs.

Figure 8 | The trajectory of the robot in the xz-plane.

4. CONCLUSION

Figure 6 | The three-dimensional coordinates of the robot in motion.

three-dimensional coordinates of the walking track point of therobot are output to a .TXT file.
To realize the obstacle avoidance function of the robot, the pathfinding plug-in navigation that comes with unity is used to realize
automatic path finding through a series of calculations.
First, we baked the walking area of the robot, as shown in the blue
area in Figure 6, and added the Nav Mesh Agent component for
the robot to set the speed and acceleration of the robot and otherparameters.
Write C# script and attach it to the robot to realize the functionof mouse clicking on the ground robot to avoid obstacles andreach the target point, and add Line Render component to automatically draw the robot’s walking track when the robot moves
through the script. Use the StreamWriter class in C# to output
real-time 3D coordinates of the robot as it moves to a .txt file, as
shown in Figure 6.
After the scene runs, the effect is shown in Figure 7. We canalso zoom in and out the mobile scene through the middle
mouse button.
Draw the exported data points on the xz-plane with Matlab, asshown in Figure 8.

In this paper, the robot motion simulation platform is built in the virtual reality environment. With this platform, the robot’s motion trajectory was simulated for any specified target points. At the same time, theobstacle avoidance strategy was also tested in that platform. The satisfactory results were obtained. After the simulation, the true moving
trajectory in the true environments for the robot is gotten. Then thetrue robot can be controlled to move based on the above data. In thecoming future, the robot will be verified with the simulation data.

CONFLICTS OF INTEREST
The authors declare they have no conflicts of interest.

ACKNOWLEDGMENT
The paper is supported by project M18GY300021.

REFERENCES[1] A.K. Bejczy, W.S. Kim, S.C. Venema, The phantom robot: predictive displays for teleoperation with time delay, Proceedings ofthe IEEE International Conference on Robotics and Automation,IEEE, Cincinnati, OH, USA, 1990, pp. 546–551.
[2] F. Pourboghrat, M.P. Karlsson, Adaptive control of dynamic
mobile robots with nonholonomic constraints, Comput. Electr.
Eng. 28 (2002), 241–253.

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AUTHORS INTRODUCTION
Ms. Yuan Xuechun

Dr. Wang Jiwu
He is an associate professor, Beijing
Jiaotong University. His research interests
are Intelligent Robot, Machine Vision, andImage Processing.

She is a postgraduate in Beijing Jiaotong
University. Her research interests are Virtual
Reality and image processing.