UWE Bristol Engineering showcase 2015
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Gytis Bernotas<br />
BEng Robotics<br />
Project Supervisor<br />
Dr Matthew Studley and Dr Paul Bremner<br />
Tele-operation and blended-control<br />
Introduction<br />
Due to technologies that create<br />
convenient life there are a lot more<br />
people in the World than it used to<br />
be in the past, and the number<br />
keeps progressively increasing -<br />
over the last 60 years our<br />
population has increased over 2.8<br />
times. Moreover, due to the<br />
economic changes in our lives<br />
urbanization process has taken<br />
action. It was calculated that by the<br />
end of 2008 half of the population<br />
lived in urban areas and it is<br />
estimated that by 2050 86% of<br />
developed world and 64% of the<br />
developing world would be<br />
urbanized. In order to reduce living<br />
area, but increase the number of<br />
people that could be inhabited in<br />
the cities people started building<br />
skyscrapers. However, as the<br />
skyscrapers’ heights keep increasing<br />
the number of workers is<br />
decreasing – 25% of all deaths<br />
across all industry sectors in Europe<br />
are due to people working at<br />
height. One solution to this problem<br />
might be achieved by involving<br />
robots into building workforce. One<br />
field of robotics that has been used<br />
and developed since 1940's and is<br />
directly interlaced with humans is<br />
telerobotics.<br />
Tele-operation and blended-control<br />
involves 3 fields: Machine Vision,<br />
Tracking and Robotics. Finally, each<br />
component will be connected in<br />
order to form a fully working<br />
tele-operation system.<br />
Machine Vision<br />
The main goal of Machine Vision is<br />
identify and find objects positions<br />
and orientation in robotic arm’s<br />
workspace that will make<br />
collaborative/blended control<br />
possible. Robust and accurate<br />
system has been created through<br />
the adoption of Method of<br />
Moments algorithm.<br />
Tracking<br />
Since the beginning of teleoperation<br />
different mechanical<br />
devices were used such as<br />
mechanical master-slave tele<br />
manipulators, joysticks, dials,<br />
mouse movements and<br />
exoskeletons. Nonetheless, they are<br />
not comfortable and user has to<br />
learn how to use them. However, as<br />
technology leaps forward, new<br />
devices may be employed such as<br />
camera based sensors and<br />
electromagnetic sensors. Due to the<br />
latter accuracy and speed it has<br />
been employed for this system.<br />
Robotics<br />
Operator directly controls 7DOF<br />
Cyton Gamma 1500 robotic arm.<br />
Due to 7DOF Cyton Gamma 1500<br />
robotic arm work like the human<br />
arm. Even if robots that have more<br />
than 6 six axis are called<br />
‘kinematically redundant', the extra<br />
degrees of freedom give fluid<br />
motion, better accuracy, and the<br />
ability to reach around obstacles<br />
making the use of its workspace to<br />
its fullest potential.<br />
However, due to the encoder errors<br />
that could not be calibrated<br />
correctly due to the hardware<br />
problems, robotic arm DOF has<br />
been reduced to 5.<br />
Due to the reduction of DOF<br />
workspace of the arm has been<br />
reduced drastically. On the other<br />
hand, robot inaccuracy has been<br />
reduced to minimum that allowed<br />
this tele-operation system possible.<br />
Implementation of the system<br />
Every component of the<br />
system has been connected<br />
using Robot Operating System<br />
(ROS) that ensured that the<br />
communication between<br />
different parts of the system<br />
works as intended.<br />
Furthermore, collaborative<br />
control has been implemented<br />
using “magnetic-field” idea –<br />
around every object there is<br />
an artificially created field. If<br />
manipulator end-effector<br />
enters specific object field, it<br />
will automatically align its endeffector<br />
to the object centroid<br />
position.<br />
Project summary<br />
This project was dedicated to improve current teleoperation<br />
systems as the current ones are bulky<br />
difficult to use. Collaborative control has been<br />
implemented in order to reduce operators cognitive<br />
workload and improve robot performance in<br />
achieving goals.<br />
Project Objectives<br />
Implement user-friendly tele-operation system that<br />
involves 3 different fields:<br />
1. Machine Vision<br />
2. Tracking<br />
3. Robotics<br />
Furthermore, improve robot and user performance<br />
by including collaborative control.<br />
Project Conclusion<br />
System has been successfully implemented and<br />
tested in a user study. Results from user study have<br />
shown that collaborative control has improved robot<br />
performance by reducing time to achieve goal (align<br />
robotic arm’s end-effector above desired object<br />
centroid position) and operators effort to achieve this<br />
task has been reduced.
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