Zhang
etal. Robot. Biomim. (2018) 5:3
https://doi.org/10.1186/s40638-018-0085-7
RESEARCH
A 6-DOF robot-time optimal trajectory
planning based onanimproved genetic
algorithm
Jiayan Zhang, Qingxi Meng
*
, Xugang Feng and Hao Shen
Abstract
By using quintic polynomial function to interpolate several given points of each joint of the robot, the mathematical
expressions of each joint variable of the robot with time are established. In addition, to improve the search algo-
rithm performance crossover operator and mutation operator of the genetic algorithm are improved in cosine form.
Furthermore, the improved adaptive genetic algorithm is applied to optimize the time interval of interpolation points
of each joint, so as to realize time optimal trajectory planning. Moreover, MATLAB simulation is carried out, and the
results show that the method proposed in this paper reduces the running time of the robot tasks. Meanwhile, the
curves of angle position, velocity and acceleration of each joint are smooth enough, which ensure accomplish its
tasks in a stable and efficient way.
Keywords: Industrial robot, Trajectory planning, Adaptive genetic algorithm (AGA), Time optimal
© The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License
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and indicate if changes were made.
Background
Robot trajectory planning usually refers to track points
given several expectations and target pose, and timely
adjust the rotation angle of each joint of the robot to the
end effector at a prescribed trajectory followed by each
point to eventually reach the target point. e trajectory
planning in joint space is simpler and convenient than
that of Cartesian space. erefore, several fixed points
which located at the end of several robotic arms are usu
-
ally given. en, these track points for the robot are com-
puted by using the inverse kinematics so as to convert it
from Cartesian space to joint coordinate space. Next, the
track points are used to carry out interpolation opera
-
tion using various spline functions, polynomial functions
or other forms of curves, and the expressions about the
time of each joint variable for the robot are obtained. In
addition, in light of the mechanical characteristics of the
robot, the speed and acceleration of each joint should be
limited to the allowable range. erefore, it is necessary
to optimize the speed and acceleration of each joint arm,
not only to ensure the smooth operation of the joint arm
but also to reduce the wear and impact to prolong the
working life of the robot.
e method of optimal trajectory planning generally
includes time optimal trajectory planning [1–3], energy
minimum trajectory planning [3, 4] and impact mini
-
mum trajectory planning [5], or multi-objective trajec-
tory optimization combining these estimation schemes.
Among them, the optimal trajectory planning with the
robot running time as main consideration is favored by
many scholars. In recent years, many researchers have
made some achievements in the field of robot trajectory
planning. Tohfeh and Fakharian [6] constructed a func
-
tion expression for the omnidirectional robot’s energy
dissipation by combining obstacle avoidance perfor
-
mance, and the optimization problem was transformed
into a parameter minimization problem by the poly
-
nomial interpolation method, which provided a more
effective way for the study of robot obstacle avoidance.
However, due to the complexity of this method, there is a
certain degree of difficulty in practice. Bende [7] studied
a method of modeling underwater robot based on bond
graph theory and optimized the model parameters with
the genetic algorithm to obtain the optimized trajectory
Open Access
*Correspondence: mqx3021@qq.com
College of Electrical Engineering and Information, Anhui University
of Technology, Ma’anshan 243002, China