Minimally Invasive Spinal Surgical Robot Velocity Control Method
Guoli Song
1,2
1
State Key Laboratory of Robotics
Shenyang Institute of Automation, Chinese Academy of
Science
Shenyang, China
2
University of Chinese Academy of Sciences,
Beijing, China
e-mail: songgl@sia.cn
Yiwen Zhao, Jianda Han, Zheng Wang, Huibin Du
Shenyang Institute of Automation, Chinese
Academy of Science
Shenyang, China
e-mail: zhaoyw@sia.cn; jdhan@sia.cn; wzheng@sia.cn;
duihuibin@sia.cn
Abstract—Vertebral pedicle screw placement is an important
part of spine surgery, surgreons hand screw placement
turnover rate was higher. With the development of surgical
robot and the robot navigation technology, robot surgery
applied in surgery became reality. Currently, the main purpose
of surgical robot is assisting the doctor to establish trajectory
of pedicle screw.
These could not exert the high performance of robot on
precision and speedy. Compared to conventional industrial
robots, the complexity and uncertainty in the surgical
environment and security needs of surgery will restrict the
robot to complete the operation automatically. This paper
establishes velocity field in operative space, completed the
simulation and experimental of surgical robot automatic
inserting pedicle screw. The simulation results show the
velocity field of the control algorithm advantages of minimally
invasive spine surgery procedure that can guarantee the
integrity of the contour under disturbance conditions and to
avoid damage to the nerve root.
Keywords-spine surgery; pedicle screw implantation; surgical
robot; velocity field control
I. INTRODUCTION
Vertebral pedicle screw fixation implant is an important
part of spine surgery, but failure rate of spinal pedicle screw
implant by surgeon manually is 3% to 55 %% [1-5]. Robots
instead of surgeon which have completed pedicle screws
implantation can improve the success rate [6-10]. At this
moment, the surgical robot applied in clinical is mostly
assisted positioning equipment, the main task of the robot is
establishing pedicle screw channel to assist surgeon
completing pedicle screw implantation procedure which do
not change basic stage of the surgery. For example,
SPINEASSIST surgical robot is mounted on the patient's
spine spinous process, and may be assisted surgical planning
and positioning device according to the moving position of
surgical planning, and ultimately surgeons completed pedicle
screw procedure [11]. ROSA spine [12] is another robot
which combines surgical robot and navigation system. With
an image-assisted surgery system, the surgical robot was
guided to surgical planning position, and ultimately assist
surgeon to complete pedicle screw. But fast and accurate
performance of robot could not be embodied during the
surgical process.
Currently, the robot can not completely replace a surge
onto complete spinal pedicle screw implantation mainly
because robots can not judge and handle the complex
environments which can reduce the accuracy of pedicle
screw placement even damage the spinal nerves. At the same
time, complexity and uncertainty of operation area could
bring greater interference. Compared to industrial robots,
based on the requirements of accuracy, surgical robots
should overcome a disturbance in a certain degree.
During the pedicle screw implanting process, the
changing of motor torque could cause the robot deviate from
the predetermined trajectory. It is crucial for robot to return
to the planned trajectory as soon as possible which could
avoid damage the nerves. Thus, the trajectory should be
adjusted to ensure accuracy, controllable and predictable. Li
proposed speed field control can solve these problems [13].
Different with traditional time and spatial mapping robot
trajectory planning, the velocity field is established planning
through velocity mapping and spatial position, which enables
surgical robot tracking planning contour precisely. Scholars
have verified the velocity control method not only ensures
the contour accuracy, but also to ensures the tracking contour
controllability, predictability [14-16]. Based on the theory of
velocity field, according to actual operation environment
robot path planning of surgery, and potential disturbances or
interference in surgical procedures, we proposed a surgical
robot control method, allowing the system to achieve high
trajectory accuracy.
II. PROBLEM DESCRIPTIOM
There are strict requirements on accuracy for implanting
pedicle screw trajectory as shown in Figure 1, the target
surgical robot trajectory is planned as the blue pedicle screw
in Figure 1.
Spinal nerve root is closed to the pedicle screws
implanted trajectory, the deviation of robot path will lead
injury to spinal nerve root which is unnecessary damage for
patient, even leading the patient paralysis.
Therefore, in the process of pedicle screws implanted,
robot path should ensure tracked and at the same time protect
the spinal nerve roots.
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2016 2nd International Conference on Control Science and Systems Engineering
978-1-4673-9870-1/16/$31.00 ©2016 IEEE