A Computer-Assisted Preoperative Path Planning Method for the Parallel Orthopedic Robot

Abstract

Background: Trajectory planning is the premise of the control of orthopedic robots, which is directly related to the safety of the human body. However, to date, the trajectory of orthopedic robots has been restricted to lines and spline curves. This limits the flexibility of the robot and leads to unsatisfactory performance. In this paper, a trajectory planning method based on improved RRT* and B-spline curve is proposed in order to improve the control accuracy and flexibility. Method: Firstly, combined with the shortcomings of current trajectory planning methods and bone docking task analysis, the characteristics of the trajectory for orthopedic robot are illustrated, and the problem is described. Secondly, a sampling strategy and an extension strategy are proposed to solve the optimal problem of the RRT* algorithm. Meanwhile, B-spline curve is selected for path smoothing. Thirdly, based on our orthopedic robot, kinematics analysis is introduced briefly, and hypotonic polynomial is used to fit the joint variables. Finally, a comparative study of the improved RRT*, RRT*, and other algorithms are completed, and the feasibility of the robot’s trajectory is verified by algorithm simulation and platform simulation. Results: Compared with RRT*, shorter path and high node utilization are shown in the improved RRT*, which cut down about 1mm in the average path length and increased about half in the average node utilization. In the meantime, the fitting results are accepted, and the results of algorithm simulation and platform simulation showed good consistency and feasibility. Conclusions: This study revealed that the improved RRT* was superior to RRT*, and the proposed method could be used for the trajectory planning of parallel orthopedic robots, which has some significance for bone fracture and deformity correction.

Technologies evolution in robot-assisted fracture reduction systems: a comprehensive review

“…Researchers have increasingly focused on automatically reducing path planning in recent years, with most studies concentrating on path search methods. Whether manual, semiautomatic, or automatic methods, such as the A* or RRT* algorithm (Li et al, 2022), are used, the primary goal is to find the shortest path while avoiding collisions. However, fracture reduction is a complex problem involving the surrounding soft tissues, which induces resistance during the reduction procedure.…”

Autonomous path planning for robot‐assisted pelvic fracture closed reduction with collision avoidance

“…Recently, Li et al 15 . presented the rapidly exploring random tree algorithm (RRT*) to search the path of the RLFCR.…”

“…The ray‐cast method is no longer applicable in the pelvic environment. Li 15 utilised cylindrical and spherical bounding boxes to detect collisions between bones, which only applies to simple bone morphology. In addition, Xu 18 proposed a discrete intersection test, which identifies whether the point cloud data of distal and proximal fragments intersect to determine whether a collision exists.…”

“…Recently, Li et al 15 presented the rapidly exploring random tree algorithm (RRT*) to search the path of the RLFCR. Due to the random nature of the RRT* algorithm, it resulted in low search efficiency.…”