This paper proposed a CNC interpolator based on block overlap, capable of changing acceleration and deceleration time constants during continuous machining. The time constant can be set individually for each block through G-code commands. A velocity profile generation algorithm is proposed to set different time constants for both acceleration and deceleration phases. This algorithm can be applied to short blocks. The block overlap algorithm can be used for corner smoothing. A simulation model of the CNC interpolator was constructed to evaluate the proposed interpolation algorithm. Simulation results demonstrated that the proposed algorithm increased precision in areas with significant angular changes by adjusting time constants while simultaneously reducing machining time.

Automated valet parking systems have been researched because they provide a good service condition for autonomous vehicles, with their limited space and unmanned environment. Previous parking algorithms focused on planning a path to a parking space based on geometry. However, this approach only works when the parking space is simple. To make automated parking algorithms useful in different environments, it is crucial to drive a path from the entrance to the target space and plan a safe parking path, taking into account the surrounding vehicles in the parking lot. This study organizes the structure of the automated valet parking system into two phases. The first phase involves driving from the origin to the destination. The second phase focuses on planning a path for parking the vehicle in the parking lot. It considers the position, orientation, and parking space to plan a path that aligns correctly. Simulation results demonstrate that the proposed algorithm can plan paths in various parking environments and park vehicles in narrow parking spaces. It is expected that this proposed automated valet parking algorithm can be further improved to contribute to the early commercialization of automated driving technology.

The kinematic constraints used in a computerized numerical control (CNC) interpolator are one of the main factors determining a machine tool’s machining accuracy. The CNC generates velocity profiles by applying kinematic constraints such as jerk and acceleration. Therefore, changing the kinematic constraints values can adjust the cycle time and cornering error. This study proposes a method to adjust the kinematic constraint values. First, the relationship between CNC kinematic constraints and cornering errors were analyzed. The relationship between the kinematic constraints and the cornering error was expressed as an analytical solution. Kinematic constraint values that satisfy specific cornering error values were selected using the analytical solution of cornering error. Finally, a method was devised to apply the appropriate kinematic constraint values to each machining section within a part program. The analytical solutions for cornering errors and using different machining segments to control cornering errors were verified using tool path generation simulation.

This paper proposes a cycle time estimation algorithm of a CNC machine tool, using a block overlap based tool path generation algorithm. Velocity profile generation algorithm of CNC interpolator is proposed to compute the cycle time of the G-Code block. Because the CNC blends adjacent velocity profiles to reduce the cycle time and smooth the tool path, the cycle time is adjusted considering the block overlap. The in-position time of rapid traverse is compensated to improve the cycle time estimation accuracy. The simulation model was designed to estimate the cycle time of the CNC machine tool. A three-axis feed drive testbed was used to evaluate the cycle time estimation accuracy of the proposed algorithm.

In CNC machining, NC data created by CAM software is usually linearly interpolated. This linearly interpolated tool path, however, may degrade the dynamic motion performance of the machine tool and the geometric accuracy in comparison with the reference CAD data. Tool path smoothing can be an effective way to address these problems. In this paper, a five-axis tool path smoothing method is proposed based on dual cubic B-spline curves. The proposed smoothing method includes two steps. First, the tool orientation is adjusted to reduce drastic changes in tool orientation movement. Then, dual B-spline curves are generated for smooth interpolation of tool position and orientation, wherein their control points are created by using modified internal division points between the top and bottom points of the tool defined by given tool position and orientation vectors. The B-spline curves pass through the junctions of straight line segments comprising the top and bottom points, respectively. Smooth tool position and orientation vectors are finally obtained by simultaneous interpolation of the B-spline curves. The proposed method is implemented in a PC-based five-axis control system and experimentally demonstrated to show improvements in the dynamic motion performance and the geometric accuracy compared with the conventional linear interpolation.

This paper presents a GPS-based method for outdoor robots to track humans. This new method can overcome the crucial problems of conventional techniques in complex environments with obstacles or sloped terrain that do not allow detecting the locations of humans out of the robot"s line of sight. The robot determines the position of the human with respect to GPS data and forms the trajectory of the human’s movement. This trajectory is then smoothed in real time to reduce sudden changes in the path and improve the tracking performance. We also propose an autonomous trajectory tracking method for the robot to avoid obstacles while effectively tracking the human trajectories. This method allows the robot to follow the human even in an environment with many robots and humans simultaneously present because the robot can always distinguish the human it should follow. The experiments demonstrate that robots can effectively follow the human while avoiding obstacles in complex environments.