In this study, polyacetal plates were machined with an indexable drill (Ø18mm) to measure the dimensional error of holes according to the cutting conditions and investigate the influencing factors to obtain precision holes. Cutting velocity, feed, and depth of cut were selected as experimental variables, analyzed using design of experiment, and optimal cutting conditions were investigated. Cutting velocity and feed were significant factors affecting hole accuracy, whereas depth of cut had little effect. The factor with the greatest influence on hole accuracy was cutting velocity, and the dimensional error of the holes tended to increase as the cutting velocity increased. Dimensional error tended to decrease as feed increased. In addition, the interaction effect between cutting velocity and feed and cutting velocity and depth of cut were significant. In this experiment, the optimal cutting velocity, feed, and depth of cut needed to minimize the dimensional error of holes were 100 m/min, 0.15 mm/rev, and 2 mm, respectively.

As advanced driver-assistance systems become more common in commercial vehicles, there is a growing need for evaluating safety of vehicles. Low platform target robot systems play a crucial role in this evaluation process as they can assess safety performances of autonomous vehicles. Driving stability of a target robot during real vehicle tests depends significantly on its suspension system. Therefore, developing an appropriate suspension device for the target robot is of utmost importance. This study aimed to improve driving stability by comparing two different suspension configurations: a single rocker and a double rocker, both incorporating a crank rocker mechanism. Initially, a two-dimensional model that met constraints of the suspension device was developed, followed by an analysis of reaction forces. Subsequently, an optimal design was determined using design of experiments principles based on parameters of a 2D model. The manufactured suspension system model based on the optimal design underwent multi-body dynamics simulation to evaluate driving stability. Comparative analysis of driving stability for both configurations was performed using MBD simulation, offering insights into the superior suspension design for the target robot.