Seongil Hong

Kinematic Algorithms and Robust Controller Design for Inertially Stabilized System

This paper describes a controller design method for the inertially stabilized system of a tracking radar. Its aim is to track a reference target trajectory with high accuracy while isolating rigid body rotational motions of a host ship. First, we investigate the trajectory generation problem to make the control input for a target tracking on the moving base. Second, dynamic equations of motion are formulated by the spring-mass-damper system to include rigid body dynamics as well as structural flexibility. The unknown parameters of dynamic equations are estimated with experimental input and output data by minimizing a predicted error. Third, mixed sensitivity H∞ robust controllers are designed to meet the conflict requirements of robustness and performance in the face of uncertainty. Finally, the proposed optimal controllers demonstrate the effectiveness of design methodology, and show high performance by numerical and experimental results.

A whole-body rescue motion control with task-priority strategy for a rescue robot

This paper introduces a new rescue robot consisting of dual-manipulator and variable configuration mobile platform for multi-purpose such as casualty extraction and hazardous goods transport. A specific rescue motion strategy using a whole-body is suggested to tackle characteristics of the robot configuration and balancing issue. In order to take into account safety and stability of the robot during the rescue motions, some restrictions are reflected into redundant domain of the robot with different priority. For stable motion control in various scenarios, a singularity-robust inverse kinematics is adopted and modified to induce smoother robot movement. The robustness of the control approach is checked numerically by comparing other method and experiments for the rescue motion strategy are carried out by using a small-scaled simulator in place of the rescue robot under development.

Dynamics based motion optimization and operational space control with an experimental rescue robot, HUBO T-100

This paper introduces an experimental rescue robot, HUBO T-100 for a development of a Korean rescue robot with a large load carrying capacity and presents its optimal motion control methods. The mission of the rescue robot is to move and lift patients or soldiers with impaired mobility for the rescue and assistance in the battlefields, hospitals, hazardous and disastrous environments. Another mission includes to dispose and transfer a dangerous object or explosive ordnance. In order to execute these kind of missions, coordinated whole body motions need to be synthesized. We are to make use of a dynamics based motion optimization in the joint space to lift a object with the minimum joint torques while maintaining stability simultaneously. Complex tasks are planned in the operational space and controlled in the multi level hierarchy based on a task primitive priority. Experimental results are to be demonstrated, both in simulations and physical experiments with a humanoid robot, HUBO T-100.

Self-Collision Detection/Avoidance for a Rescue Robot by Modified Skeleton Algorithm

This paper handles self-collision avoidance for a rescue robot with redundant manipulators. In order to detect all available self-collisions in advance, minimum distances between arbitrary robot parts should be monitored in real-time. For the minimum distance estimation, we suggest a modified method from a previous skeleton algorithm which has less computation burden and realize collision avoidance based on a potential function using the proposed algorithm. The resultant command by collision avoidance should not disturb a given primary task, so null-space of joint solution from a CLIK is utilized for collision avoidance by a gradient projection method.

Whole-body motion control for a rescue robot using robust task-priority based CLIK

This paper introduces a rescue robot to extract a casualty from hazardous environment and suggests a specific whole-body behavior strategy suitable for the rescue mission taking into account the characteristics of the robot configuration. Since the robot has redundant degrees of freedom, a task-priority based CLIK as differential inverse kinematics approach is adopted for real-time implementation and the redundant domain is utilized to reflect some restrictions in terms of safety and stability of the robot. When multiple tasks with different priority are handled simultaneously by the CLIK, a well-known Algorithmic Singularity problem could be taken place. For this issue, hence, this study applies a robust algorithm against the algorithmic singularity as well as the kinematic singularity and its applicability is verified through a real experiment using a small-scaled simulator instead of the developing rescue-robot.

Development of an Experimental Humanoid Robot and Dynamics Based Motion Optimization for Rescue Missions

This paper introduces an experimental rescue robot, HUBO T-100 and presents the optimal motion control method. The objective of the rescue robot is to extract patients or wounded soldiers in the battlefield and hazardous environments. Another mission is to dispose and transport an explosive ordnance to safe places. To execute these missions, the upper body of the rescue robot is humanoid in form to execute various kinds of tasks. The lower body features a hybrid tracked/legged design, which allows for a variety of mode of locomotion, depending on terrain conditions in order to increase traversability. The weight lifting motion is one of the most important task for performing rescue related missions because the robot must lift an object or impaired person lying on the ground for transferring. Here, dynamics based motion optimization is employed to minimize joint torques while maintaining stability simultaneously. Physical experiments with a real humanoid robot, HUBO T-100, are presented to verify the proposed method.

Kinematic Control Algorithms and Robust Controller Design for Rescue Robot

This paper introduces the Korean rescue robot and presents the kinematic and dynamic control method. The mission of the rescue robot is to move and lift patients or soldiers with impaired mobility for the rescue and assistance in the battlefields, hospitals, hazardous and disastrous environments. In order for robots to rescue and assist humans in various environments, reliable mobility and dextrous manipulability are required. For these objects the robot has variable configuration mobile platform with tracks, dual arm manipulators and two types of grippers. The electric actuators provide manipulator compliance and the strength to lift wounded soldiers up to 120kg by virtue of whole body joints. For controlling the robots high degree of freedom efficiently, complex whole body behaviors are synthesized and multi level hierarchy is used to integrate multiple task primitives without confliction. Moreover, the robot should have an ability to cope with large payload variation from 0kg to 120kg, robust PID controllers are utilized. They afford extended disturbance input to state stability, H∞ performance and controller tuning laws. We are to demonstrate the effectiveness of kinematic control algorithms and robust PID controllers through numerical simulations.

Trajectory generation and ℋ ∞ robust control for inertially stabilized system

This paper describes a controller design method for inertially stabilized system of tracking radar. Its aim is to track a reference target trajectory while isolating any rigid body motion of a host ship. First, we treat the trajectory generation problem to make the control input for a target tracking on the moving base. Second, dynamic equation of motion is formulated by spring-mass-damper system to include rigid body dynamics as well as structural flexibility. The unknown parameters of the dynamic equation are estimated with experimental input output data by minimizing predicted error. Third, mixed sensitivity ℋ∞ robust controller is designed to meet the conflict requirements of robustness and performance in the face of plant uncertainty. Finally, the proposed optimal controller is implemented and show the effectiveness of design methodology by experimental results.