• The Journal of Korea Robotics Society
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• v.5 no.4
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• pp.286-293
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• 2010

The trailer system offers efficiency of transportation capability. However, it is difficult to control the backward motion. It is an open loop unstable problem. To solve this problem, we are proposed the driver assistance system. Driver assistance system assists a driver to control the backward motion of trailer system as if forward motion. A driver only secure the rear view of last passive trailer, and select the control input to drive the last passive trailer. The driver assistance system converts the control input of the driver into velocity and steering angle of the vehicle using the inverse kinematics. It is possible by electronic control input devices and the rear view camera. Effectiveness of driving assistance system is verified by the simulation and the experiments.

• The Journal of Korea Robotics Society
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• v.4 no.4
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• pp.273-280
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• 2009

It is difficult to find a practical solution for the backward-motion control of a car-like mobile robot with n passive trailers. Unlike an omni-directional robot, a car-like mobile robot has nonholonomic constraints and limitations of the steering angle. For these reasons, the backward motion control problem of a car-like mobile robot with $n$ passive trailers is not trivial. In spite of difficulties, backing up a trailer system is useful for parking control. In this study, we proposed a mechanical alteration which is connecting $n$ passive trailers to the front bumper of a car to improve the backward motion control performance. Theoretical verification and simulations show that the backward-motion control of a general car with n passive trailers can be successfully carried out by using the proposed approach.

• Journal of the Korean Institute of Navigation
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• v.18 no.4
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• pp.11-21
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• 1994

Final aim of this paper is a study on simulation of automatic steering of a ship in random seas. In order to achieve this aim, we need excitation due to random seas. The excitation may be estimated from energy spectrum of irregular waves and response functions of manoeuvring motion of a ship in regular waves. This paper deals with response functions of manoeuvring motion of a ship in regular waves. We discussed New Strip Method(NSM) of sway-yaw-roll coupled motions in regular waves. NSM is defined in space axes system and that has been used to predict seakeeping performance of a ship in waves. But ship manoeuvring is defined in body fixed axes system. So we cannot use NSM theory itself in predicting manoeuvring performance of a ship in waves. We introduced relationship between space axes system and body fixed axes system. And we developed modified NSM which was defined in body fixed axes system and was able to be used in manoeuvring motion of a ship in waves. We calculated sway and yaw response functions of manoeuvring motion of a bulk carrier in regular waves.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.331-332
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• 2012

• Journal of the Ergonomics Society of Korea
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• v.35 no.1
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• pp.11-27
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• 2016

Objective: The purpose of this study was to develop and evaluate high technology adaptive driving controls, such as mini steering wheel-lever system and joystick system, for the people with physical disabilities in the driving simulator. Background: The drivers with severe physical disabilities have problems in operation of the motor vehicle because of reduced muscle strength and limited range of motion. Therefore, if the remote control system with driver-by-wire technology is used for adaptive driving controls for people with physical limitations, the disabled people can improve their quality of life by driving a motor vehicle. Method: We developed the remotely controlled driving simulator with drive-by-wire technology, e.g., mini steering wheel-lever system and joystick system, in order to evaluate driving performance in a safe environment for people with severe physical disabilities. STISim Drive 3 software was used for driving test and the customized Labview program was used in order to control the servomotors and the adaptive driving devices. Thirty subjects participated in the study to evaluate driving performance associated with three different driving controls: conventional driving control, mini steering wheel-lever controls and joystick controls. We analyzed the driving performance in three different courses: straight lane course for acceleration and braking performance, a curved course for steering performance, and intersections for coupled performance. Results: The mini steering wheel-lever system and joystick system developed in this study showed no significant statistical difference (p>0.05) compared to the conventional driving system in the acceleration performance (specified speed travel time, average speed when passing on the right), steering performance (lane departure at the slow curved road, high-speed curved road and the intersection), and braking performance (brake reaction time). However, conventional driving system showed significant statistical difference (p<0.05) compared to the mini steering wheel-lever system or joystick system in the heading angle of the vehicle at the completion point of intersection and the passing speed of the vehicle at left turning. Characteristics of the subjects were found to give a significant effect (p<0.05) on the driving performance, except for the braking reaction time (p>0.05). The subjects with physical disabilities showed a tendency of relatively slow acceleration (p<0.05) at the straight lane course and intersection. The steering performance and braking performance were confirmed that there was no statistically significant difference (p>0.05) according to the characteristics of the subjects. Conclusion: The driving performance with mini steering wheel-lever system and joystick control system showed no significant statistical difference compared to conventional system in the driving simulator. Application: This study can be used to design primary controls with driver-by-wire technology for adaptive vehicle and to improve their community mobility for people with severe physical disabilities.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.324-327
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• 1996

This paper describes the robust controller design methods applied to the problem of an automatic system for tow-vehicle/trailer combinations. This study followed an inverse Linear Quadratic Regulator(LQR) approach which combines pole assignment methods with conventional LOR methods. It overcomes two concerns associated with these separate methods. It overcomes the robustness problems associated with pole placement methods and trial and error required in the application of the LQR problem. Moreover, a Kalman filter is used as the observer, but is modified by using the loop transfer recovery (LTR) technique with modified transmission zero assignment. The proposed inverse LQG,/LTR controllers enhances the forward motion stability and maneuverability of the combination vehicles. At high speeds, where the inherent yaw damping of the vehicle system decreases, the controller operates to maintain an adequate level of yaw damping. At backward moton, both 4WS (2WS tow-vehicle, 2WS trailer) and 6WS (4WS tow-vehicle, 2WS trailer) control laws are proposed by using inverse LQG/LTR method. To evaluate the stability and robustness of the proposed controllers, simulations for both forward and backward motion were conducted using a detailed nonlinear model. The proposed controllers are significantly more robust than the previous controllers and continues to operate effectively in spite of parameter perturbations that would cause previous controllers to enters limit cycles or to loose stability.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.120-127
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• 2007

This paper describes the development of a nonlinear observer for four wheel steer (4WS) vehicle. An observer is designed to estimate the vehicle variables difficult to measure directly. A brake yaw motion controller (BYMC), which uses a PID control method, is also proposed for controlling the brake pressure of the rear and inner wheels to enhance lateral stability. It induces the yaw rate to track the reference yaw rate, and it reduces a slip angle on a slippery road. The braking and steering performances of the anti-lock brake system (ABS) and BYMC are evaluated for various driving conditions, including straight, J-turn, and sinusoidal maneuvers. The simulation results show that developed ABS reduces the stopping distance and increases the longitudinal stability. The observer estimates velocity, slip angle, and yaw rate of 4WS vehicle very well. The results also reveal that the BYMC improves vehicle lateral stability and controllability when various steering inputs are applied.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.6
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• pp.721-728
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• 2012

The tracked SUGVs(Small Unmanned Ground Vehicles) are frequently operated in the narrow slope such as stairs and trails. But due to the nature of the tracked vehicle which is steered using friction between the track and the ground and the limited field of view of driving cameras mounted on the lower position, it is not easy for SUGVs to trace narrow slopes. To properly trace inclined narrows, it is very important for SUGVs to keep it's heading direction to the slope. As a matter of factor, no roll value control of a SUGV can makes it's heading being located in the direction of the slope in general terrains. But, the problem is that we cannot directly control roll motion for SUGV. Instead we can control yaw motion. In this paper, a new slope driving method that enables the vehicle trace the narrow slopes with IMU sensor usually mounted in the SUGV is suggested which including an estimation technique of the desired yaw angle corresponding to zero roll angle. In addition, a fuzzy steering controller robust to changes in driving speed and the stair geometry is designed to simulate narrow slope driving with the suggested method. It is shown that the suggested method is quite effective through the simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2066-2071
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• 2003

In this paper, we identify the isotropic configurations of an omnidirectional mobile robot with three caster wheels, depending on the selection of actuated joints. First, We obtain the kinematic model of a caster wheeled omnidirectional mobile robot(COMR) without matrix inversion. For a given task velocity, the instantaneous motion of each wheel is decomposed into two orthogonal instantaneous motions of the steering and the rotating joints. Second, with the characteristic length introduced, we derive the isotropy conditions of a COMR having $n({\ge}3)$ actuated joints, which are imposed on two Jacobian matrices, $A{\in}R^{n{\times}3}$ and $B{\in}R^{6{\times}6}$. Under the condition of $B{\propto}I_6$, three caster wheels should have identical structure with the length of the steering link equal to the radius of the wheel. Third, depending on the selection of actuated joints, we derive the conditions for $A^t$ $A{\propto}I_3$ and identify the isotropic configurations of a COMR. All possible actuation sets with different number of actuated joints and different combination of rotating and steering joins are considered.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.615-623
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• 2005

In this research, an effective technique was examined to improve the drift running performance. Concretely, the driver model by which the counter steer was done was assumed to the model by which the vehicle body slip angle (and the vehicle body slip angle velocity) was feed back. Next, the effectiveness of the system which added the assist steer angle corresponding to the steering wheel angle velocity to a front wheel steer angle was clarified as a drift running performance improvement technique of the vehicle. As a result, because the phase advances when the differentiation steer assistance is added, it has been understood to be able to cover the delay of the counter steer when the drift running. Therefore, it has been understood that the drift control does considerably easily. Moreover, it has been understood that the differentiation steer assistance acts effectively at the drift cornering by which the drift angle is maintained in cornering and the severe lane change with a drift at a situation. That is, it was understood to be able to settle to the drift angle of the aim quickly at the time of the drift cornering because the delay of the control steer angle of the counter steer was improved. Moreover, it was understood for the transient overshoot of the vehicle tracks to be able to decrease, and to return to the state of stability quickly at the severe lane change.