• Proceedings of the KIEE Conference
• /
• 2002.11d
• /
• pp.334-340
• /
• 2002

This paper proposes a new anti-slip re-adhesion control system fur electric railway vehicle driven by inverter-fed induction motors. This paper introduces an instantaneous tangential farce coefficient estimator between driving wheel and rail, which is based on disturbance observer. The torque command of proposed system regulates to exceed this estimated tangential farce coefficient in order to avoid undesirable slip phenomenon of driving wheels. We have already proposed the anti-slip re-adhesion control system based on disturbance observer for simplified one wheel equivalent model successfully. This paper extend to this system to the actual bogie system, which has four driving wheels driven by two induction motors fed by one inverter. In order to apply anti-slip re-adhesion control to the actual bogie system a new anti-slip re-adhesion control based on both disturbance observer and speed sensor-less vector control of induction motor with quick response are combined. The experimental results and the numerical simulation results prove the validity of the proposed control system.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.7
• /
• pp.713-717
• /
• 2014

In this paper, the travel control of the spherical wheeled robot with a mecanum wheel is impelemented. Four typical wheels or three omni wheels are used to consist of the ball-bot. the slip is occured when the typical wheels is used to the ball-bot. In order to reduce these slip, the spherical wheeled robot with macanum wheels is proposed. Through some experiments, we find that the proposed spherical wheeled robot with a mecanum wheel is superior to the conventional spherical wheeled robot with typical wheels.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.1
• /
• pp.58-69
• /
• 2014

This paper proposes a method for predicting maximum friction coefficients and optimal slip ratios as optimal control parameters for traction control or slip control of autonomous mobile robots on rough terrain. This paper focuses on strength of ground surface which indicates different characteristics depending on material types on surface. Strength of various material types can be estimated by Willoughby sinkage model and by a developed testbed which can measure forces, velocities, and displacements generated by wheel-terrain interaction. Estimated strength is collaborated on building improved Brixius model with friction-slip data from experiments with the testbed over sand and grass material. Improved Brixius model covers widespread material types in outdoor environments on predicting friction-slip characteristics depending on strength of ground surface. Thus, a prediction model for obtaining optimal control parameters is derived by partial differentiation of the improved Brixius model with respect to slip. This prediction model can be applied to autonomous mobile robots and finally gives secure maneuverability on rough terrain. Proposed method is verified by various experiments under similar conditions with the ones for real outdoor robots.

• International Journal of Automotive Technology
• /
• v.3 no.4
• /
• pp.165-170
• /
• 2002

For a vehicle Anti-lock Braking System (ABS), the control target is to maintain friction coefficients within maximum range to ensure minimum stopping distance and vehicle stability. But in order to achieve a directionally stable maneuver, tire side forces must be considered along with the braking friction. Focusing on combined braking and turning operation conditions, this paper presents a new control scheme for an ABS controller design, which calculates optimal target wheel slip ratio on-line based on vehicle dynamic states and prevailing road condition. A fuzzy logic approach is applied to maintain the optimal target slip ratio so that the best compromise between braking deceleration, stopping distance and direction stability performances can be obtained for the vehicle. The scheme is implemented using an 8-DOF nonlinear vehicle model and simulation tests were carried out in different conditions. The simulation results show that the proposed scheme is robust and effective. Compared with a fixed-slip ratio scheme, the stopping distance can be decreased with satisfactory directional control performance meanwhile.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.626-631
• /
• 2004

In electric motor coaches, the rolling stocks move by the adhesive effort between rail and driving wheel. Generally, the adhesive effort is defined by the function of both the weight of electric motor coach and the adhesive effort between rails and driving wheel. The characteristics of adhesive effort is strongly affected by the conditions between rails and driving wheel. When the adhesive effort decreases suddenly, the electric motor coach has slip phenomena. This paper proposes a re-adhesion control algorithm which uses the maximum adhesive effort by instantaneous estimation of adhesion force using load torque disturbance observer. Based on this estimated adhesive effort, the re-adhesion control is performed to obtain the maximum transfer of the tractive effort.

• Journal of Auto-vehicle Safety Association
• /
• v.13 no.3
• /
• pp.6-12
• /
• 2021

This paper presents a lateral stability control for rear wheel drive (RWD) vehicles using electronic limited slip differentials (eLSD). The proposed eLSD controller is designed to increase the understeer characteristic by transferring torque from the outside to inside wheel. The proposed algorithm is devised to improve the lateral responses at the steady state and transient cornering. In the steady state response, the proposed algorithm can extend the region of linear cornering response and can increase the maximum limit of available lateral acceleration. In the transient response, the proposed controller can reduce the yaw rate overshoot by increasing the understeer characteristic. The proposed algorithm has been investigated via computer simulations. In the simulation results, the performance of the proposed controller is compared with uncontrolled cases. The simulation results show that the proposed algorithm can improve the vehicle lateral stability and handling performance.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.10
• /
• pp.1062-1072
• /
• 2008

When mobile robots perform the mission in the rough terrain, the traversability depended on the terrain characteristic is useful information. In the traversabilities, wheel-terrain maximum friction coefficient can indicate the index to control wheel-terrain traction force or whether mobile robots to go or not. This paper proposes estimating wheel-terrain maximum friction coefficient. The existing method to estimate the maximum friction coefficient is limited in flat terrain or relatively easy driving knowing wheel absolute velocity. But this algorithm is applicable in rough terrain where a lot of slip occurred not knowing wheel absolute velocity. This algorithm applies the tire-friction model to each wheel to express the behavior of wheel friction and classifies slip-friction characteristic into 3 major cases. In each case, the specific algorithm to estimate the maximum friction coefficient is applied. To test the proposed algorithm's feasibility, test bed(ROBHAZ-6WHEEL) simulations are performed. And then the experiment to estimate the maximum friction coefficient of the test bed is performed. To compare the estimated value with the real, we measure the real maximum friction coefficient. As a result of the experiment, the proposed algorithm has high accuracy in estimating the maximum friction coefficient.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.6
• /
• pp.40-48
• /
• 2013

Recently, many types of electric vehicles including a heavy duty vehicle have been developed and released because of the better fuel economy and less gas products. In this study, research about an electric bus which utilizes the wheel motor drive system was conducted. The wheel motor is a motor connected to the wheel directly only with a simple gear so that the developer can utilize the space efficiently and the whole system efficiency will be better because of simple structure. However, because it is different from former types of vehicles which use the differential gear, the development of the integrated control logic is required in order to meet the vehicle stability and driving performance. The developed control logic is composed with direct yaw moment control, regenerative braking control and slip control logics. It is compared to the control logics which does not consist of direct yaw moment control and slip control when the vehicle is exposed in tough situations. For the unification of the control logic, a few maps were developed and applied to determine the output torque of each motor according to the driving status. As a result, it is shown that the developed control logic is more safe and well follow the target speed than the other control logic applied simulations.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.2
• /
• pp.139-147
• /
• 2004

The purpose of engine control TCS is to regulate engine torque to keep driven wheel slip in a desired range. In this paper, engine control TCS using sliding mode control law based on engine model and estimated load torque is proposed. This system includes a two-level controller. Slip controller calculates desired wheel torque, and engine torque controller determines throttle angle for engine torque corresponding to desired wheel torque. Another issue is to measure load torque for model based controller design. Luenberger observer with state variables of load torque and engine speed solves this problem as estimating load torque. The performance of controller and observer is certificated by simulation using 8-degree vehicle model, Pacejka tire model, and 2-state engine model. The simulation results in various maneuvers during slippery and split road conditions showed that acceleration performance and ability of the vehicle with TCS is improved. Also, the load torque observer could estimate real load torque very well, so its performance was proved.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.420-422
• /
• 1999

To improve traction effort performance and stability of Korean High-Speed Railway Train, a practical re-adhesion controller including a novel wheel slip protection control scheme is proposed. The presented method is verified by various train running simulations by induction motor vector control with PWM inverter.