Kinematics-based Fault-tolerant Techniques: Lane Prediction for an Autonomous Lane Keeping System

International Journal of Control, Automation and Systems - In this paper, we propose the use of fault-tolerant techniques for an autonomous lane keeping system (LKS) under sensor failure of the...     

Predictive virtual lane method using relative motions between a vehicle and lanes

We propose a new approach for virtual lane prediction. The main contribution of the proposed method is that the predicted virtual lane can be substituted for lane detection using a camera sensor when the camera image processing fails to detect the lane. The proposed method generates the predicted virtual lane using the relative movement between a vehicle and a lane. To predict the lane, a third-order polynomial function of the longitudinal distance is used as a lane model. Each coefficient of the lane polynomial function at the next sampling time is geometrically calculated using the relative movement of a vehicle, the lanes, the longitudinal velocity and the yaw of the vehicle at the present time. Then, the predictive virtual lane at the next sampling time is obtained without the lane information from the camera sensor at the next sampling time. The proposed method is simple enough that it is suitable for real implementation. The performance of the proposed method was evaluated via experiments with a test vehicle.     

Adaptive digital demodulation of sinusoidal encoder signal for positioning control of spiral servo track writing

An adaptive digital demodulation method for a sinusoidal encoder signal is proposed for fast and accurate analysis of spiral servo track writing (SSTW). The proposed methods combine adaptive signal correction and digital interpolation. In addition, digital phase-shifted sinusoid (PSS) interpolation is proposed in order to acquire precise position information. The adaptive signal correction method compensates for a fast-motion non-ideal encoder signal. The digital PSS can be simply implemented and can resolve the switching noise of conventional analog methods. The proposed adaptive digital demodulation scheme can be simply digitalized and can improve the position control in SSTW. From the simulation and experimental results, we have validated the proposed methods, which show noticeable improvement in terms of the Lissajous error and the position error signal.     

Analysis of sliding mode proximate time-optimal disk drive servo control

An analysis of a sliding mode proximate time-optimal servomechanism (SPTOS) conducted through simulations and experiments is presented. The sliding mode is utilized to deliver proximate time-optimal performance naturally. We also examine why the SPTOS scheme is superior to the proximate time-optimal servomechanism that is widely used in the disk drive industry. The SPTOS is shown to produce bounded motion along the reference profile, which contributes to accurate reference profile tracking even in the presence of plant uncertainties. The application of the SPTOS yielded accurate reference velocity profile tracking as well as uniformly excellent seek performance regardless of the seek length.     

Active high-frequency vibration rejection in hard disk drives

This paper presents an active vibration rejection (AVR) control technique to reject actuator arm resonance modes using a piezoelectric sensor attached to the actuator arm to detect high-frequency off-track actuator vibration. The voice coil motor (VCM) is used as an actuator, while the piezoelectric sensor is used as a sensor only. A multirate digital implementation is proposed for high-frequency AVR over the sector-induced sampling frequency. The vibration control signal can be synchronized with the slow-state feedback control input such that the two control signals are summed and applied to the VCM. Throughout an application example the proposed AVR scheme, using the VCM as an actuator while the piezoelectric sensor as a sensor, is shown to be very prospective for high-frequency vibration rejection, provided a good vibration sensing scheme is used.