Servo controller design and fault detection algorithm for speed control of conveyor system

This paper proposes a servo controller design and fault detection algorithm for speed control of conveyor system (CS). Firstly, modeling for a CS is described. Secondly, the robust servo controller based on polynomial differential operator is applied to track the trapezoidal velocity profile reference input. Thirdly, a fault detection algorithm based on Extended Kalman Filter (EKF) is proposed.
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Servo controller design and fault detection algorithm for speed control of conveyor system SERVO CONTROLLER DESIGN AND FAULT DETECTION ALGORITHM FOR SPEED CONTROL OF CONVEYOR SYSTEM Nguyen Trong Hai HUTECH Institute of Engineering, Ho Chi Minh City University of Technology (HUTECH)ABSTRACTThis paper proposes a servo controller design and fault detection algorithm for speed control of conveyorsystem (CS). Firstly, modeling for a CS is described. Secondly, the robust servo controller based onpolynomial differential operator is applied to track the trapezoidal velocity profile reference input.Thirdly, a fault detection algorithm based on Extended Kalman Filter (EKF) is proposed. From the EKF,the estimated angular velocity indicates the encoder failure. The estimated friction indicates themechanical failure Fault isolation is obtained by the friction bound. Finally, the simulation andexperimental results are shown to verify the effectiveness of the proposed algorithm.Keywords: Fault detection, Internal model principle, Kalman Filter, Servo system, Speed control.1. INTRODUCTIONConveyors are material handling devices not only to transport loads/units but also to sort or store themtemporarily. Most AC motor drives have used PI control [1] but difficult for applying to obtainsufficiently high performance in the tracking application. To satisfy the tracking requirements, hugeamount of algorithms were proposed by researchers [2]–[5]. However, the transient performances arealways unsatisfactory. To solve this problem, Kim, S. B. et al. [6-7] proposed a new concept of servocontroller design method by introducing a polynomial differential operator. In this paper, a robust servocontroller proposed by Kim, S. B. et al [7] is applied for speed control of a CS. The experimental results ofthe proposed servo controller are compared to the conventional PI controller and MRAC controller.Since the CS work automatically, their safety is considered. In order to maintain the conveyor system,several features such as energy consumption, output, temperature, vibrations, belt speed etc. might bemonitor. The fault detection algorithm helps user to detect faults and prevents serious damage in theconveyor. Therefore, many fault detection algorithms were proposed to increase the safety and reliabilityof conveyor system [8-10]. Li, X. G. et al. [8] proposed the fault detection algorithm named ModifiedRegular Bands based on X-ray image to monitor the status of steel cord conveyor belt. Jiang, X. P. et al.[9] proposed a belt conveyor roller fault audio detection based on the wavelet neural network. Kanmani,M. [10] proposed faults such as belt tear up faults, oil level reduction fault, fire occurrence fault by usingPLC and SCADA. However, this method had high computational cost. Therefore, to deal with theseproblems, this paper proposes an improved fault detection algorithm for the CS with known mathematicalmodel and low computational cost. In this paper, a fault detection algorithm based on EKF is proposed.From the EKF, the estimated angular velocity indicates the encoder failure. The estimated frictionindicates the mechanical failure Fault isolation is obtained by the friction bound.2. SERVO CONTROLLER DESIGNThe state dynamic equation of a given system with disturbance  can be expressed as follows:1498  x  Ax  Bu    (1)  y  vL  Cx  0 1  0 where A    , B    , C   Rb 0 , a1   bL J L  , a2   Rb2 K J L  , b1   Ra Rb K J L  ,  a2 a1  b1  x   x1 x2   L L  , u  m , vL  RbL T Twhere vL is the belt linear velocity, K is the spring constant of belt and  is related to load, tension, etc.It is assumed that ( A, B) is controllable and ( A, C ) is observable.The output error is defined by e  y  yr (2)The servo control system design is attempted by 3 steps as follows: [Step 1] eliminate the effect of disturbance in Eq. (1) by operating the polynomial differential operator of L( D)  Dq   q 1Dq 1  L  0 to both sides of Eqs. (1) and (2): d  {L( D) x}  AL( D) x  BL( D)u  dt (3)   L( D)e  CL( D) xwhere D  d ...