Rudder Actuation System for an Autonomous System PRESENTED BY:

T.NAGARAJU,

14341D6811, VLSI & ESD , ECE DEPT.Under The guidance Of Ch. Kalyan Chakravarthi, Assistant professor, Department Of ECE.

Abstract- This paper describes design,

test and evaluate of a Rudder actuation system for an autonomous vehicle. Autonomous vehicle consists of GPS system interfaced with rudder actuation system which is used to guide the ship towards destination without human interface. This system is used to replace the existing hydraulic actuators which are currently used to control the fin's position. Rudder actuation system uses 8051 Microcontroller to control the fin’s position which gives more accuracy in position control when compared with Hydraulic actuators. Subsequently, the performance of the whole Rudder actuation system and especially the behavior of the controller have been tested with different handling maneuvers.

Introduction A Rudder is a device used to steer a ship, boat,

submarine, hovercraft or other conveyance that moves through water .

In small craft the rudder is operated manually by a handle termed a tiller or helm.

There is a strong desire to remove humans from this task.

In larger ships, the rudder is controlled by hydraulic actuators.

Hydraulic actuators have following disadvantages:

low reliability, high pressure seals which may leak, High consumables like oil/cleaning/flushing fluid are required, requires more weight and space, requires more power consumption. So there is a need to over come these drawbacks by using some control mechanism.

METHODOLOGY Block diagram of the controller board

is shown in figure .

The block diagram consists of following blocks: Microcontroller8051, keypad, LCD, GPS, Driver and DC motor.

Microcontroller is the main block of the system. User feeds the source and target information through keypad to the microcontroller. Through GPS, microcontroller extracts current location of the ship.

Using source, destination, and current values, the controller calculates the angle to which the rudder has to be rotated. This angle is feed to the driver which drives the DC motor.

Keypad and LCD:

Keypad: 4X4 Keypad is used to provide source and target information to the microcontroller.

This keypad is interfaced to port 0 of microcontroller through RS232 cable.

LCD: LM016L Hitachi Display is connected to the microcontroller using a data cable through port 1.

LCD receives longitude and latitude information through GPS and displays the same on LCD screen.

Pins 5, 6, 7 of port 1 are used for enable, write and read operation.

GPS interface: In this work, the ProGin SR-95 GPS system is used. This GPS system is interfaced to port 3 of microcontroller through RS232 cable.

The GPS system gives the current position information about the ship to Microcontroller and the same is displayed on LCD.

GPS gives the data in NMEA (National Marine Electronics Association) format

The GPS module continuously transmits serial data (RS232 protocol) in the form of sentences according to NMEA Standards.

Triangulation is the process of determining the location of a point by measuring angles to it from known points. Triangulation Method

Overview can be shown as:

Figure 1: Triangulation Method Overview

Figure 2 : Angle Calculation.

calculation of the angle

A, B, C are the source, current and destination positions and a, b, c are the distance between B and C, A and C, A and B. The formula used by the Microcontroller to calculate error is as given in the equations: β=cos −1⎛⎜⎜⎝ a2 +2cac

2 −b2 ⎞ ⎟⎟ ⎠ ………………. (2)

= −⎛180⎞ β error _angle 180 ⎜ ⎟ ………. (3)

⎝ π ⎠

DRIVER and DC motor: The DRIVER which drives the motor is interfaced with the microcontroller as shown in the figure 1.

Port line 2, 6, 7 of port 2 is used as anticlockwise, enable, clockwise respectively.

Data is sent to the driver which defines the turn angle of the ship for particular generated error angle.

The rudder which controls the movement of ship is attached to the DC geared motor. When there is any deviation from the desired path microcontroller generates an error signal.

This error signal is given to the Geared DC Motor through the driver. Depending on the error angle generated, motor rotates through a specified number of degrees to correct the error.

The above discussed procedure is to calculate the error angle at particular instant of time.

The concept is repeated again and again until the ship has reached the specified target point.

RESULTS Error angle is calculated by using Mathlab. The same is verified using Microcontroller and DC motor.

Table 1: Mathlab Calculated Test Results.

Table 2: System Test Results

Also, 0.312 ms is the measured reaction time of the system. This is the minimum time required to drive the motor after calculating the error angle, by the microcontroller.

The snap shot of the overall system is shown in

figure 3.

Figure 3: Snapshot of overall system.

CONCLUSION: In this work, Microcontroller 8051 is used for controlling the rudder the same can be replaced with high end Microcontrollers. The GPS ProGin SR-95 gives accuracy of 2meters, whereas, manufacturing accuracies of the order of 0.001 meter or better are needed. There is a strong desire to remove humans from this task.In this work a detailed analysis and design of GPS controlled navigation is carried out to generate accurate rudder angle in minimum time. So if we go for high end GPS we can still improve our system performance. In Geared DC motor, the error in rotation is of 2o and there is a problem of inertia also. These errors can be reduces by using advanced motors like servo motors.

REFERENCE:1. 2009 International Conference on Advances in Computing, Control, and Telecommunication Technologies. Rudder Actuation System for an Autonomous System. Research scholar, R. V. Center for Cognitive Technologies, Bangalore, India .Email ID: nkotrick@gmail.com.

1 .Fossen, T. I., “Guidance and Control of Ocean Vehicles”. John Wiley & Sons Ltd. 1994 2. K. D. Do, Z. P. Jiang, and J. Pan, “Under actuated ship global tracking under relaxed conditions”, IEEE Trans. Autom. Control, vol. 47, no. 12,pp1529-1536, dec2009 3. Measurement by the use of triangles http://en.wikipedia.org/wiki/Triangulation 4. T.I. Fossen, “Marine Control Systems”, Marine Cybernetics AS, 2002 5. Than Htike, Tin That Ngwe and Yin Mon Myint, “Practical Approach to Rudder Control System for UAV using Low Cost MEMS Sensors”, 2008

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