UNMANNED VEHICLES (i-UV)

ROV (Remotely Operated Vehicle) is the general name given to underwater robots, which are used in underwater research, search and a variety of applications. ROVs were first used by the military, but since the 1980’ies when the production costs dropped its use became widespread. ROVs are classified according to their sizes to three groups: work class, general and mini.

CI-Dragon is a mini ROV developed by Ideal Technology. The low cost and the easy transport nature of the vehicle give it a wide spectrum of use. CI-Dragon which can operate at 150 meters below water can be used in the regular control of underwater life and underwater pollution, in the investigation of sunken stuff, as an immediate investigation in emergency operations and in industrial applications (such as the investigation of pipes and damaged location of cables).

The majority of underwater robots today are controlled manually by users. Autonomous robots, on the other hand, are hardly in use because underwater conditions (light, currents, flora, seabed etc.) create a complex variety of factors.

Our aim is to develop a program which allows semi autonomous features for a CI-Dragon, which is easy to use and easy to review the records, taking into account the above mentioned conditions.

METHOD

CI-Dragon v1.1 is software developed in order to control the robot.

Keeping portability and object oriented program development in mind, CI-Dragn v1.1 was developed on the .Net platform on the Windows operating system using the C# language. DirectX 9.0 libraries were used for video capture, recording, and joy pad control. The .Net platform and the DirectX 9.0 are free software that comes provided with a Windows operating system. Sensory data is collected from the CI-Dragon robot and transmitted to the laptop via the RS 485 protocol. The software receives this data from the RS232 port with the help of a converter. A USB TV-Capture card captures images from the camera. A joypad, also connected to the computer via USB controls the robots thrusters and camera orientation. All the data sent and collected from the session are stored in a binary data file and a video file. Thanks to the Image processing and artificial Intelligence techniques used the user is able to give semi autonomous control to the robot.

The project is developed with an object oriented mentality and has a modular structure. Documentation for the software is developed simultaneously.

RESULTS

• Displays:The data collected from the robot are processed by the program and then presented to the user by means of simple and easily understood layouts.
  • Depth Display: CI-Dragon has an operating depth of 150 meters. The depth display automatically shifts to the left, constantly displaying the depth profile of the last 75 seconds of the dive. As the depth increases the color of the plot turns form blue to red. The max depth reached during the whole dive is shown as [max:xxx].
  • Temperature Display: The temperature is shown in Celsius.
  • Compass and Orientation Display: Two compasses are used for the orientation display of the robot. One of these compasses is situated on the robot whereas the other is on the laptop. The gray line in the middle of the display symbolizes the direction the person is sitting. The user can see which direction he is facing using the compass. The picture of the red robot symbolizes the orientation of the robot. Thanks to this design the user is able to see which direction the robot is facing even on a boat that constantly changes direction.
  • Thruster Power and Thruster Control Display: Displays the level of thrust provided by the 3 thrusters on the robot. Displays the data from the motor control device.
  • Camera Control Unit: Displays the data from the camera control device.
  • Date and Time Display and Playback Control: The date, time and total operation time is displayed during operation. During playback the date time and total operation time of the playback is displayed. During playback the width of the slider bar is the total session time. Playback can be scanned forward and backward in an easy manner.

• Robot and Camera Control: Communication between the Robot's microprocessor and the surface control unit is achieved with the RS 485 protocol; this is translated to the RS232 protocol by means of an adapter attached to the surface control unit. Control signals are sent to the robot every 40 ms (25Hz). Simultaneously Images from the robot are transferred over a coaxial cable every 40 ms (25 Hz) and received by the TV-Capture Card. The control unit is divided In two. The left side is for motor control whereas the right side is for camera control. If a software or hardware error is detected the user is warned by vibration of the control unit.

• Recording and Playback: CI-Dragon v1.1 has two different modes of operation:
  • The first is "Real-time operation mode", the robot is controlled in real-time. In this mode the data that comes from the robot and visual information from the camera is processed and displayed and the camera control and motor control input to the control unit is sent to the robot. All the processes done and all signals exchanged during the session can be logged. This is saved as two separate files. The first contains the Video coming from the robot camera; the second file contains all other data exchanged. Keeping the log of the session in two different files enables the session to be distributed in VCD and DVD format, with the data displayed as subtitle. This greatly facilitates the distribution and analysis of the session.
  • The other mode of operation is the "Simulation mode". In the simulation mode, data stored can be reviewed. The video file (.avi) and the data file (.cid) are specified. And then the session starts replay. All data are read from the file provide instead of the serial port. Image and sensory data are stored in the same frequency. The sensory data file also keeps track of the frame number corresponding to the data. This assures that the image and the data displayed is always synchronized. The session can be easily evaluated thanks to this mode.

• Semi Autonomous Control: CI-Dragon has been designed with semi autonomous control in mind. The user mainly controls the robot manually, but some tasks can be left to the robot control software.
  • Depth Control: The depth of the robot can be set. In this case the program maintains the depth. The user controls movements of the robot, but up and down thrust controls become nonfunctional as the software controls the thruster for vertical thrust.
  • Direction Control: Enables the robot to move in a certain direction without drifting away from its path. The thrust of the thrusters is controlled automatically. The only thing the user can do is make the robot move forward or backward.
  • Fixed Camera View: During operations where the current is present, observing objects becomes difficult. With the help of this functionality the robots camera is able to follow objects. If the object goes out of view then the camera is returned to its default position.
  • Line Following: The robot will also be able to follow lines or other detectable objects like pipes. The image is processed and the object to be followed is extracted from the image, and from this data the direction is obtained.

DISCUSSION

Despite the fact that CI-Dragon v1.1 brings numerous novelties to semi autonomous control, some aspects still remains unsolved. There is currently no collision control, and the robot could be seriously damaged by a collision at depth. To solve this problem, depth of vision can be calculated with the help of lasers. The software will detect lasers at fixed angles sent to the field of vision of the robot. The distance and slope In the Image viewed can be calculated. Also these lasers can provide means of computation of the size of objects. This will facilitate usage, by means of warning the user if the robot comes too close to any objects. Further research on collision detection and tether management is being done.

CONCLUSION

CI-Dragon is a program which is developed with the latest technology and which facilitates the usage of underwater robots by means of semi autonomous features and allows the input to be saved and reviewed. With the new features, which are added, it is progressing to be a model program in its field.