Management ship and working robots in waters based on wireless network and working robot control method thereof

1. A robot-ship group for executing a work operation on sea and river, the robot-ship group comprising:

at least one working robot;

a first mother ship having the at least one working robot; and

a second mother ship whose communication region is overlapped with a communication region of the first mother ship,

wherein the at least one working robot includes:

a signal strength measurement means for measuring strength of pre-defined signals transmitted from the first mother ship and the second mother ship; and

a working robot control means for determining which of the first mother ship and the second mother ship the at least one working robot is to communicate with according to a comparison result of the signal strength measured in the signal strength measurement means, and controlling the at least one working robot to perform the work according to a set-up route, and

wherein the first mother ship includes:

a working robot preparing unit for performing a preparation work required before and after the at least one working robot performs the work; and

a mother ship control unit for transmitting a pre-defined signal to the at least one working robot after said performing by the working robot preparing unit,

wherein the working robot control means calculates an average value of the signal strength measured by the signal strength measurement means at a predetermined time and determines which of the first mother ship and the second mother ship the at least one working robot is to communicate with.

2. The robot-ship group of claim 1 , wherein the working robot further includes:

an image/sensing means for providing image/sense information to the working robot control means in order to set up a route according to a route of a specific material or a specific object; and

a navigation measurement means for providing measurement information to the working robot control means in order to set up a route according to a command transmitted from the mother ship which is determined to perform communication with the working robots between the first mother ship and the second mother ship.

3. A robot-ship group for executing a work operation on sea and river, the robot-ship group comprising:

at least one working robot;

a first mother ship having the at least one working robot; and

a second mother ship whose communication region is overlapped with a communication region of the first mother ship,

wherein the at least one working robot includes:

a signal strength measurement means for measuring strength of pre-defined signals transmitted from the first mother ship and the second mother ship; and

a working robot control means for determining which of the first mother ship and the second mother ship the at least one working robot is to communicate with according to a comparison result of the signal strength measured in the signal strength measurement means, and controlling at least one working robots robot perform the work according to a set-up route, and

wherein the first mother ship includes:

a working robot preparing unit for performing a preparation work required before and after the at least one working robot performs the work; and

a mother ship control unit for transmitting a pre-defined signal to the at least one working robot after said performing by the working robot preparing unit,

wherein the working robot includes:

a collision object sensing means for sensing an object which may collide with the working robot in advance while the working robot is in motion or at a stand still, and

wherein the working robot control means senses a collision object in advance based on the information transmitted from the collision object sensing means and prevents collision.

4. The robot-ship group of claim 3 , wherein the working robot control means periodically checks whether the signal strength measured in the signal strength measurement means is the same or larger than a predetermined threshold, and determines which of the first mother ship and the second mother ship the at least one working robot is to communicate with.

5. The robot-ship group of claim 1 , wherein the working robot control means determines which of the first mother ship and the second mother ship the at least one working robot is to communicate with and maintains the received pre-defined signal strength on the basis of threshold in order to have an optimal signal strength for communication with the mother ship.

6. The robot-ship group of claim 5 , wherein although the at least one working robot is out of a communication region of the mother ship, the working robot control means changes a direction toward the mother ship based on location information of the mother ship included in the signals transmitted from the mother ship which is determined to communicate with the at least one working robot and reenters the communication region of the mother ship.

7. The robot-ship group of claim 1 , wherein the mother ship control unit authenticates the at least one working robot and the second mother ship by using pre-allocated encoding/decoding codes.

8. A method for controlling working robots for a work on sea and river through a wireless network formed by a first mother ship having at least one working robot for work on the sea or river and a wireless network formed by a second mother ship whose communication region is overlapped with the communication region of the first mother ship, the method comprising the steps of:

a) measuring strength of pre-defined signals transmitted from the first mother ship and the second mother ship;

b) comparing strength of the signals measured in the step a), and determining which of the first mother ship and the second mother ship the working robot is to communicate with; and

c) performing data communication with the determined mother ship and performing a work according to a set-up route, wherein the step c) includes the steps of:

c1) when the working robot is determined to communicate data with the second mother ship, requesting the first mother ship for information needed to communicate with the second mother ship;

c2) when the requested information is received from the first mother ship, notifying movement into the communication region of the second mother ship to the first mother ship and requesting the second mother ship for a temporary communication address; and

c3) ending communication with the first mother ship upon the receipt of the temporary communication address and communicating with the second mother ship based on the temporary communication address.

9. The method of claim 8 , wherein in the step c), the route is set up according to a route of a specific material or a specific object, or set up according to a command transmitted from the mother ship.

10. The method of claim 8 , wherein in the step c), an object which is on the route and may collide with the working robot is sensed in advance, and location of the working robot is changed.

11. The robot-ship group of claim 1 , wherein the mother ship control unit is also for communicating data with the at least one working robot through an authenticated second mother ship upon communication request of the working robot.

12. A method for controlling working robots for a work on sea and river through a wireless network formed by a first mother ship having at least one working robot for work on the sea or river and a wireless network formed by a second mother ship whose communication region is overlapped with the communication region of the first mother ship, the method comprising the steps of:

a) measuring strength of pre-defined signals transmitted from the first mother ship and the second mother ship at a predetermined time;

b) comparing strength of the signals measured in the step a), and determining which of the first mother ship and the second mother ship the working robot is to communicate with; and

c) performing data communication with the determined mother ship and performing a work according to a set-up route.