CONTROL SYSTEM, MOVING ROBOT APPARATUS HAVING THE CONTROL SYSTEM, AND A CONTROL METHOD THEREOF

• US 20070255452A1
• Filed: 01/23/2007
• Published: 11/01/2007
• Est. Priority Date: 04/04/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Roh, Kyung-shik, KWON, Woong
• Granted Patent: US 8,055,385 B2
• Time in Patent Office: Days
• US Class Current: 700/245
• CPC Class Codes: G05D 1/0259 using magnetic or electromagnetic means

Abstract

A moving robot apparatus and a control system and method thereof. A current state variable (e.g., the current direction of the main body of the robot apparatus) may be estimated using current data output from a sensor part of the robot apparatus. Initially, it is determined whether the current data output from the sensor part satisfy a necessary condition. The necessary condition may be considered to be satisfied when the current data are unaffected by a disturbance or external interference (e.g., the earth'"'"'s magnetic field.). Thereafter, a current sample value may be extracted from a previous sample value obtained from the sensor part. The previous sample value may relate to a previous state variable (e.g., a previous direction of the robot main body). A weight of the current data may be calculated based on the current sample value. A value of the weight may depend on whether the necessary condition is satisfied by the current data. The current state variable is then estimated based on the extracted current sample value and the calculated weight. A control of the directional movement of the robot main body may be provided based on the estimated current state variable. A control system may be provided to accurately estimate, using a probability distribution, the direction of the robot main body when it can not be determined whether or not an external disturbance is reflected in the data output from the sensor part.

Claims

1. A method to estimate a current state variable using current data output from a sensor part in a control system, the method comprising:

determining whether the current data output from the sensor part satisfy a necessary condition;

extracting a current sample value from a previous sample value from which a previous state variable is obtained;

calculating a weight of the current data based on the current sample value, wherein a value of the weight depends on whether the necessary condition is satisfied by the current data; and

estimating the current state variable based on the extracted current sample value and the calculated weight.

2. The method according to claim 1, further comprising:

considering the necessary condition as satisfied when the current data output are unaffected by a disturbance.

3. A method of controlling a moving robot apparatus having a robot main body and a sensor part that outputs current data related to a current direction of the robot main body with respect to the earth'"'"'s magnetic field, the method comprising:

determining whether the current data output from the sensor part satisfy a necessary condition, wherein the necessary condition is considered to be satisfied when the current data output from the sensor part are unaffected by the earth'"'"'s magnetic field;

extracting a current sample value from a previous sample value obtained from the sensor part, wherein the previous sample value relates to a previous direction of the robot main body;

calculating a weight of the current data based on the current sample value, wherein a value of the weight depends on whether the necessary condition is satisfied by the current data; and

estimating the current direction of the robot main body based on the extracted current sample value and the calculated weight.

4. The control method according to claim 3, wherein the estimating the current direction of the robot main body comprises calculating a probability distribution using the extracted current sample value and the calculated weight and by repeating the extracting the current sample value and the calculating the weight by a predetermined number of times.

5. The control method according to claim 4, wherein the estimating the current direction of the robot main body further comprises:

estimating the current direction of the robot main body based on a mean value of the calculated probability distribution.

6. The control method according to claim 5, wherein the calculating the weight of the current data based on the current sample value comprises calculating the weight of the current data according to the following equation 1 when the current data satisfy the necessary condition, and according to the following equation 2 when the current data do not satisfy the necessary condition:

p(Z_t|X_t, C, V)p(C|V)+p(Z_t|X_t, C^c, V)p(C^c|V)  

 

<

Equation 1>

p(Z_t|X_t, C, V^c)p(C|V^c)+p(Z_t|X_t, C^c, V^c)p(C^c|V^c)  

 

<

Equation 2>

where, Z_t is current data at a present time t, X_t is an estimated value of a robot direction at the present time t, C is an event where the current data do not have a data distortion due to the earth'"'"'s magnetic field interference, C^c is an event where the current data are affected by the earth'"'"'s magnetic field interference, V is an event that satisfies the necessary condition when the sensor part does not have a data distortion due to a disturbance from the earth'"'"'s magnetic field, and V^c is an event that does not satisfy the necessary condition when the sensor part does not have a data distortion due to a disturbance from the earth'"'"'s magnetic field.

7. The control method according to claim 6, wherein the sensor part comprises a magnetic compass.

8. The control method according to claim 6, wherein the estimating the current direction of the robot main body further comprises:

estimating the current direction of the robot main body using a particle filter.

9. The control method according to claim 4, wherein the calculating the weight of the current data based on the current sample value comprises calculating the weight of the current data according to the following equation 1 when the current data satisfy the necessary condition, and according to the following equation 2 when the current data do not satisfy the necessary condition:

p(Z_t|X_t, C, V)p(C|V)+p(Z_t|X_t, C^c, V)p(C^c|V)  

 

<

Equation 1>

p(Z_t|X_t, C, V^c)p(C|V^c)+p(Z_t|X_t, C^c, V^c)p(C^c|V^c)  

 

<

Equation 2>

where, Z_t is current data at a present time t, X_t is an estimated value of a robot direction at the present time t, C is an event where the current data do not have a data distortion due to the earth'"'"'s magnetic field interference, C^c is an event where the current data are affected by the earth'"'"'s magnetic field interference, V is an event that satisfies the necessary condition when the sensor part does not have a data distortion due to a disturbance from the earth'"'"'s magnetic field, and V^c is an event that does not satisfy the necessary condition when the sensor part does not have a data distortion due to a disturbance from the earth'"'"'s magnetic field.

10. The control method according to claim 9, wherein the sensor part comprises a magnetic compass.

11. The control method according to claim 9, wherein the estimating the current direction of the robot main body comprises estimating the current direction of the robot main body using a particle filter.

12. The control method according to claim 3, wherein the calculating the weight of the current data based on the current sample value comprises calculating the weight of the current data according to the following equation 1 when the current data satisfy the necessary condition, and according to the following equation 2 when the current data do not satisfy the necessary condition:

p(Z_t|X_t, C, V)p(C|V)+p(Z_t|X_t, C^c, V)p(C^c|V)  

 

<

Equation 1>

p(Z_t|X_t, C, V^c)p(C|V^c)+P(Z_t|X_t, C^c, V^c)p(C^c|V^c)  

 

<

Equation 2>

where, Z_t is current data at a present time t, X_t is an estimated value of a robot direction at the present time t, C is an event where the current data do not have a data distortion due to the earth'"'"'s magnetic field interference, C^c is an event where the current data are affected by the earth'"'"'s magnetic field interference, V is an event that satisfies the necessary condition when the sensor part does not have a data distortion due to a disturbance from the earth'"'"'s magnetic field, and V^c is an event that does not satisfy the necessary condition when the sensor part does not have a data distortion due to a disturbance from the earth'"'"'s magnetic field.

13. The control method according to claim 12, wherein the sensor part comprises a magnetic compass.

14. The control method according to claim 12, wherein the estimating the current direction of the robot main body further comprises:

estimating the current direction of the robot main body using a particle filter.

15. The control method according to claim 3, further comprising positioning the robot main body in a next direction based on the estimated current direction.

16. A control system that comprises a sensor part and estimates a current state variable using current data output from the sensor part, the control system comprising:

a necessary condition determining part operatively coupled to the sensor part and configured to set a necessary condition to be satisfied and to determine whether the current data output from the sensor part satisfy the necessary condition; and

a data estimator operatively coupled to the necessary condition determining part and configured to extract a current sample value from a previous sample value from which a previous state variable is obtained, to calculate a weight of the current data based on the current sample value, wherein a value of the weight depends on whether the necessary condition is satisfied by the current data, and to estimate the current state variable based on the extracted current sample value and the calculated weight.

17. The control system according to claim 16, wherein the necessary condition is considered to be satisfied when the current data output are unaffected by a disturbance.

18. A moving robot apparatus comprising:

a robot main body;

a sensor part operatively coupled to the robot main body to output data related to a current direction of the robot main body with respect to an interference;

a necessary condition determining part operatively coupled to the sensor part and configured to set a necessary condition to be satisfied and to determine whether the current data output from the sensor part satisfy the necessary condition; and

a data estimator operatively coupled to the necessary condition determining part and the robot main body and configured to extract a current sample value from a previous sample value obtained from the sensor part, wherein the previous sample value relates to a previous direction of the robot main body, to calculate a weight of the current data based on the current sample value, wherein a value of the weight depends on whether the necessary condition is satisfied by the current data, and to estimate the current direction of the robot main body based on the extracted current sample value and the calculated weight.

19. The moving robot apparatus according to claim 18, wherein the necessary condition is considered to be satisfied when the current data output are unaffected by the interference.

20. The moving robot apparatus according to claim 18, wherein the interference includes the earth'"'"'s magnetic field.

21. The moving robot apparatus according to claim 20, wherein the sensor part comprises a magnetic compass.

22. The moving robot apparatus according to claim 18, wherein the data estimator is configured to calculate a probability distribution using the extracted current sample value and the calculated weight and by repeating operations of extracting the current sample value and calculating the weight by a predetermined number of times.

23. The moving robot apparatus according to claim 22, wherein the data estimator is configured to estimate the current direction of the robot main body based on a mean value of the calculated probability distribution.

24. The moving robot apparatus according to claim 18, wherein the data estimator comprises a weight calculator that is configured to calculate the weight of the current data based on the current sample value according to the following equation 1 when the necessary condition determining part determines that the current data satisfy the necessary condition, and according to the following equation 2 when the necessary condition determining part determines that the current data do not satisfy the necessary condition:

p(Z_t|X_t, C, V)p(C|V)+p(Z_t|X_t, C^c, V)p(C^c|V)  

 

<

Equation 1>

p(Z_t|X_t, C, V^c)p(C|V^c)+p(Z_t|X_t, C^c, V^c)p(C^c|V^c)  

 

<

Equation 2>

where, Z_t is current data at a present time t, X_t is an estimated value of a robot direction at the present time t, C is an event where the current data do not have a data distortion due to the interference, C^c is an event where the current data are affected by the interference, V is an event that satisfies the necessary condition when the sensor part does not have a data distortion due to the interference, and V^c is an event that does not satisfy the necessary condition when the sensor part does not have a data distortion due to the interference.

25. The moving robot apparatus according to claim 24, wherein the data estimator comprises a particle filter.

26. The moving robot apparatus according to claim 18, wherein the data estimator is configured to provide signals to the robot main body based on the estimated current direction so as to position the robot main body in a next direction.

27. A processor containing therein a method of controlling directional movement of a robotic apparatus, the method comprising:

receiving current data output by a sensor part of the robotic apparatus and related to a current direction of a main body of the robotic apparatus with respect to an external interference;

determining whether the current data output from the sensor part satisfy a necessary condition, wherein the necessary condition is considered to be satisfied when the current data output from the sensor part are unaffected by the external interference;

extracting a current sample value from a previous sample value obtained from the sensor part, wherein the previous sample value relates to a previous direction of the main body;

calculating a weight of the current data based on the current sample value, wherein a value of the weight depends on whether the necessary condition is satisfied by the current data; and

estimating the current direction of the main body of the robotic apparatus based on the extracted current sample value and the calculated weight.

28. The processor containing the method according to claim 27, wherein the estimating the current direction of the main body is performed by calculating a mean value of a probability distribution using the extracted current sample value and the calculated weight.

29. The processor containing the method according to claim 27, wherein the method further comprises:

providing signals to the main body of the robotic apparatus based on the estimated current direction so as to control directional movement of the main body.

30. A data storage medium containing program instructions, which, when executed by a processor in a robotic device, cause the processor to perform the following operations:

receive current data output by a sensor part of the robotic apparatus and related to a current direction of a main body of the robotic apparatus with respect to an external interference;

determine whether the current data output from the sensor part satisfy a necessary condition, wherein the necessary condition is considered to be satisfied when the current data output from the sensor part are unaffected by the external interference;

extract a current sample value from a previous sample value obtained from the sensor part, wherein the previous sample value relates to a previous direction of the main body;

calculate a weight of the current data based on the current sample value, wherein a value of the weight depends on whether the necessary condition is satisfied by the current data; and

estimate the current direction of the main body of the robotic apparatus based on the extracted current sample value and the calculated weight.