Control system, moving robot apparatus having the control system, and a control method thereof

• US 8,055,385 B2
• Filed: 01/23/2007
• Issued: 11/08/2011
• 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
• Primary Examiner(s): Tran; Khoi
• Assistant Examiner(s): Holwerda; Stephen
• Application Number:
  US11/625,986
• Publication Number:
  US 20070255452A1
• Time in Patent Office: 1,750 Days
• Field of Search: 333/56, 333/57, 333/61, 333/55.R, 324/244, 324/225, 324/207.12, 324/200, 324/202, 359/879, 701/92, 701/224, 701/245, 700/245, 700/258, 702/5
• US Class Current: 700/258
• 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 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 via a necessary condition determining part 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 an external magnetic field interference;

extracting via a data estimator 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 via a weight calculator 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 via the data estimator the current direction of the robot main body based on the extracted current sample value and the calculated weight, wherein the weight is a probability of obtaining a current data from a sample value at a present time, wherein the current direction estimated via the data estimator is at least one of stored in memory and included within the direction-related data provided to the robot main body from the data estimator.

2. The control method according to claim 1, 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.

3. The control method according to claim 2, 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.

4. 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:

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

 

<

Equation 1>

Wt=p(Z_tX_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 external magnetic field interference, C^c is an event where the current data are affected by the external magnetic field interference, V is an event that satisfies the necessary condition when the sensor part does not have a data distortion due to the external magnetic field 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 external magnetic field interference.

5. The control method according to claim 4, wherein the sensor part comprises a magnetic compass.

6. 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 using a particle filter.

7. The control method according to claim 2, 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:

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

 

<

Equation 1>

Wt=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 external magnetic field interference, C^c is an event where the current data are affected by the external magnetic field interference, V is an event that satisfies the necessary condition when the sensor part does not have a data distortion due to the external magnetic field 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 external magnetic field interference.

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

9. The control method according to claim 7, 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.

10. The control method according to claim 1, 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;

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

 

<

Equation 1>

Wt=p(Z_t|X_tC,V^c)p(C|V^c(p(Z_t|X_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 external magnetic field interference, C^c is an event where the current data are affected by the external magnetic field interference, V is an event that satisfies the necessary condition when the sensor part does not have a data distortion due to the external magnetic field 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 external magnetic field interference.

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

12. The control method according to claim 10, 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.

13. The control method according to claim 1, further comprising positioning the robot main body in a next direction based on the estimated current direction.

14. 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 the earth'"'"'s magnetic field;

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, wherein the necessary condition is considered to be satisfied when the current data output are unaffected by an external magnetic field interference; 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, wherein the estimated current direction is at least one of stored in memory and included within the direction-related data provided to the robot main body.

15. The moving robot apparatus according to claim 14, wherein the sensor part comprises a magnetic compass.

16. The moving robot apparatus according to claim 14, 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.

17. The moving robot apparatus according to claim 16, 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.

18. The moving robot apparatus according to claim 14, 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 external magnetic field interference, C^c is an event where the current data are affected by the external magnetic field interference, V is an event that satisfies the necessary condition when the sensor part does not have a data distortion due to the external magnetic field 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 external magnetic field interference.

19. The moving robot apparatus according to claim 18, wherein the data estimator comprises a particle filter.

20. The moving robot apparatus according to claim 14, 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.

21. 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 the earth'"'"'s magnetic field;

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 an external magnetic field 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, wherein the estimated current direction is at least one of stored in memory and included within the direction-related data provided in the main body.

22. The processor containing the method according to claim 21, 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.

23. The processor containing the method according to claim 21, 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.

24. 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 the earth'"'"'s magnetic field;

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 an external magnetic field 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, wherein the current estimated direction is at least one of stored in memory and included within the direction-related data provided to the main body.