SAFETY DEVICE AND PREPARATORY MOVEMENT DETERMINATION METHOD

• US 20120279285A1
• Filed: 06/28/2012
• Published: 11/08/2012
• Est. Priority Date: 01/17/2011
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: KATO, Yumiko, OZAWA, Jun
• Granted Patent: US 8,695,406 B2
• Time in Patent Office: Days
• US Class Current: 73/65.01
• CPC Class Codes: B21D 5/02 on press brakes without making use of clamping means
• CPC Class Codes: B21D 55/00 Safety devices protecting the machine or the operator, specially adapted for apparatus or machines dealt with in this subclass for presses in general B30B; safety devices in general F16P
• CPC Class Codes: B30B 15/285 preventing a full press stroke if there is an obstruction in the working area
• CPC Class Codes: F16P 3/12 with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine F16P3/08 takes precedence

Abstract

A safety device for a machine having an action part for processing or moving an object includes: a posture obtainment unit configured to obtain a plurality of posture data indicating a posture of at least part of the lower body of a worker; and a preparatory movement determination unit configured to determine that a preparatory movement preceding a dangerous movement which brings at least part of the upper body of the worker closer to a working area of the action part is being performed in the case where a change in the posture indicated by the plurality of posture data shows that the worker is shifting a center of gravity of whole body of the worker in an orientation away from the working area of the action part without changing positions of both feet.

Claims

1. A safety device for a machine having an action part for processing or moving an object, said safety device comprising:

a posture obtainment unit configured to obtain a plurality of posture data indicating a posture of at least a part of a lower body of a worker; and

a preparatory movement determination unit configured to determine that a preparatory movement preceding a dangerous movement is being performed in the case where a change in the posture indicated by the plurality of posture data shows that the worker is shifting a center of gravity of whole body of the worker in an orientation away from a working area of the action part without changing positions of both feet, the dangerous movement being a movement of at least a part of an upper body of the worker approaching the working area of the action part.

2. The safety device according to claim 1,

wherein the plurality of posture data include a pressure distribution of soles of feet of the worker, and

said preparatory movement determination unit is configured to determine that the preparatory movement is being performed in the case where a position specified by the pressure distribution is moving in an orientation away from the working area of the action part.

3. The safety device according to claim 2,

wherein the position specified by the pressure distribution is a center-of-gravity position of the pressure distribution.

4. The safety device according to claim 3,

wherein said preparatory movement determination unit is configured to determine that the preparatory movement is being performed in the case where the center-of-gravity position is shifting in the orientation away from the working area of the action part and a moving speed, a moving time, or a moving distance of the center-of-gravity position in the orientation away from the working area of the action part is greater than or equal to a first threshold value.

5. The safety device according to claim 4,

wherein said preparatory movement determination unit is configured to determine that the preparatory movement is being performed in the case where the center-of-gravity position is shifting in an orientation away from the working area of the action part and a moving speed, a moving time, or a moving distance of the center-of-gravity position in the orientation away from the working area of the action part is from greater than or equal to the first threshold value to less than a second threshold value.

6. The safety device according to claim 3, further comprising

a distance detection unit configured to detect a distance between the working area of the action part and the worker,

wherein said preparatory movement determination unit is configured to determine that the preparatory movement is being performed in the case where the center-of-gravity position is shifting in an orientation away from the working area of the action part and the distance is less than a third threshold value.

7. The safety device according to claim 6, further comprising:

a size detection unit configured to detect a size of at least a part of the body of the worker; and

a correction unit configured to correct the detected distance such that when the size of the at least a part of the body of the worker is larger, the distance is shorter,

wherein said preparatory movement determination unit is configured to determine that the preparatory movement is being performed in the case where the center-of-gravity position is shifting in the orientation away from the working area of the action part and the corrected distance is less than the third threshold value.

8. The safety device according to claim 3, further comprising

an orientation detection unit configured to detect a body orientation of the worker,

wherein said preparatory movement determination unit is configured to determine that the preparatory movement is being performed in the case where the center-of-gravity position is shifting in an orientation away from the working area of the action part and an angle formed between the body orientation of the worker and an orientation of the working area of the action part seen from the worker is within a predetermined range.

9. The safety device according to claim 3, further comprising

a preparatory movement definition storage unit configured to store a first threshold value,

wherein said preparatory movement determination unit is configured to determine that the preparatory movement is being performed in the case where the center-of-gravity position is shifting in an orientation away from the working area of the action part, and a moving speed, a moving time, or a moving distance of the center-of-gravity position in the orientation away from the working area of the action part is greater than or equal to the stored first threshold value.

10. The safety device according to claim 9, further comprising

a distance detection unit configured to detect the distance between the working area of the action part and the worker,

wherein said preparatory movement definition storage unit is configured to store a plurality of first threshold values including the first threshold value in association with distances between the working of the action part area and the worker, and

said preparatory movement determination unit is configured to (i) specify a first threshold value corresponding to the detected distance among the plurality of the first threshold values stored in said preparatory movement definition storage unit and (ii) determine that the preparatory movement is being performed in the case where the center-of-gravity position is shifting in an orientation away from the working area of the action part, and a moving speed, a moving time, or a moving distance of the center-of-gravity position in the orientation away from the working area of the action part is greater than or equal to the specified first threshold value.

11. The safety device according to claim 10, further comprising:

a size detection unit configured to detect a size of the soles of feet of the worker based on the pressure distribution; and

a correction unit configured to correct the detected distance such that when the size of the soles of feet of the worker is larger, the distance is shorter,

wherein said preparatory movement determination unit is configured to specify the first threshold value corresponding to the corrected distance among the plurality of the first threshold values.

12. The safety device according to claim 2,

wherein said posture obtainment unit is configured to obtain, from a pressure sensor installed on a floor surface, the plurality of posture data including the pressure distribution of the soles of feet of the worker.

13. The safety device according to claim 1, further comprising

a safety operation control unit configured to slow down or stop the action part in the case where it is determined that the preparatory movement is being performed.

14. A preparatory movement determination method for preventing a worker from being injured by a machine having an action part for processing or moving an object, said preparatory movement determination method comprising:

obtaining a plurality of posture data indicating a posture of at least a part of a lower body of the worker; and

determining that a preparatory movement preceding a dangerous movement is being performed in the case where a change in the posture indicated by the plurality of posture data shows that the worker is shifting a center of gravity of whole body of the worker in an orientation away from a working area of the action part without moving positions of both feet, the dangerous movement being a movement of at least a part of an upper body of the worker approaching the working area of the action part.

15. A non-transitory computer-readable recording medium having a program recorded thereon for causing a computer to execute the preparatory movement determination method according to claim 14.