The present disclosure pertains to detection systems and particularly to object or person detection systems. More particularly, the disclosure pertains to detection systems for particular areas.
The disclosure reveals a system for detecting one or more items such as objects and/or persons in a specified zone. A determination is whether there is a person in the zone. A presence determination module may indicate from a current image of the zone compared with a reference image of the zone, whether there is, for example, a person in or not in the zone. An illumination controller may assure that the zone is sufficiently illuminated for a current image sufficient for comparison with the reference image to determine a possible presence of a person in the zone. The illumination may be infrared. The system may be used to assure appropriate and adequate face velocity at a fume hood having the presence of a person and having minimal face velocity in the absence of a person at the fume hood.
The present mechanism and approach may distinguish people and inanimate objects in a detection zone, for example, an area in front of a fume hood. When a person is detected in the zone, the system may increase face velocity of the hood to ensure safety. When the person leaves the detection zone, the system may decrease face velocity to save energy. If there is doubt about a presence of a person in the zone, then the system may maintain the increased face velocity of the hood to ensure safety. A default position of the system may be regarded as maintaining the increased face velocity of the hood.
Research by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) and other like entities have shown that when there is no person working in front of the fume hood, it is safe to reduce the face velocity from the industry norm of 100 ft./min. to a lesser value—being 60 ft./min. for a normal-sized fume hood (i.e., between six feet and ten feet but nominally about eight feet in width). The reduction of face velocity may provide up to a 40 percent energy savings when sashes are left open and the fume hood is not occupied. A range for a reduced face velocity where there is no person in a specified zone in front of the fume hood may be from 45 ft./min. to 75 ft./min. A nominal value for the reduced face velocity may be 60 ft./min. A range for a regular face velocity where there is a person in the specified zone in front of the fume hood may be from 85 ft./min. to 115 ft./min. A nominal value for the regular face velocity may be 100 ft./min. These face velocity values may be appropriate for a normal-sized fume hood (i.e., between six feet and ten feet but nominally about eight feet in width). Various conditions and structural elements of, for example, an eight foot wide fume hood, may result in face velocities different from the nominal velocities stated herein. A significant aspect of the present disclosure is that the nominal velocities may be different for assuring safety of a person in the zone and achieving economy without compromising safety in a situation where a person is not in the zone.
The zone presence sensor system (ZPS™—a Honeywell International Inc. trademark) may create a detection zone in front of the fume hood to determine if a researcher or other person is in front of the hood or if the zone is vacant. If no person is present, the ZPS may send a signal to the fume hood control system which allows it to reduce the face velocity to a value deemed appropriate by applicable health and safety standards. If a person moves into the detection zone, the ZPS may send a signal to the fume hood control system to return to the operational face velocity ensuring that the safety and fume hood containment are maintained. The present controls usage, based control (UBC) system sub 1-second speed of response, may provide maximum energy saving for two-state and variable air volume (VAV) fume hoods without compromising safety.
Several aspects of the ZPS may be noted. The ZPS may detect an operator presence or absence and send a “normal” or “standby” signal to the fume hood control system. The fume hood control system may adjust the airflow to achieve the desired normal and standby face velocity setpoints. Inanimate objects may be mapped into the image background. A configurable detection zone may accommodate various fume hood widths and corridor depths. Infrared emitting diodes (IRED) may provide illumination for reliable detection in low or no light conditions. High resolution color image sensor technology and high speed algorithms may ensure proper detection in a wide variety of lighting conditions. The less than 1-second speed of response may ensure safe operation under various operating conditions. A single ZPS may provide protection for fume hoods of a nominal eight foot width. Multiple ZPSs may be used together for protection at double and four-sided fume hoods or significantly wide fume hoods. Comprehensive fail-safe schemes may return the fume hood to the safest state under fault conditions.
If the zone presence sensor system may capture a detection zone image, then an algorithm along with other components of an analysis mechanism may compare the image with a reference image stored in memory and output a high or low (HI/LO) voltage signal to indicate whether there is a detection of a person or object in the zone. The reference image may be dynamically updated to reflect a background change in the detection zone. The zone presence sensor system may work in both a well-lit environment and total darkness. The zone presence sensor system may be insensitive to moving shadows. Multiple zone presence sensor systems may be daisy-chained to cover a larger area.
The zone presence sensor system may incorporate the following modules: 1) an image acquisition module; 3) an infrared illumination module; and 3) a microprocessor. The image acquisition module may capture a real-time digitized image. The infrared module may sense lighting level and, via the microprocessor, turn infrared illumination on or off, accordingly, as needed for sufficient lighting in quality image acquisition. The infrared illumination may also have a variable intensity. The microprocessor may perform image processing and comparison, and input/output (IO) control.
A comparison of a current image 16 and a reference image 18 may incorporate comparing pixels of the current image and pixels of the reference image to detect a difference of pixels between the current image and the reference image. The comparison may be advanced, for example, in which the difference is analyzed to determine whether a person is present or not in the specified zone 20.
Output 21 may be connected to a zone flow control module 31. Output 21 may be specifically connected to a flow controller 27 which may control certain conditions within the zone, such as environmental conditions. An example application of controller 27 may be for a zone 20 of an example fume hood 35 shown in
Lighting may be another component of sensor system 11. Infrared illumination module 14 may have an ambient light sensor 22 that senses an amount of lighting in zone 20 for adequate detection of a presence or non-presence of a person 25. Such indication may be provided to an illumination controller 23 in microprocessor 13. If the lighting is sufficient for detection purposes in zone 20, then the illumination controller 23 may do nothing. If the light is not sufficient, the illumination controller 23 may turn on a lighting arrangement 24. The lighting arrangement 24 may incorporate an infrared emitter source or a light source of another wavelength. The source may be a discrete on/off component or a component for providing a variation of lighting output. In case an emitter source has been off, or been on at a too low of an intensity level, lighting source or arrangement 24 may be turned on or increased in intensity to improve lighting in zone 20 so that image sensor 15 can obtain a current image 16 satisfactory for a determination by the presence detection mechanism 17 of whether a person 25 is present or not in zone 20.
Schematics of
A related U.S. Pat. No. 4,528,898, issued Jul. 16, 1985, and entitled “Fume Hood Controller”, is hereby incorporated by reference. A related U.S. Pat. No. 4,706,553, issued Nov. 17, 1987, and entitled “Fume Hood Controller”, is hereby incorporated by reference. A related U.S. Pat. No. 4,893,551, issued Jan. 16, 1990, and entitled “Fume Hood Sash Sensing Apparatus”, is hereby incorporated by reference. A related U.S. Pat. No. 5,117,746, issued Jun. 2, 1992, and entitled “Fume Hood Sash Sensing Apparatus”, is hereby incorporated by reference. A related U.S. Pat. No. 5,240,455, issued Aug. 31, 1993, and entitled “Method and Apparatus for Controlling a Fume Hood”, is hereby incorporated by reference. A related U.S. Pat. No. 5,406,073, issued Apr. 11, 1995, and entitled “System for Detecting a Movable Entity within a Selected Space”, is hereby incorporated by reference. A related U.S. Pat. No. 6,137,403, issued Oct. 24, 2000, and entitled “Sash Sensor and Method of Sensing a Sash Using an Array of Multiplexed Elements”, is hereby incorporated by reference. A related U.S. Pat. No. 6,711,279, issued Mar. 23, 2004, and entitled “Object Detection”, is hereby incorporated by reference. A related U.S. Pat. No. 6,841,780, issued Jan. 11, 2005, and entitled “Method and Apparatus for Detecting Objects”, is hereby incorporated by reference. A related U.S. Pat. No. 6,935,943, issued Aug. 30, 2005, and entitled “Wireless Communications for Fume Hood Control”, is hereby incorporated by reference. A related U.S. Pat. No. 7,176,440, issued Feb. 13, 2007, and entitled “Method and Apparatus for Detecting Objects Using Structured Light Patterns”, is hereby incorporated by reference. A related U.S. Pat. No. 7,184,585, issued Feb. 27, 2007, and entitled “Object Detection”, is hereby incorporated by reference. A related U.S. Pat. No. 7,768,549, issued Aug. 3, 2010, and entitled “Machine Safety System with Mutual Exclusion Zone”, is hereby incorporated by reference. A related Patent Application Publication No. 2008/0002856, published Jan. 3, 2008, and entitled “Tracking System with Fused Motion and Object Detection”, is hereby incorporated by reference. A related Patent Application Publication No. 2009/0191803, published Jul. 30, 2009, and entitled “Fume Hood System Having an Automatic Decommission Mode”, is hereby incorporated by reference. Although the patent documents noted herein are incorporated by reference, the present disclosure may be regarded as having sufficient support for the claims.
In the present specification, some of the matter may be of a hypothetical or prophetic nature although stated in another manner or tense.
Although the present system and/or approach has been described with respect to at least one illustrative example, many variations and modifications will become apparent to those skilled in the art upon reading the specification. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.