Improving Elevator Performance by Monitoring Elevator Cab Volume by James O’Laughlin

EW ECO-ISSUES: Continuing Education

Learning Objectives After reading this article, you should: N Understand why some elevator applications have the problem of full elevator cabs stopping unnecessarily to service hall calls. N Be able to describe several methods that help minimize the problem of full elevator cabs stopping unnecessarily to service hall calls. N Recognize why camera technology provides a better solution for monitoring consumed elevator- cab volume. N Know the application require-

ments for monitoring consumed CEDES ESPROS/VOL camera installation (photo elevator-cab volume using courtesy of New York Elevator) infrared camera technology. sponding to hall calls. Increasing the N Obtain knowledge regarding the number of elevators is one possibil- installation and operation of the ity, but is generally cost prohibitive. CEDES ESPROS/VOL Camera Destination-dispatch systems can sensor. also help to alleviate this issue. How- ever, destination-dispatch systems Optimal elevator system perform- are best implemented in new instal- ance has always been a concern for lations, and also may be cost prohib- facilities and building management. itive for modernization applications. People expect that the elevator will More cost-effective solutions include Value: 1 contact hour arrive shortly after they press the hall using load-weighing systems or call button. When the elevator ar- camera-based monitoring to deter- This article is part of ELEVATOR WORLD’s mine a threshold that corresponds to rives, people are disappointed when Continuing Education program. Elevator-industry it is full, and they have to press the the consumed volume inside the ele- personnel required to obtain continuing-education hall call button and wait for the next vator cab. Once the threshold value credits can receive one hour of credit by reading car. The delays and inconvenience has been reached, the elevator con- the article and completing the assessment exami- caused by full cabs arriving to service trol system can perform a bypass or nation questions found on page 149. hall calls are not appreciated. Equally an express run that minimizes or For this article and more continuing-education annoyed are passengers currently in eliminates the unnecessary stops. opportunities, visit www.elevatorbooks.com the elevator who are unnecessarily However, load-weighing systems NATIONAL ASSOCIATION OF ELEVATOR CONTRACTORS ® delayed as they stop for hall calls that cannot improve elevator performance Approved by NAEC for CET CERTIFIED ELEVATOR TECHNICIAN cannot be serviced because the ele- when the consumed elevator cab EDUCATION PROGRAM vator cab is already full of passengers. volume does not correspond to the Approved by NAESAI for QEI Several methods can be used to measured weight. This is particularly minimize the instance of full cabs re- true when elevator loads include Continued November 2008 | ELEVATOR WORLD | 73 EW ECO-ISSUES: Continuing Education Continued passengers and other items such as N The elevator operational control (i.e., ESPROS/VOL field of view) is luggage carts in hotels, gurneys and system must have an electrical 2.9 m X 2.2 m (9.4 ft. X 7.1 ft.) beds in hospitals, or wheelchairs in input that supports the bypass or maximum. Areas larger than this nursing homes. For these and similar express run function. The output can be addressed using two or types of circumstances, measuring from the ESPROS/VOL camera is more cameras, e.g. by series con- the actual consumed volume inside 24 VDC when the percentage nection of signal relay contacts. the elevator cab provides the only change required by the threshold N Mirrored surfaces may result in real solution that addresses this value has been met or exceeded. “double counting.” This results challenge. Particular attention is required for from counting the pixel changes Camera-Based Volume Monitoring hydraulic elevator applications caused by the actual load (e.g., The ESPROS/VOL is a camera- when the bypass function is ac- person) and then counting pixel based system that can operate as complished using fluid dynamics changes also reflected by the mir- part of a stand-alone system or with rather than electrical control. rored surface. This specifically a load-weighing system to help de- N Infrared cameras rely on infrared occurs when the mirrored surface termine when a “cab full” condition light present inside the elevator is within the camera’s field of view. exists. This product is manufactured cab. Halogen lighting provides an When these application require- by CEDES AG in Landquart, Switzer- efficient means of fulfilling this ments are adequately addressed, an land, and is an intelligent vision requirement. However, when flu- infrared camera-based monitoring sensor that uses infrared comple- orescent lighting is the sole source system may be used for measuring mentary metal-oxide-semiconductor of lighting in the elevator cab, an the consumed volume inside an ele- camera technology. The micro- additional infrared light source may vator cab and signaling that a bypass processor inside the device provides be necessary to ensure adequate or express run condition has occurred. a camera image of more than 100,000 ambient infrared light is available. Mounting Considerations gray-scale pixels. The internal soft- N Consistent lighting inside the ele- The mounting location and orien- ware algorithm then compares the vator cab is also required. Lighting tation of an ESPROS/VOL infrared current pixel image against a reference variation caused by direct or indi- camera is critical to performance. image stored in its internal memory. rect sunlight showing through a There are two model types: one for When the percentage of pixels that glass window will impact system ceiling mounting (ESPROS/VOL-V) have changed meets or exceeds the performance negatively. For non- with a vertical view and one for wall user-defined “cab full” threshold, an glass enclosed elevators, this is mounting (ESPROS/VOL-A) with an output is generated. The elevator op- generally not an issue as the pixel angled view. The sensor may be erational control can then perform a comparison used to determine inconspicuously mounted due to its bypass or an express run to the des- whether or not the bypass thresh- small size (the housing is 126 mm tination floors selected from inside old has been reached should occur long X 67 mm wide X 36 mm deep, the elevator cab without stopping when the elevator door is closed. or 4.96 in. long X 2.64 in. wide X 1.42 unnecessarily for waiting hall calls. N The camera’s field of view must be in. deep). However, the system will Monitoring elevator cab volume considered. Based on a 2.1-m be most effective when the elevator consumption using an infrared-camera (6.8-ft.) mounting height, the ob- cab floor is in full view. system includes the following appli- served space inside the elevator The ideal position for ceiling- cation requirements: cab for a field of view equal to 54° mounted applications is in the center

Figure 1: ESPROS/VOL images showing different levels of elevator cab volume consumption (l-r): 15% full; 50% full; 75% full

74 | WWW.ELEVATOR-WORLD.COM | November 2008 of the cab with a full view of the ele- ble. The mounting location shown in of the elevator on the wall directly vator cab floor. Figures 2-5 were Figure 3 only partially monitors the above the elevator door. Figure 5 captured in an elevator with a floor elevator cab floor. In this case, that was captured in an elevator with a area of 1.2 m X 1.5 m (3.9 ft. X 4.9 ft.) part of the floor in the front of the floor area of 1.2 m X 1.5 m (3.9 ft. X at a mounting height of 2 m (6.5 ft.). cab is out of camera view. 4.9 ft.) at a mounting height of 2.1 m The crosshair shown in Figure 2 The mounting location indicated (6.8 ft.). The crosshair shown in Fig- shows the mounting position of the by the crosshair shown in Figure 4 ure 5 shows the mounting position camera in the ceiling with respect to affects system performance by dou- of the camera located on the wall the elevator cab floor. Camera images ble counting pixels, once for an ac- above elevator cab door. are slightly rectangular (i.e., not square) tual person or object and once for To mount the ESPROS/VOL, fasten as the view is larger for the housing the associated reflection in the mir- the mounting plate provided with the length than for the housing width. ror. As more passengers or objects device to the selected location in the Care should be taken to avoid un- enter the cab, the double counting elevator cab. Once the mounting plate favorable mounting locations. Figures effect becomes worse. has been secured, slide the ESPROS/ 3 and 4 show mounting locations The ideal position for wall- VOL housing onto the mounting that should be avoided when possi- mounted applications is in the middle plate as shown in Figure 6 below. Continued

Figure 2: Correct mounting location for ESPROS/VOL-V in ceiling Figure 3: Incorrect mounting location for ESPROS/VOL-V in ceiling of eleva- of elevator cab tor cab (0.5 m from back of elevator cab)

Figure 4: Incorrect mounting location for ESPROS/VOL-V in ceiling of eleva- Figure 5: Correct mounting location for ESPROS/VOL-A on wall of elevator tor cab near mirrored back wall cab above elevator door

Figure 6: Fastening the mounting plate and then sliding the ESPROS housing on to the mounting plate

November 2008 | ELEVATOR WORLD | 75 EW ECO-ISSUES: Continuing Education Continued

Device Connections lishing which threshold value should (green) is illuminated, the occupied A single 11-conductor cable, 2 m be used. Potentiometer P3 defines floor space in the elevator car is (8 ft.) in length, provides connections the recalibration time from 20 to 120 higher than the threshold value set for power, communication and relay seconds. When the camera image by potentiometer P1. When the Relay outputs from the ESPROS/VOL cam- remains constant for the recalibra- Out 2 LED (red) is illuminated, the era. Power connections consist of a tion time period, that image becomes elevator car is not empty. LEDs L1, 24 VDC and Common. Connections the stored reference image. This L2 and L3 (all green) provide diagnos- for communication to a computer allows environmental changes within tic information related to recalibra- are RS-232 receive (Rx) and transmit the elevator cab (e.g., a burned out tion. In particular, when LED L3 is (Tx) lines. These connections are light) to be taken into account. blinking, it indicates that the ESPROS/ used for communicating to the visu- The DIP switches are used to define VOL device is operating properly. alization software described later in additional recalibration parameters, Visualization Software this article. Relay outputs are avail- darkness mode and relay properties. Microsoft® Windows XP® or Vista® able that provide indication of: Darkness mode is used when the compatible software may be used to N When the user-configured threshold brightness of the elevator cab de- communicate status and current value has been reached (normally creases suddenly (e.g., the elevator configuration information from the open and normally closed contacts) cab lighting is turned off when the sensor using RS-232c communication. N When the elevator cab is occupied elevator is not in operation). When This is particularly useful for both (normally open and normally closed darkness mode is activated and the troubleshooting and initial configu- contacts) brightness in the cab suddenly de- ration. The software communicates to It is important to note that the relay creases, the camera no longer recal- the ESPROS/VOL device using the outputs should only be evaluated by ibrates the stored image. In this case, RS-232c communication conductors the elevator control system when: the relay output remains in the pre- (Rx, Tx and GND) available in the cable. N The elevator door is shut. darkness state, as determined If RS-232c is not available at the com- N The light in the elevator cab is on. through other DIP switch settings. puter, the RS-232 signals can be con- Configurable Parameters The darkness mode ceases when the verted to a universal serial bus signal Configuration of the ESPROS/VOL brightness inside the elevator cab re- using a conventional cable converter. is implemented using three poten- turns to near its previous value. Figure 8 shows several examples tiometers and one bank of digital Diagnostic Indicators of how the visualization software image processing (DIP) switches. The ESPROS/VOL features sev- may be used for configuration and Figure 7 shows the location of these eral diagnostic indicators for ease of troubleshooting of the ESPROS/VOL items. Potentiometer P1 configures troubleshooting. The yellow power camera system. The left picture shows the threshold value from 4% to 100%. LED indicates when power is present an ESPROS/VOL system in which no Potentiometer P2 is used to turn a on the device. If this LED is not illu- passengers are present. Note that the buzzer on or off when the current minated, check the power connec- occupancy is 0% and the Relay Out 1 occupancy is greater than the thresh- tions and ensure that power is pres- and Relay Out 2 are both inactive old value. This is helpful for estab- ent. When the Relay Out 1 LED (NC). The potentiometer values are also indicated (P1 = 64%; P2 = 0; and LED Yellow / Power P3 = 79 seconds). The middle picture LED Green L3 provides an example of a cab that is Service Connection Interface Relay Out 1 and LED Green LED Green L2 occupied, but has not yet reached the Relay Out 2 and LED Red LED Green L1 DIP Switches SW threshold set point. The potentiometer values have not changed, but now Relay Out 2 is active (NO). The right picture shows that the occupancy value has met/exceeded the threshold value. In this case, the potentiometer values have remained constant, but Relay Out 1 is active. This relay signal would be used to implement the bypass or express run signal in the elevator control system. Startup Procedure Potentiometer P1: Threshold Level Potentiometer P2: Buzzer ON/OFF After the ESPROS/VOL camera is Potentiometer P3: Recalibration Time mounted in accordance with your Figure 7: ESPROS/VOL indicators and configuration potentiometers/DIP switches 76 | WWW.ELEVATOR-WORLD.COM | November 2008 Figure 8: ESPROS/VOL visualization software tool screenshots application requirements, the initial the reference image based on its camera-based monitoring with the startup is straightforward. Begin by configuration settings (based on po- load-weighing system to provide a implementing the following steps: tentiometer P3 setting; factory de- clear picture of the current state of N Make the necessary cable connec- fault setting is 20 seconds). “fullness” in the elevator cab. tions for power, relay outputs and When the power to the ESPROS/ James O’Laughlin recently joined CEDES Corp. communication. VOL is interrupted, the elevator control of America in Minneapolis as a product marketing N Configure the DIP switches in ac- should ensure that the following has manager. He received his BSEE from Mankato cordance with your application occurred before utilizing signals from State University in 1988. He has specifically fo- requirements. the relay outputs of the ESPROS/VOL: cused on the integration of safety technologies in N N Ensure that elevator doors are The elevator door must be closed. industrial machinery over the past 10 years and N closed. The light in the elevator car must has been engaged in engineering, sales and mar- N Ensure that the lights are turned be on. keting roles within the industrial automation sec- on inside the elevator cab. The ESPROS/VOL has cycled tor for the past 20 years. N Ensure that the elevator cab is through the recalibration time. empty. Conclusions N Cycle power to ESPROS/VOL Optimal elevator performance has Learning-Reinforcement camera. and will continue to be a high prior- Questions N Wait five seconds for the internal ity for building and facility profes- Use the below learning-rein- power-up sequence to complete sionals. When an elevator cab is full forcement questions to study for and a reference image to be taken. but continually stops to service hall the Continuing Education Assess- At this point, the ESPROS/VOL calls, the unnecessary delays and in- ment Exam available online at camera is operational and you can convenience lead to unhappy cus- www.elevatorbooks.com or on configure parameters using the po- tomers, patients, tenants and more. page 149 of this issue. tentiometers. You may wish to con- Load-weighing systems and camera- N Which methods can be used to sider adjusting the occupancy thresh- based technologies can assist with improve efficiency of elevator old value with the help of the buzzer minimizing or eliminating this issue. systems during high-traffic peri- (potentiometer P2 set to a value ≥ 2). Camera-based monitoring pro- ods? When the buzzer is active, it will vides an intelligent solution to load- N sound when the ESPROS/VOL detects weighing systems. It can accurately Which benefits does camera- that the percentage of pixels that have account for non-passenger loads based volume consumption changed between the reference image that weigh significantly less than the monitoring offer compared to and the current image has met or ex- amount of space that would be occu- load-weighing monitor systems? N ceeded the configured threshold pied by people. Examples include What application requirements value. Once you have determined the wheelchairs, hospital gurneys and must be addressed for camera- occupancy threshold value (using luggage carts. That said, load-weigh- based volume consumption potentiometer P1), set the buzzer ing systems may need to fulfill other monitoring? configuration back to inactive (po- elevator performance requirements N How do you implement a cam- tentiometer P2 set to a value ≤1). (e.g., prevention of rollback) and can- era-based volume consumption In the event that power cannot be not always be eliminated from the monitoring system into an ex- cycled (i.e., turned off and then back elevator control system. When this is isting elevator cab? on), the ESPROS/VOL will recalibrate the case, the best solution uses both

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EW ECO-ISSUES: Continuing Education

ELEVATOR WORLD Continuing Education Assessment Examination Questions Instructions: N Read the article “Improving Elevator Performance by Monitoring Elevator Cab Volume” (page 73) and study the learning-reinforcement questions. N To receive one hour of continuing-education credit, answer the assessment examination questions found below online at www.elevatorbooks.com or fill out the ELEVATOR WORLD Continuing Education Reporting Form found over- leaf and submit by mail with payment. N Approved for Continuing Education by NAEC for CET and NAESAI for QEI.

1. Which of the following methods provides the most cost- 6. The recalibration time of the CEDES ESPROS/VOL cam- effective and efficient improvement for elevator applica- era-based volume consumption monitoring is the tions where non-passenger loads frequently occur? amount of time required: a. Destination-dispatch systems. a. For the camera relay output to return to its resting state. b. Camera-based volume consumption monitoring sys- b. For the camera image to remain constant before it tems. becomes the new reference image. c. For the elevator operation control to respond to the c. Load-weighing monitoring systems. camera output. d. Adding additional elevators. d. For the camera buzzer to start buzzing after the camera image reaches the user-defined threshold. 2. What term is used to describe an “express run” condition in which the elevator-operation control ignores hall calls 7. The CEDES ESPROS/VOL camera system supports commu- when the elevator cab is full? nication from the camera to the visualization software via: a. Circumvent. a. CAN protocol. b. Circumnavigate. b. RS-232. c. Bypass. c. RS-422. d. Diversion. d. HART protocol.

3. The threshold value of the CEDES ESPROS/VOL camera- 8. When troubleshooting a CEDES ESPROS/VOL camera based volume consumption monitoring compares a system installation, and the yellow LED is not illuminated, you should: stored reference image to the current camera image. The a. Check to ensure that there is sufficient infrared light number of pixels that are compared is: available inside the elevator cab. a. 10,000. b. Make sure that 24-VDC power is connected to the device. b. 50,000. c. Verify that RS-232 communication is occurring between c. 75,000. the camera and a computer that has the visualization d. More than 100,000. software. d. Make sure the image inside the cab does not change 4. The most efficient and consistent light source that for the defined recalibration time. should be used with infrared cameras located inside an elevator cab is: 9. What are used on the CESES ESPROS/VOL camera system a. Fluorescent lighting. to define additional recalibration parameters, darkness b. Neon lighting. mode and relay properties? c. Halogen lighting. a. DIP switches. b. Potentiometers. d. Direct sunlight. c. Banks. d. Transmit lines. 5. When mounting a camera-based volume consumption monitoring system, it is important that the camera’s 10. Which is NOT a method that can be used to minimize image (camera view) is focused on the: the instance of full cabs responding to hall calls? a. Elevator cab floor. a. Increasing the number of elevators in service. b. Elevator cab back wall. b. Destination-dispatch systems. c. Elevator cab doors. c. Emergency-operations systems. d. Elevator cab ceiling. d. Load-weighing monitoring systems.

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