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Mitsubishi elevator group control systems

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This page discusses the various group control (dispatching) systems developed by Mitsubishi Electric for their elevators.

Auto Select-O-Pattern Auto (ASP-A)[]

Main article: Mitsubishi Auto Select-O-Pattern Auto

Optimum Service System (OS-System) series[]

OS-System 700 (OS-700)[]

The OS-System 700 was a group control system developed by Mitsubishi in 1971[1] and introduced in market in 1972[2]. as the successor to the Auto-Select-O-Pattern Auto series of group control systems. The first installation of a Mitsubishi elevator with the OS-System 700 group control system was in 1973.[3]

It was succeeded by OS-System 750.

OS-System 750[]

Flagship elevator group control system, developed as the successor to OS-System 700. Also known as OS-750[4].

OS-System 75 (OS-75)[]

The OS-System 75 group control system, introduced in 1976[5] as a lower-end option to OS-System 700. It was developed as the successor to the ASP-A group control system, which had been offered as a lower-end option previously[1]. It is based on the OS-System 700.

Demand bands[]

Like the OS-System 700, the serviced floors in OS-System 75 are grouped into multiple so-called "demand bands"[1]. When a hall call is placed, an elevator car is assigned to the corresponding "demand band". Once the car has finished responding to the calls allocated within the respective band, it waits at a vantage position of its choice until it is assigned another call. It also uses a unique "interactive simulator" to analyze data under different traffic conditions.

The adoption of the assignment method eliminates any wasteful actions, such as waiting to adjust departure intervals or having to travel to a departure floor even if there are no calls. It also allows for decentralized car allocation depending on the distribution of floor traffic, thus improving operational efficiency as well as shortening waiting times across all conditions, with Mitsubishi Electric claiming a reduction of 10-20% in average waiting times, as well as a reduction in long waiting times (>=50s) of 30-50% over the ASP-A group control system[1].

OS-System 75E[]

Also possibly known as OS-75E. It was known to be used on the Mitsubishi MP high-speed elevator model[6][7].

OS-System 2100[]

Also known as OS-2100[4][8], it was introduced in 1979 as the successor to OS-System 750. It is the first group control system to be based on microcomputer technology[9].

OS-System 2100C[]

Successor to OS-System 2100, OS-System 2100C was introduced in 1982[5], and was also known as OS-2100C[10]. It is the last in the OS series of group control systems, having been superseded by Mitsubishi's AI series of group control systems in the late 1980s.

The OS-System 2100C was introduced with the Mitsubishi ACCEL model[11], introduced in 1982, and was also used on its export counterpart, the MP-III[12]. The ACCEL-VF[13], the successor to ACCEL, as well as its export counterpart MP-VF also used the OS-2100C system as well.

Artificial Intelligence (AI) series[]

AI-2100[]

DTT Mitsubishi GPM

Set of 4 Mitsubishi GPM elevators with the AI-2100 group control system.

The AI-2100 group control system was launched in 1988[2] as the successor of OS-System 2100C. It is the first in the AI series of group control systems, which was a successor to the Optimum Service System series of group control systems. The AI-2100 group control system introduces an "expert system" based on fuzzy logic as well as other intelligent group control system features for more efficient operation and improved passenger comfort.

The AI-2100 was introduced with the Japanese-exclusive Mitsubishi ACCEL-AI custom type elevator model, and was also used on its export counterpart, the Mitsubishi GPM, as well.

Expert system and fuzzy logic[]

An "expert" group supervisory control system utilizes the past and present knowledge of the floor traffic to shorten waiting times as well as simplify boarding and alighting under varied traffic conditions.

Traffic data employed in an expert system is quite fragmented and involves quite a lot of fuzzy logic (i.e. logic with multiple degrees of truth outcomes; as opposed to boolean logic, where the outcomes can be either true or false), which makes evaluating it quite a complicated task with traditional hardware and software. The AI-2100 group control system thus employs two high-performance 32-bit microprocessors that allow the expert system in the group controller to process this scale of data.

The expert system employs a fuzzy-rule base which expresses elevator group control principles in the form of "off-line" and "on-line" IF-THEN rules:

  • On-line rules: rules applied when a hall call is registered, such as assigning of elevator cars to calls in a way that prevents multiple cars from travelling in groups so as to meet the demands of floor traffic.
  • Off-line rules: rules applied at all times regardless of the occurrence of hall calls, such as the number of cars to be allocated to floors with higher traffic during peak periods (up/down peak), and the floors at which elevators are to be parked when there are no hall calls to be answered to.

The off-line rules determine when to apply the on-line rules during different time periods. When a hall call is registered, the group control system employs fuzzy logic to determine which on-line rule is the most appropriate for the current traffic situation. These rule bases are pre-programmed by Mitsubishi into the group controller on the basis of several simulated traffic flow scenarios.

The implementation of the expert system and fuzzy logic in the group control system reduces the average waiting time and percentage of long wait times (>= 60s) compared to a conventional group control system, with Mitsubishi Electric claiming a 15% reduction in average wait times and an almost 50% reduction in the percentage of long wait times.

Information Network[]

A character display, placed both in the elevator lobby as well as in the elevator car, acts as an informational display that informs users of the elevators' running status. The hall display uses three-color LEDs and the car display a monochrome green vacuum fluorescent display. Emergency messages, if any, supersede any other messages, with multiple emergency messages being shown in the order of their priority.

Waiting-time Display System[]

A first of its kind, this system employs a graphic LED-based hall lantern and shows the estimated time until an elevator arrives in response to a hall call. When a hall call is placed, the hall lantern of the elevator that would service the hall call lights up (see hall call prediction), showing the direction of the call (green for up, red for down), as well as the waiting time represented by an hourglass, with the "sand" in the hourglass trickling down as the time passes. The lantern flashes when the elevator arrives, with the last couple of "bits" of the sand flowing down as the doors open.

Destination-Floor Registration System[]

Not to be confused with Hitachi FIBEE, which is also known as Hitachi Destination Floor Reservation System (DFRS). To prevent confusion between the two, Mitsubishi's system will be referred to as DRS.


The Destination-Floor Registration System (DRS) employs a hall operating panel where passengers can select their destination. The AI-2100 group control system then uses this information to optimize the assignment of elevator cars. If the system does not detect any passengers entering the car (via the safety beam), the destination selected on the hall station will not be registered, thus preventing nuisance calls.

A lot of this behavior is quite similar to Mitsubishi's own DOAS system introduced later, which employed pre-programmed button panels. That said, DRS does not seem to group passengers by destination - it does not allocate passengers to a specific car based on destination, rather it allocates a single elevator car for all passengers in each travelling direction. Hence, unlike DOAS, DRS is not a form of destination dispatch; rather, it can be thought of like a fancier version of hall call prediction.

Hall congestion-monitoring system[]

The AI-2100 system employs a video camera installed in the ceiling above the elevator lobby. Video captured from the camera is compared against a memory-stored "background" image, by employing digital video processing, which is used to determine the level of congestion at each floor. Using this information, the group control system prioritizes car assignment to floors with higher levels of congestion, as well as ensuring fully loaded cars bypass any waiting passengers.

Other intelligent group control features:[]

  • Voice guidance system: An automated voice makes guidance announcements (floor and direction announcements), as well as any emergency announcements (fire, earthquake, power outage etc.).
  • Secret call system: Restricted floors are locked using an access code or magstripe card.
  • Remote control system: A telephone system (most likely a telephone modem) allows each car to receive control commands from within the building or an external location.
  • Supervisory system: A CRT-based IDU (integrated display unit) allows for monitoring and controlling the entire elevator system. An operator can interface with the IDU by means of a keyboard or light pen.

AI-2100N[]

BTH GPM-III elevators

Set of 4 Mitsubishi GPM-III elevators using the AI-2100N group control system.

The AI-2100N group control system was introduced sometime around 1996 as the successor to AI-2100. It is the first Mitsubishi elevator group control system to implement neural networks[14]. It had introduced the following group control features:

Distinction of Traffic Flow with Neural Networks[]

The AI-2100N group control system utilizes neural networks to identify various traffic patterns in real time, enabling it to distinguish the number of passengers boarding and exiting the elevator cars. The AI-2100N group control system features a learning module that records traffic patterns, enabling it to provide an optimal operating pattern that constantly adapts to respond more effectively and efficiently to changing traffic flows.

Car allocation tuning[]

To improve the average waiting times on each floor in the building, the AI-2100N group control system applies an algorithm to control the number of elevator cars allocated to crowded floors during peak periods (such for instance, in an office building, incoming, lunchtime and outgoing traffic).

As compared with the previous generation of group control systems, the AI-2100N brings improved elevator efficiency and reduced waiting times, thus improving the passenger experience. Mitsubishi Electric claims a 10% reduction in average waiting times as well as a 20% reduction in long wait times (>60s) over the AI-2100 group control system, and a 42% reduction in average waiting times over the OS-2100C group control system.

The AI-2100N group control system was mainly used on the Mitsubishi GPS-III and GPM-III elevators (late 1990s models).

ΣAI series[]

ΣAI-2200[]

Enhanced group control system with neural network and Dynamic Rule-Set Optimizer[10], introduced around the early 2000s as the successor to AI-2100N. Superseded by ΣAI-2200C.

It is mainly used on early Mitsubishi NexWay (2000s, except Series-AW Hospital). Later model (2000s-2011) GPS-III and GPM-III elevators also used ΣAI-2200.

In addition to the features the AI-2100N group control system has, such as using neural networks to distinguish traffic flows and car allocation tuning, the ΣAI-2200 group control system introduces the following group control features:

Dynamic rule-set optimizer[]

Using neural networks, the ΣAI-2200 group control system can now predict floor traffic a couple of minutes ahead of time. Based on this predicted traffic, real-time simulations are performed and the optimal rule-set is selected. Based on the rule set selected, the allocation of elevator cars is performed.

Destination Oriented Allocation System[]

Main article: Mitsubishi Destination Oriented Allocation System

The ΣAI-2200 group control system also introduces Mitsubishi's destination dispatch system, known as the Destination Oriented Allocation System (DOAS, originally known as Destination Oriented Prediction System[15]). In this iteration of the system, a passenger presses the desired floor button on the hall operating panel (similar to DRS in AI-2100), and the car allocated to the hall call is indicated on a display next to the corresponding floor button[15].

ΣAI-2200C[]

GT Mitsubishi NEXIEZ DOAS

Set of 4 Mitsubishi NEXIEZ-MR elevators with DOAS, using the ΣAI-2200C group control system.

The ΣAI-2200C group control system was introduced by Mitsubishi Electric sometime around the late 2000s as the is the successor of the ΣAI-2200 group control system. It is the current flagship group control system offered by Mitsubishi for their elevators.

The ΣAI-2200C uses various factors to allocate the most optimal elevator car to a hall call, such as:

  • Waiting time from a particular hall call or an increase in the overall waiting time
  • Expected travel time
  • Full load bypass, or when an elevator car bypasses a hall call owing to a full load
  • Long wait times caused by future calls
  • Energy consumption.

It introduces the following group control features:

Cooperative optimization assignment[]

When a hall call is registered, an algorithm predicts a near-future call that could require a long wait. The best elevator car to be assigned to the hall call placed is determined after evaluating the registered hall call and the forecasted hall call.

This reduces long wait times and improves average waiting times for all passengers.

Energy-saving Operation — Allocation Control (ESO-W)[]

The ΣAI-2200C group control system selects the elevator in the group that best balances operational efficiency and energy consumption. During peak hours, the system prioritizes operational efficiency over energy consumption and vice versa during non-peak hours.

This system works on the principle that car allocation based on maximum operational efficiency does not necessarily mean energy efficiency. For instance, an elevator car is more energy-efficient when travelling up with a light load, or down with a heavy load (as the traction machine does not have to exert as much power in either case to move the elevator car). On this basis, if multiple elevator cars have the same travelling distance, the system chooses the car that uses the least amount of energy. This feature allows for reduced power consumption, with Mitsubishi Electric claiming a 10% reduction in power consumption over the ΣAI-2200 group control system.

The ΣAI-2200C also has Mitsubishi's Destination Oriented Allocation System (DOAS) destination dispatch system available as an option. ΣAI-2200C's iteration of DOAS is more similar to other destination dispatch systems, with keypad floor selection as opposed to a pre-programmed hall station.

The ΣAI-2200C group control system is used on the following Mitsubishi elevator models:

Notes and references[]

  1. ↑ 1.0 1.1 1.2 1.3 Mitsubishi Electric Corporation, “Elevators and Escalators,” Mitsubishi Denki Giho, vol. 51, no. 1, pp. 69–71, Jan. 1977, Available: https://www.giho.mitsubishielectric.co.jp/giho/pdf/1977/7701.pdf
  2. ↑ 2.0 2.1 Elevator & Escalators - MITSUBISHI ELECTRIC
  3. ↑ Toshiaki Ishii, Hidenori Watanabe, Takeo Kanematsu, Yasuhiko Ozawa, and Kazushi Kunii, “The O.S. System-700, a New Group Supervisory System for Elevators,” Mitsubishi Denki Giho, vol. 48, no. 12, pp. 1357–1359, Dec. 1974, Available: https://www.giho.mitsubishielectric.co.jp/giho/pdf/1974/7412.pdf
  4. ↑ 4.0 4.1 Yoshitaka Matsukura and Eiki Watanabe, “Progress in Elevator and Escalator Engineering,” Mitsubishi Denki Giho, vol. 61, no. 11, pp. 2–4, Nov. 1987, Available: https://www.giho.mitsubishielectric.co.jp/giho/pdf/1987/8711.pdf
  5. ↑ 5.0 5.1 https://www.giho.mitsubishielectric.co.jp/giho/pdf/2012/1208109.pdf
  6. ↑ Mitsubishi Electric Corporation, “Export Elevators,” Mitsubishi Denki Giho, vol. 54, no. 1, p. 84, Jan. 1980, Available: https://www.giho.mitsubishielectric.co.jp/giho/pdf/1980/8001.pdf
  7. ↑ Kenzo Funahashi, “Passenger Elevators For Export,” Mitsubishi Electric ADVANCE, vol. 13, pp. 7–8, Sep. 1980.
  8. ↑ https://www.giho.mitsubishielectric.co.jp/giho/pdf/1983/8311.pdf
  9. ↑ Tsuyoshi Sato, Toshiyuki Kamohara, Ryoji Takahashi, Yoichi Ichioka, and Toshiaki Ishii, “An All-Solid-State Control System for High-Grade Passenger Elevators,” Mitsubishi Denki Giho, vol. 53, no. 3, pp. 187–191, Mar. 1979, Available: https://www.giho.mitsubishielectric.co.jp/giho/pdf/1979/7903.pdf
  10. ↑ 10.0 10.1 https://co.mitsubishielectric.com/es/products-solutions/building/pdf/catalogo_sistema_de_control_de_grupo_ai-2200c.pdf
  11. ↑ Yasukazu Umeda, Masashi Yonemoto, Ryoji Takahashi, Mineo Seiriki, and Katsumi Makino, “The ‘Accel’ Series of Made-to-Order Elevators,” Mitsubishi Denki Giho, vol. 56, no. 9, pp. 53–57, Sep. 1982, Available: https://www.giho.mitsubishielectric.co.jp/giho/pdf/1982/8209.pdf
  12. ↑ Haruhide Inage, Shigesada Kawai, Masashi Yonemoto, and Mineo Seiriki, “Export Models of All-Computer-Controlled Passenger Elevators (ACCELs),” Mitsubishi Denki Giho, vol. 57, no. 11, pp. 10–14, 1983, Available: https://www.giho.mitsubishielectric.co.jp/giho/pdf/1983/8311.pdf
  13. ↑ Yoichi Ichioka, Isao Sasao, Shintaro Tsuji, Hideyo Ujihara, and Kenji Yoshida, “The Options High-Performance Passenger Elevators for Intelligent-Buildings,” Mitsubishi Denki Giho, vol. 61, no. 11, pp. 21–26, Nov. 1987, Available: https://www.giho.mitsubishielectric.co.jp/giho/pdf/1987/8711.pdf
  14. ↑ https://www.mitsubishielevator.com/uploads/files/pdf/elevators/high-speed/Series_GPM-III_Brochure.pdf
  15. ↑ 15.0 15.1 https://web.archive.org/web/20050320044028/http://www.mitsubishi-elevator.com/design/ele/gpm3/gpm3_art.htm
  16. ↑ https://elevbrochurearchive.wordpress.com/wp-content/uploads/2018/07/nexway-high-speed.pdf
  17. ↑ https://www.mebs.com/resources/downloads/pdf/gn011.pdf
  18. ↑ https://elevbrochurearchive.wordpress.com/wp-content/uploads/2018/07/nextway-modernization.pdf
  19. ↑ https://elevbrochurearchive.wordpress.com/wp-content/uploads/2018/07/elemotion-2015-edition.pdf
  20. ↑ https://www.mitsubishielevator.co.th/2018/assets/images/modernization/brochure_elemotion.pdf

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