Automatic access control to Safety Category III animal enclosures in zoos

Status:

completed 12/2019

Aims:

Fatal accidents have occurred in the past in a number of zoos during work involving tigers. Safety Category III animal enclosures are designed to prevent unintended contact with particularly dangerous animals, such as great apes, bears, tigers and other big cats, spotted hyenas. However, safe access to dangerous areas is dependent entirely on organisational measures.

This means that before they access an enclosure, staff must ensure that it is safe to do so. The following weak spots in particular have been identified: enclosures that are large or not easily observable, large numbers of animals e.g. in the great apes territory, exposure of the employee to mental stress, for example in the form of monotony, work pressure, traumatic events, organization ( e.g. unclear agreements or too many people with access entitlement). These factors may result in staff misjudging situations and in turn in errors occurring which in a worst-case scenario may have fatal consequences.

The objective is for an access monitoring system to be implemented that functions automatically and allows staff to access an enclosure only when it is safe for them to do so. For this purpose, safe sensors, for example employing Radio Frequency Identification (RFID), are to be selected and combined (sensor fusion) and safe access is to be enabled by means of a safe control system.

Activities/Methods:

In the first phase, the work processes, ambient conditions and animal behaviour were studied with regard to the suitability of a number of sensor and actuator technologies. Searches were then conducted to determine whether the technologies currently available on the market could be used for attainment of the objective referred to above. The project was divided into two parts:

1. Access monitoring
For this part, a safety concept was developed which permits access to an enclosure only if the adjacent guillotine doors (for entry by animals) are closed and interlocked against re-opening whilst access by persons to the enclosure is still possible. Sensors, actuators and control components suitable for this purpose were identified. The results were summarized in an information paper produced by the VBG and serving as guidance for zoos.

2. Animal detection
A market survey was first conducted to determine to what extent the sensor technologies and safety concepts commonly used in machine guarding are suitable for this application. Since the technologies currently available did not appear suitable, new monitoring concepts were developed.

With the support of external partners (Assion electronic GmbH, TH Köln), the suitability of these concepts in principle was tested, and initial functional models were developed. These safety systems were developed with funding by a research grant from the German Federal Ministry of Economics and Technology (BMWi), which was initiated by the project.

Results:

Basic requirements were agreed for locking systems in animal enclosures. These locking systems are based on safety concepts commonly used in machine construction, and consist of guard locking, position switches and safety control systems. They prevent keepers from entering animal enclosures whilst the adjacent animal entries are not closed. The results were published in the VBG information paper “Requirements for interlock systems in Level III enclosures – Tips for the introduction of an extended safety concept”.

Two new systems were developed with research funding from the BMWi. At present they are considered suitable in principle for implementing reliable animal detection. The first system is a transponder system employing newly developed RFID transponders. These can be implanted in the animals, and also have a greater read range than the commercially available transponders. The second system is camera-based and enables the animals to be detected and identified by their fur markings. The location of the animals within the enclosure can thus be determined and used for access protection.

Further studies into the suitability of the two systems are however necessary, since as yet these concepts have been implemented only in purely functional terms and are not designed as safe systems for occupational safety and health purposes. This would require the integration of error detection measures such as plausibility checks, self-tests, etc. The studies are planned as part of a follow-on project, the objective of which is to ensure both the evaluation and the engineered safety of the newly developed systems.

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