Due to their flexibility, automated guided vehicle systems (AGVs) are one of the most important supply solutions in hospital supply logistics, writes Michael Dold, strategic industry manager of industrial vehicles, Global Industry Center Logistics Automation – Transport Logistics, SICK.
Increasing digitalisation, with its ability to make the complex networking of logistic processes transparent and provide a wide range of valuable data, sociodemographic development as well as the acute lack of specialists in the care sector that will not subside in the foreseeable future will make AGVs even more important in the future. Innovative and high-performance sensor technology for localisation and navigation, for environment recognition and collision avoidance, for fleet management and material tracking as well as diagnostics of individual vehicles offer the potential for further improving the autonomy and efficiency of AGV systems in health care.
Such an entity commissions manufacturers of AGVs and entire AGV systems, which are usually either general contractors for the hospital’s entire logistics processes or, can purchase all the sensor technology from SICK as an easy-to-integrate complete solution without interface risks. The company is considered the provider with the widest range of products and solutions for AGV systems, partially-automated industrial trucks and mobile platforms. The complete solutions are integrated systems which cover all aspects of localisation and collision avoidance, personal safety and the handling and identification of load carriers typical for hospitals – usually stainless steel rolling containers for various purposes. The complete systems are increasingly focused on the use of sensor data and system information, which display the physical transport processes digitally when integrating AGV systems into the information and merchandise management systems of hospitals.
Personal safety and collision avoidance
While, in the past, the use of automated guided vehicles in hospitals was often limited to separate, non-public areas, AGV systems are now increasingly being used in publicly-accessible areas. In particular, the transport of small parts is done more and more by more compact, agile and flexible vehicles and mobile platforms. When it comes to traffic technology, this means that these AGVs are more often moving in the same environment as people. Another aspect is significant here: While the hospital staff is used to automated guided vehicles and is trained on dealing with them by the hospital as the operating entity, this is not true for patients, visitors, children and other external parties who could behave differently or unexpectedly. This results in special requirements on the safe operation of AGV systems and the use of safety-certified sensor and control components. The manufacturer must perform its risk analysis for every project, and the operating entity must also do this for its use as well as observe the relevant C-standard type. The safety system must be configured individually for each vehicle type and each clinical working environment.
Safety laser scanners from the S300, S300 Mini or microScan3 product families with individually programmable protective fields detect persons and obstacles in hallways and routes and slow movement down to a safe stop. At the same time, safe encoders like the DFS60S Pro and safe non-contact end switches monitor the driving speed as well as the current and maximum permissible steering angle of the vehicles. They are coordinated by the modular Flexi Soft safety control, which fuses the signals of the safe encoders, 2D LiDAR sensors, end switches and emergency stop pushbuttons, thereby allowing for smart, situation-dependent person recognition. As a supplement to the certified safety system, 3D LiDAR sensors such as the MRS1000 multi-layer scanner, which actively measures simultaneously on several levels, as well as the 3D snapshot detection sensors of the Visionary-T product family can be used to improve collision avoidance further. Thanks to their high resolution, they are also able to detect thin objects such as canes, walkers, wheelchairs, infusion stands or device carts.
Localisation and navigation
Current numbers show the extent of the intralogistical challenges in hospitals. The frontrunner with patients (in case numbers, nearly 137,000) and employed doctors (1,650) is the Charité in Berlin, which is alone at the top with just over 3,000 beds. If you put all the hospitals together, they have on average 245 beds. Based on the total number or nearly two million patients in 2017, this means that several thousand patients are treated per hospital in Germany. In various areas of a hospital, this requires a wide range of different material flows in which vehicles will move even more in public areas in the future. They will share hallways and elevators with doctors, nurses and caregivers, but also with patients and visitors. Depending on the required material flow, the vehicles either have a fixed delivery and receipt address in the hospital or they move in a complex network of different starting points and destinations. In order to best utilise transport capacities and routes and ensure the punctual supply and clearing of individual areas essential in many cases, reliable localisation and route-optimised navigation of automated guided vehicles are required.
The SICK safety laser scanners with 2D LiDAR technology, in addition to their actual purpose as a person recognition system, are also used to measure room contours and artificial landmarks (e.g. reflectors). From the measured values of the sensor, the current contour data is compared with the reference data saved in a map in the navigation computer and the current vehicle position is calculated from this. The continuous position information is sent from the AGV on-board computer to the central master controller via WLAN and then used for navigation at the same time. Alternatively, or only in sub-areas in addition to increasing local accuracy and resistance, optical or magnetic line guidance sensors of the OLS or MLS product families from SICK can also be used for localisation. The GLS smart grid localisation sensor is perfectly suited for verifying the absolute position in the material flow. Using the identification of DataMatrix codes at points of decision along the route, this sensor also enables automated correction of the vehicle position not only in the x- and y-position, but also with regards to orientation.
Identification of means of transport: The foundation for hospital 4.0
Standard and special containers, carts, and crates are the means of transport most commonly used in AGV systems in hospitals. They differ in their use and are often only permitted for certain types of transport or application in defined areas. They are either currently in use, are being cleaned, or are waiting in the container storage space for their next order. Unique labelling of the containers is required for the container management system to be able to administer and plan the means of transport and to ensure prompt and gap-free tracking in the central master controller (track and trace). Bar code technology is well-suited for this task. It allows containers which are labelled with such optional codes to be quickly and reliably identified both with reading devices on the AGV system and hand-held scanners. RFID systems are perfectly suited for labelling containers which must be cleaned and disinfected regularly or for which the information, for example on the current state of cleaning, is to be updated directly on the object. Due to the identification of all containers in the hospital, they are visible at all times in the AGV system master controller. In the spirit of hospital 4.0, their physical activities are networked transparently with the data in the control level so that the digitalised processes of hospital logistics always provide a congruent and up-to-date representation of the actual flow of transport and goods. In turn, this makes it possible to provide transport aids optimally: The right container on-time for the respective type of transport, no use of defective or dirty transport aids or only scheduling for runs in permitted areas, for example in hygiene-sensitive departments.
AGV systems in hospitals: From transport to service solution
Cost pressure, increases in efficiency, and digitalisation are also major drivers of automation in hospitals. For technical and economic reasons, AGV systems will, therefore, be playing an increasingly significant role in ensuring high logistics availability in hospitals at all times. Particular emphasis is placed on their importance due to the sociodemographic shift in society, the lack of specialists as well as the development of automated guided vehicle into mobile service platforms which interact with service staff and patients. Mobile robots which bring food to hospital beds and then pick up the trays and provide other services will make it possible for hospital employees to concentrate on their core care expertise. The advancement of vehicles is already heading in this direction – for example in the form of camera-based gesture control with which the vehicles are programmed and can be operated intuitively by the increasingly multilingual care staff and patients. Smart sensors will play a significant role in these developments.