Transport automation column vol.6
Automating inter-floor transportation through collaboration between AMR and elevators | Case studies and key points for implementation
table of contents
Introduction
Compared to overseas factories, Japanese factories often use multi-story buildings to make the most of their limited land area.
It is not uncommon for floors to be divided by process, with goods arriving on the first floor, assembly on the second floor, inspection on the third floor, and shipping on the first floor.
In such an environment, workers must go to the elevator, operate it, and then return to their original task in order to transport carts loaded with work-in-progress or parts to another floor, a process that must be repeated many times throughout the day.
"I have to go back and forth every time just to hand it over to the next process" or "I realize that a lot of time is being spent transporting it" -- many on-site managers and administrators have these concerns.
In recent years, autonomous driving technology for AMRs has evolved, and efforts to automate the process of transporting goods across floors are becoming more widespread.
AMRs can autonomously call elevators, move to the destination floor, and deliver packages to the next work area - we are now in an era where multi-floor transportation, which was once performed by humans, can be automated.
Already, an increasing number of workplaces are introducing elevator-linked AMRs to improve productivity and alleviate labor shortages.
This article provides an easy-to-understand explanation for production line managers and production technology personnel of the effects seen from implementation cases and the technical points that should be kept in mind when considering implementation.
Case study of an automated inter-floor transport system using AMR
Here we will introduce two examples: one where the system was introduced in conjunction with the start of operations at a new factory, and one where the system was introduced at an existing factory.
Case 1: Automation solution for inter-floor transportation of parts and finished products
IDEC Factory Solutions Co., Ltd. has built a new three-story factory for harness processing and control panel manufacturing.
The first floor consists of a logistics area and a manufacturing area for large control devices, the second floor is a manufacturing line for small devices such as control modules, and the third floor is a work area mainly for wire harness processing.
Because the processes are divided into different levels like this, there is a daily need to transport parts and materials that arrive on the first floor to the upper floors, and then return the assembled finished products to the first floor.
To automate these transportation tasks, we built an AMR system that automatically calls elevators and transports carts between floors.
The following five points were important when building the system.
Key Points
Top module development (cart docking design)
We designed a new cart that can be loaded onto the elevator, and then designed and developed a cart docking attachment (top module) that can be attached to the top of the AMR so that it can automatically dock with the cart and be transported.
Tablet UI for ease of use
Even an excellent system will not be effective if it cannot be operated intuitively by on-site workers. Tablets are placed on each floor so that AMRs can be called with the push of a button. Call instructions are sent to the AMR via wireless communication (Wi-Fi).
Elevator external control (DI/DO modification)
Since most commercial elevators do not come equipped with an external control interface as standard, we worked with the manufacturer to add DI/DO (digital input/output) to the control panel, allowing us to modify the elevator so that it can be signal-controlled from an external device (AMR control panel).
Design and implementation of elevator linkage control panel
We defined a standard communication sequence with the elevator and built a system between the AMR, control panel, and elevator control panel via a linked control panel that we designed and manufactured in-house.The AMR sends instructions wirelessly to the control panel, and the control panel outputs a signal to call the elevator, allowing the elevator to be used automatically.
Safety design for AMR exclusive operation
When an AMR and a person are in an elevator together, there is no escape route in the confined space, so there is a risk of the person being pinched or hit by the AMR due to sudden braking or rotation, or cargo shifting. Therefore, we have implemented an "AMR Occupancy Mode (our proprietary control)" that disables the call signal for people while the AMR is using the elevator, ensuring safety.
By introducing this system, we were able to allocate the man-hours of one person that previously had to be allocated to transportation work to value-added tasks such as assembly.
Case 2: Automated material transport solution between floors using existing carts
The second example is a case where inter-floor transportation was automated while making use of the existing factory and existing carts almost as they were.
In this case, the food manufacturer's factory had a material storage area and an area for temporarily storing materials to be used on the day on separate floors, and carts loaded with materials had to be manually transported at the start and end of work.
To improve work efficiency, it was originally desirable to move materials outside of business hours, but due to issues such as labor shortages and reducing the burden on workers, there were limitations to manual transportation.As a result, it was decided to introduce an automated system for inter-floor transportation that linked elevators and AMRs.
The main points of this case study are as follows:
Key Points
Modification of existing bogies (towing attachment)
We modified an existing cart so that it could be towed by an AMR. A major benefit is that there is no need to switch to a new cart, which reduces implementation costs. The towing attachment was designed by our company, with specifications optimized for on-site operations.
Elevator modification and linkage control panel
As with the first example, we modified the system to enable external control using digital I/O signals, and created a system that allows AMRs to automatically call and board/disembark according to their assigned tasks via a linking control panel. This makes it possible to transport between floors without human intervention.
Switching transport patterns (normal/busy periods)
In response to customer requests, we have developed a program that allows you to switch between transport patterns for normal and busy periods. Switching can be done easily from a tablet, reducing operational hassle and allowing you to flexibly respond to on-site conditions.
With the introduction of this system, it has become possible to automatically transport carts not only at the start and end of work, but also at necessary times during the day. As a result, almost all of the time that workers previously spent on transportation can now be used for their primary duties, greatly contributing to improved productivity.
The "SIer's perspective" for successful implementation
To build an inter-floor transport system that links AMRs and elevators, it is not enough for the AMRs to simply be able to move; comprehensive knowledge across multiple technical fields is required, including mechanical design, control, communications, safety, and linking with higher-level systems.
Here we will introduce some of the important points.
Technical understanding of top modules
First, it is important to understand the technology behind the top module that will be installed on the AMR. Because the specifications and transport methods of carts vary greatly between factories, it is necessary to design optimally for each site, including the cart docking method, towing method, load conditions, and positioning method.
System integration design for operational efficiency
Furthermore, when multiple AMRs are operated, efficiency cannot be achieved through the operation of each AMR alone. A mechanism for automatically generating and allocating transport tasks in conjunction with operation management and production management systems is essential. Transport across floors in particular requires logic that takes into account dependencies and priority control between tasks, and stable operation can only be achieved by properly designing these.
Wireless design and on-site verification within the factory
Because wireless communication is a prerequisite for linking with elevators, the quality of the factory network is directly linked to the stability of the entire system. The metal structure inside elevators makes it easy for radio waves to weaken, and RSSI can fluctuate significantly when moving between floors. Furthermore, wireless design and on-site testing that take into account the specific radio wave environment of a factory, such as the timing of access point switching and the occurrence of radio wave shadows, are essential.
Control design for linked control panels
The design of the linking control panel that acts as the intermediary between the AMR and elevator control panel is also extremely important. In addition to signal linking using DI/DO, control logic that combines safety and reliability is required, including interlock processing, timeout processing, and operation sequence design for each floor. Furthermore, when linking with peripheral equipment such as automatic doors and gates, a control design that takes into account the entire operating environment, including interlocks between equipment and intrusion detection, is required.
Risk assessment and safety measures
When AMRs travel in the same areas as people, risk assessments based on international safety standards such as ISO 3691-4 are essential. Safety and control are particularly important considerations when linking with elevators. The first decision to be made is whether the elevator will be used exclusively for AMRs or for shared use with people. If it is used for shared use, additional safety measures are required, such as introducing an AMR-only mode to prevent people from riding together.
Because these technical elements are intricately interrelated, outsourcing the AMR, elevator, and peripheral equipment to different manufacturers often results in complicated specification adjustments and significantly extended start-up times.In light of this, it is extremely important to have a system integrator that can consistently design mechanisms, controls, communications, safety, and system integration while understanding on-site operations.
Conclusion
Automating inter-floor transportation by combining AMRs and elevators is an effective way to eliminate bottlenecks between processes that previously required manual labor and significantly improve productivity throughout the factory. The effects are particularly pronounced in factories with multi-story structures, greatly contributing not only to improved production efficiency but also to a reduction in worker workload.
IDEC Factory Solutions provides comprehensive support for the processes required for automating inter-floor transport, from system integration utilizing existing equipment, design and production of top modules and dedicated jigs, control panel development, wireless network design, and compliance with safety standards.
Please feel free to consult with us from the initial consideration stage about what kind of automation is possible at your site and where you should start. We will propose the best solution for your site.
