Supplying power to AGVs and AMRs in a cleanroom
The market for Automated Guided Vehicles and autonomous mobile robots for the process industry is growing continuously. In semiconductor production, pharmaceuticals or medical technology robots can efficiently automate material transport in sensitive production environments. But in higher ISO cleanroom classes in particular, the installation of the systems has generally been time-consuming and expensive because of the introduction of particles during mechanical power supply. Wiferion explains how this can be overcome by inductive charging systems.
The pressure to automate transport processes efficiently and reliably is increasing in the process industry partly due to a lack of skilled workers and interruptions to delivery chains. Increasing numbers of companies are therefore choosing automated guided vehicles (AGV) and autonomous mobile robots (AMR). However, where the transport of production resources needs to meet the most stringent cleanliness requirements, any contamination of the production environment can lead to downtimes. Particles floating in the air that pollute a batch of medicines or damage highly sensitive semiconductor substrates (wafers) can cause significant issues. Therefore, every component of automated transport vehicles must be designed with a view to cleanliness. A sticking point here has been the supply of power to the transport robots.
Until now, AGVs and AMRs have been charged automatically with sliding contacts. With this charging method, a robot travels across copper contacts set into the floor. The transmission of power begins when direct contact is made with the charging contacts on the underside of the vehicle. The problem is every charging process creates copper abrasion, which pollutes the environment. In addition, there is a risk that employees could trip over the charging points, and this is a danger to process safety. Traditional contact charging plates sit several centimetres above the floor so that the power supply works despite a robot being clear of the floor. Finally, the systems require considerable maintenance, as broken or dirty contacts have to be replaced.
Inductive power supply
For this reason, AGV and AMR manufacturers are increasingly turning to inductive point charging systems where the transfer of power is contactless, following the principle of magnetic induction. As soon as a vehicle has reached the loading pad of an inductive point charging unit, the charging process starts automatically at full power within a second. Battery fast charging systems such as Wiferion’s etaLINK are encapsulated and can operate without mechanical components. In this way, Wiferion enables charging to take place with minimal particle generation. Additional reliability is provided by PohlCon’s Wireless Charging Protection System (WCPS), specially designed with a double bottom system for use in cleanroom environments. This means that the toughest cleanroom requirements can be met.
In addition, the charging technology allows production to be maintained without interruption for charging the battery. Instead of moving to permanent charging stations, the robots are provided automatically, at frequently used stations such as processing machines, with the quantity of energy they need for their transport tasks through “in-process charging” during their workflow – so no time is wasted. The vehicles can thus carry out their transport tasks in a continuous 24/7 operation without needing to interrupt their transport work for charging breaks. This increases the productivity of a fleet of robots by up to 32% in comparison with traditional charging technologies.
The etaLINK charging pads can be installed completely flush with the floor, at the side or like a tile. The charging station does not impede the flow of work, and there is no longer any risk of tripping. Another plus point is the flexibility of the application. If the production layout is changed, the charging points can be relocated in a few quick steps. In addition, no maintenance is required due to broken or dirty contacts.