The usage scenarios for automated guided vehicles in the health sector are very complex. Light, sensitive and fragile goods must be transported as well as tons worth of medical devices. AGV manufacturers therefore require differentiated drive systems for the different solutions. Fan and drive specialist ebm-papst offers the right solution here with a variety of drive combinations. With the “ArgoDrive”, a compact and easy to integrate driving/steering system including wheel was developed, which can move loads of up to 100 kg, 300 kg or 500 kg per drive axis in the Light, Standard and Heavy versions (Fig. 3). In the maximum expansion stage with four driving/steering systems in the Heavy version, it is easy to achieve a load capacity of two metric tons, i.e. even x-ray systems that weigh tons, like a CT scanner, are easy to move.
Compact despite high performance
The installation dimensions and the electrical, mechanical and control interfaces are identical in all three variants, only the impeller diameter (80 mm, 100 mm, 145 mm) and thus the ground clearance differ. Thanks to the ArgoDrive’s compact horizontal dimensions of 250 mm x 170 mm, the AGV manufacturer has enough space to accommodate other components, e.g. for control systems, safety modules or batteries. This keeps the overall vehicle height low, which meets the requirements of goods transfer stations or the design of mobile robotics. The ArgoDrive is a safety extra-low voltage drive system (48 VDC), so the requirement for documentation is manageable and commissioning is simplified. In addition, the battery voltage can be used directly without a voltage booster and/or inverter. The intelligence integrated into the drives also enables condition monitoring and predictive maintenance depending on the version.
Each drive unit consists of two motors, transmission, sensors and all the necessary connection plugs. With the superposition gear, the two motors contribute towards steering, acceleration, movement and braking, depending on requirements. The infinite steering angle enables free-range vehicle movement – even from a stationary position. The use of two driving/steering systems, mounted diagonally on the left and right side of an AGV, guarantees omnidirectional freedom of movement and narrow maneuvering, e.g. when avoiding things.
Two additional freely moving support wheels on the front and rear provide the AGV with the necessary load handling and stability. Depending on the size of the automated guided system and the weight to be moved, three or four driving/steering systems can also be installed. Transport solutions equipped with the ArgoDrive can move large loads with full functionality, even on inclines of up to 10 percent. In other applications, it may make sense to use a single drive unit, for example as a maneuvering aid for hospital beds.
Omnidirectionality for AGVs with ArgoDrive
The ArgoDrive from ebm-papst is a new solution for AGVs, combining propulsion and steering functions in a single assembly. This unit consists of motor, transmission, omnidirectional steering, sensors and all the necessary connections. Thanks to a superposition gear, its two motors contribute to steering, acceleration, movement and braking, depending on requirements.
The infinite steering angle enables space-saving, free-range vehicle movement – even from a stationary position. One ArgoDrive per axle already guarantees full omnidirectionality. Depending on the required size of AGV and the weight of the goods to be moved, three or four driving/steering systems can also be installed. ebm-papst offers its ArgoDrive in Light, Standard, and Heavy versions for payloads of up to 100, 300 or 500 kg per wheel, respectively, in order to meet every requirement for moving masses, braking, and mastering inclines in a scalable way. With four Heavy versions, a total vehicle weight of up to two tons is then possible. Consistent gearbox dimensions across all sizes with standardized mounting points and uniform, high-quality plug connections allow the AGV to be adapted to project-specific requirements within minutes.
Low-maintenance and fail-safe
Reliable operation is an important aspect for AGVs in all areas of medical technology. Unscheduled downtimes reduce availability, as does maintenance being required at regular intervals. The drive units are therefore designed for reliability for the entire service life. If the wheel surface wears down after a long period of operation, a simple “tire change” is possible without removing the drive unit. Nothing gets stuck on the closed wheels. The smooth surfaces of the wheel can be easily cleaned or disinfected. Contact errors on the electrical interfaces of the drive systems are also no danger because the necessary cables and plugs of the driving/steering system are permanently installed in the vehicle and tried-and-tested industrial connectors ensure a safe connection to the control system. In the event of a defect, the entire unit can also be replaced quickly in just a few steps.
Safe on the move
To protect people, the safety of AGVs is even more important than reliable operation. The AGV must be able to initiate emergency braking immediately if protective zones are breached in front of the vehicle. Appropriate safety sensors ensure that the environment is continually scanned. If the protective zone is breached, the drive system must give the safety control system the command for a safe stop. Then a high braking power is the main thing required for the drives. Here, the ArgoDrive can enable a delay of up to 2.5 m/s2 using the electric motor brakes, and immediate emergency braking is also possible using the additional integrated brake. In order to prevent uncontrolled movements, the drive unit also comes to a safe stop if the AGV power supply fails. This means that the ArgoDrive supports all typical and necessary safety requirements.
For this purpose, the individual driving/steering system is actuated by two external controllers. The signals for the steering angle are also redundant and the position can be queried at any time. The STO function (Safe Torque Off) integrated in the controllers ensures a safe stop in the event of an emergency. This makes it easy for the AGV manufacturer to achieve further collision protection measures. ebm-papst is happy to help if you have questions relating to the safety of the entire vehicle. Since a drive system for AGVs also has to communicate with higher-level systems, connection via CANopen, EtherCAT or Profinet is possible depending on the external controller.
Therefore, the ArgoDrive provides a flexible drive solution for AGVs that does not require compromises on free-range mobility and compactness, whether that is in hospitals, pharmaceutical production, rehabilitation equipment or health care applications in domestic environments.