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Automated guided vehicles

CANopen drive with integrated speed sensor

Wittenstein has launched the iTAS toolkit for automated guided vehicles (AGVs) featuring the Simco drive with webserver functionality. Optionally, a CANopen interface is provided.

The modular toolkit is specially designed for automated guided vehicles (Photo: Wittenstein)

The Simco servo amplifier features up to 50 A nominal current. The on-board webserver enables online, platform-independent communication with the servo amplifier. For example, to check the operating parameters or important driving and status information. The idea is to provide a complete servo drive system for AGV manufacturers. The product is also suitable for electrically powered commercial vehicles. The company offers three packages of this toolkit: “compact”, “advanced”, and “performance”. Customers can also chose from a set of feature options like an additional speed sensor by Sick or an integral wheel with frame attachment.

Like the other servo drives in the series with up to 740 W, the Simco servo amplifier combines current control with current sensing. The webserver, which is stored in the drive allows continues condition monitoring, which increases the availability of the AGV system. Open and closed-loop speed control can be realized with the AGV’s host controller (e.g. PLC). The integrated STO (safe torque-off) function complies with SIL-3 (IEC 61508). Other drive safety functions like SLS (safe limited speed) or SOS (safe operating stop) can be implemented by means of a safety controller and safety encoders.

The integrated 3D acceleration sensor records all vehicle movements in x-, y-, and z-directions. It detects limit violations by measuring the magnitude of an absolute acceleration and saves these events in the servo’s EEPROM together with a time-stamp. If an AGV collides due to the fault of another vehicle, the collision can be reconstructed. The forces acting on the vehicle in a bend as a function of its speed or the gradient of a ramp, which the AGV drives-over can likewise be recorded and evaluated by means of the acceleration sensor.

Space-saving design

Installation in confined areas tends to be the norm with AGVs, which is why the servo amplifier was designed as a space-saving solution with a flat housing, despite being more powerful. It can be installed in any position using the built-in cold plate. An additional heat sink can be integrated as an option to guarantee optimal heat dissipation at all times. The AGV can be supplied with power from an accumulator, a capacitor or a combination of both. With its extended input voltage range from 12 VDC to 60 VDC, the drive system – is suited for almost any AGV power supply concept that revolves around accumulators or capacitors.

To warrant safe activation of the brake function even if the battery voltage is too low or too high, the drive has an integral buck-boost converter. The converter steps the on-board input voltage for the brake up (boost) or down (buck) accordingly – saving space and money that would otherwise be unavoidable for a separate power supply unit. To protect the electrical components and relay contacts, the servo amplifier has a built-in soft-start function, which limits high input currents to non-critical values, for instance when a vehicle battery is connected.


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