Cybernetics made simple

The new TorqueWire series of integral servo systems creates a different approach to complex automatic machinery architecture. Torquewire motors are complete, self sufficient servo axis building blocks which allow the design, integration and operation of large multi axis systems with minimum hardware and surprising ease.

The TorqueWire motor systems consist of an advanced, high performance rare earth brushless servo motor, a DSP based, high voltage interpolating servo drive and a single or multi turn absolute encoder, all assembled in a very compact IP 68 protected frame.

The motor systems are controlled via a multi drop CanOpen field bus, linking together groups of motors on a single bus system. The motors are supplied from a common DC bus and braking energy from any drive is intrinsically recycled on any other axis on the network.

The performance of TorqueWire originates in the advanced design of both motor and drives.

The motor parts take advantage of a novel, patent pending winding design, along with new magnetic materials and a special winding technique, all of which result in a servo motor with about 60% of the size of a conventional servo design. Such advantage is invested in both temperature rise derating and space for the drive, so that TorqeWire motors, including the drive, are smaller than comparable motors with similar rating.

The built-in, DSP based drive is a step forward in power drive miniaturisation. According to the established Phase drive technology, neither electrolytic capacitors nor any components subject to ageing of temperature decay are used. All magnetics are planar, integrated in the drive PCB. The drive is an ultra compact, single board unit in high density SMD technology with no massive components and is vibration tested to 200 Hz, 5g. The drive is conformally coated and sealed; connection is via IP 68 industrial circular connectors.

Drive temperature, long considered the limiting factor in integral drives, is controlled with an accurate strategy; all components are rated for 120 oC operation, while the drive is temperature limited at 100 oC. The DSP senses motor temperature, power device temperature, and drive ambient temperature. All these data are available on the bus for application monitoring and optimization. Drive loss and EMI are minimized intrinsically by the drive location, with zero wiring stray capacitance and minimized winding capacitance.

In general, all servo systems are intrinsically limited in performance by the S/N ratio of the encoder signal. In the TW motors, the interpolating drive is positioned in close proximity of the encoder, thus ensuring the best possible position signal quality and integrity; the servo performance is consequently optimal.

The CanOpen protocol implementation of the TW series is in full compliance with the standards DS 301 and device profile drives DSP 402v2.0. TW drives are controlled in space, speed or torque. The servo loops are updated at 4 kHz frequency.

In the interpolated mode, a position profile synchronized with other axes is followed with a maximum throughput of 500 samples/sec, corresponding to a maximum mechanical bandwidth of 250 Hz, far in excess of the best mechanical systems available, The TW interpolates points with a second order spline. A separate, programmable, hardwired I/O which overrides all software instructions is provided to cater for machine safety requiremets.

The 2 wire, optically isolated digital interface, and the suppression of all other interfaces, grants reliability, fault tolerance and ease of installation, expecially in multi axes systems. The motors can be programmed and monitored via the CAN Cockpit Windows interface (supplied with all TW motors).

All TW motors embody a non volatile memory to store permanent data, settings and fault conditions irrespective of power supply availability.