New-Tech Europe | November 2016 | Digital edition

• Signal distribution: Signal distribution requirements center around maintaining the integrity of the signal waveform. For high-data-rate systems, this may involve controlled-impedance connector designs and careful attention to signal-to-noise ratios. The magnitude of the required connector resistance is strongly dependent upon the devices in the circuitry the connector must interconnect. For many devices, high connector resistance - hundreds of milliohms - can be tolerated. • Environmental considerations: Harsh environments, such as deep ocean or vibration sensitive surroundings, may constrain the traditional connector application and design. There may also be harsh and safety-critical applications, such as gaseous environments, which limit the application of contact technology. • Corrosion: Corrosion occurs in many forms and can be classified by the cause of the chemical deterioration of a metal. The most common form of corrosion is rust or ferric oxide. Galvanic corrosion, or dissimilar metal corrosion, occurs when two different metals are located together in a corrosive electrolyte. • Movement: Cabled solutions are generally constrained in their movements. Wear and tear on cables coupled to motor-driven, rotating subsystems, such as robotic arms, can lead to downtime, severely affecting productivity. A classic example is a robotic arm, which may have to move along multiple axii. Traditionally, rotation with reliable connectivity is achieved using slip rings that are connected to stationary rings via brushes. Cables are used to position these copper rings in close proximity to enable physical contact with carbon brushes. • Mating cycles: The connector may be designed to meet specified mating frequency and cycles from a few hundred to thousands. Cycle-life requirements affect the design and

Data Link

Pro

Challenges

Capacitive coupling

Low EMI. Also suitable for ring structures

Requires significant plate area, challeng- ing for tiny rotating couplers, sensitive to changes of material/ fluids Should generate a cir- cular polarized wave to support rotation No high bandwidth without OFDM, but that increases latency

RF, 60 GHz (OOK, ASK, QAM)

Large bandwidth (>1Gbps), low latency (nanoseconds) Easy near field antenna design (simple loop), RF solutions widely available

RF, 2.4/5 GHz (e.g. GFSK, MSK, ASK)

RF, sub GHz (e.g. FSK) Easy near field antenna design (simple loop), RF solutions widely available

Low bandwidth (sub Mbps)

Via ICPT power link

No separate antenna needed Very high bandwidth possible (>10Gbps)

Low bandwidth (10- 100kbps) Sensitive to dust and dirt, precision optics & lenses needed

Optical

Figure 1. There are numerous options for a contactless data link, including 2.45-GHz RF, but power links are for now best achieved using inductively coupled power transfer

Figure 2. In inductive coupling, the coupling is determined by the distance (z) and the ratio of D2/D, while the efficiency of power transfer between transmitting coil L1 and receiver coil L2 depends on the coupling (k) between the inductors and their Q factor

critical for power connectivity. Arcing is also significant in power applications,

especially where there are hazardous gas environments.

New-Tech Magazine Europe l 31