Designing systems for extreme environments

Providing power
One of the challenges in any embedded system deployed to an extreme environment is providing power. Whether it’s because of deployment in a remote location or because it must be self-contained, most embedded equipment for extreme environments uses battery power. Introducing batteries into a system also introduces additional weight and requires additional space, both of which are usually at a premium in embedded systems. The space and weight costs associated with the introduction of an adequate power source often affect the design (or redesign) of the entire system.

In the case of an autonomous robot, engineers need to power a controller, communication equipment and circuitry, motors, and drives, as well as provide sensor excitation, just to cover the basics. The power allocated for each of these subsystems determines the number of sensors allowable, motor and actuator power level, and the rate and range of communication. Trying to balance total power consumption between all the systems and still maintain all the desired functionality while meeting size and weight restrictions can drive most of the design decisions, and almost always involves trade-offs, with designers prioritizing certain characteristics of their systems over others.

Engineers are now trying to address the power challenge in embedded remote systems from both sides of the problem. One approach is to use some source of renewable energy to recharge the batteries and generate sustained power. The other is to alter the structure and operation of subsystems themselves to be smarter with the power that is available. Often both approaches are applied to the same design, as in the case of a solar-powered, programmable wireless sensor node installation.

Figure 1. This programmable wireless sensor node for voltage measurements is encased in an IP (ingress protection) enclosure for protection from the environment. Engineers can program it to perform selective sampling and sample averaging. Click on image to enlarge.

Renewable energy for embedded systems
Renewable energy still has its challenges, including variability in power output depending on environmental conditions and, again, size and weight restrictions. Equipping installations with renewable energy generation equipment also requires specialized engineering expertise to integrate the power source with the embedded system hardware. As renewable energy generation and storage technology continues to mature, however, so will the possibility to use it in a wider variety of remote applications.