NOW Technologies is a close-knit, dedicated team of professionals working to help people with disabilities to live an independent life. Based in Budapest, Hungary, and founded in 2014, NOW Technologies works closely with injured and disabled users and with medical and rehabilitation professionals. Their requirements and feedback are pivotal to ensure that their products are not only safe but are also sufficiently intuitive to require the least amount of training possible.
Proportional Headset Controls
A joystick is the most commonly used input device to operate a power wheelchair, but not everyone has the physical ability to operate a wheelchair using one. For these people, alternative input devices are required, such as a headset. Proportional controls allow the user to move in any direction, as the movement of the chair is literally proportional to the movement of the input device. Nonproportional controls require less coordination and motor control, as each direction and speed is preprogrammed.
The company's Gyroset Glory is a discrete, comfortable headset that enables users to control their computer and, when used in combination with Gyroset Link, empowers them to drive their power wheelchairs with the same device. As development continues, functionality will expand to provide a single controller for a host of applications. The company settled on STM32 M3 and M4 devices for the Gyroset range and included the Atollic compiler as part of its Linux-hosted tool chain, along with LDRArules to perform static analysis.
Selecting a Toolchain
Although the early headsets were not required to comply with functional safety standards, upcoming versions of the controllers will give wheelchairs an autonomous capability and so will clearly be safety critical. For that reason, software was developed in accordance with IEC 62304:2006 “Medical device software – Software life cycle processes,” while the product as a whole meets the EN 60601 and ISO 7176 standards.
IEC 62304 requires that “to consistently achieve the desirable code characteristics, coding standards should be used…” and to achieve that, NOW opted to comply with the MISRA C:2012 standard. The insistence on compliance with coding standards such as MISRA are a common theme in functional safety standards across the sectors, and it is easy to see why. They bring a wide range of benefits to the resulting code base, by
Promoting portability and avoiding unexpected results.
Ensuring that there is no reliance placed on compiler- or platform-specific constructs.
Identifying unreachable or infeasible code, which often indicates a defect that will, at the very least, impact software maintainability.
Prohibiting certain language constructs known to be a source of common errors or security vulnerabilities.
Measurably reducing program complexity.
Improving program testability, easing standard compliance and certifiability.
Safety and Security
Mark Istvan, managing director of NOW Technologies, notes, “The connected nature of the Gyroset controller family meant that neither security nor safety, were ever far from our thoughts.”
MISRA C:2012 is designed to be used with any critical system, whether it is safety critical, security critical, or both. “Although we clearly wanted the best technical solution for our products, cost is always a factor in the commercial world,” he says. “Not only is it a consideration for the initial purchase price, but ease of use was also important for us. We simply couldn't afford to spend time struggling with a complex interface. Happily, LDRArules was easy to install and to learn.”
LDRArules has been a vital component in adhering to the IEC 62304 standard, and TÜV certification has made its qualification for the project far less onerous than would otherwise have been the case. “LDRArules’ SGS-TÜV SAAR certification was certainly an influential factor in our decision to go with LDRA,” says Istvan.
A Vision of the Future
The company has set additional goals for the technology. “Our goal is to help people with disabilities to live an independent life, by providing them with affordable solutions to communicate, create, and work independently, and to enable them to live their lives with mobility,” says Istvan. “There is nothing more frustrating for any individual than for disability to limit their potential. Our products seek to reduce such limitations to an absolute minimum.”
Longer term, he also sees a future outside this domain. “There is big incentive in this particular market to get things right first time,” he says. “Because of the real risk to personal health, it is simply not feasible to place a prototype for beta test. As a consequence, any feedback we get arrives very late in the development life cycle.”
“Getting things right first time is a very portable capability,” he notes. “When combined with the more obvious attribute of a familiarity with the demands of functional safety standards, I believe it puts NOW Technologies in a great place to expand into medical robotics, industrial applications, and beyond.”
Wherever the future takes NOW Technologies, it seems certain that LDRA will be involved. “We will definitely continue to use LDRArules in our future projects and will consider other LDRA products as our activities diversify,” says Istvan. “LDRArules has been invaluable to us in providing evidence of our adherence to the IEC 62304 standard. I would estimate that we have saved at least €200k by using the tool, which represents a very speedy return on investment for us.”