Powered Knee System

Sterling Medical Devices participated in the development of a powered knee system. The powered knee system serves as a prosthetic limb that is highly adaptable to various movements, thanks to data recorded by sensors.

The system’s software employs a mixed-signal microcontroller (specifically, an MSP430) to gather data from sensors and adjust the response of the motorized knee system. The software update and parameter changes are inputted via a Bluetooth channel. All software was written in C++ and compiled using VS2005.

In the first phase, Sterling offered its consulting services to review and update how the product and software can be further developed in order to meet the requirements document for the Power Knee system and PC Control system. In the second phase, Sterling performed an independent execution of the software verification and validation protocols.

The powered knee system had two issues. The competitor’s driver package reassigns the driver from Bluetooth radio to the Widcomm drivers, thus disabling our client’s product. In addition, the client’s products employ a Bluetooth class I radio; the operating system of computers with internal Bluetooth radios generally pick the internal radio limiting range. The system uses RFCOMM to communicate with remote product using the Windows socket interface (Winsock).

In the third phase, Sterling proposed various solutions to interface the system to the Widcomm driver system and force reassignment for the radio to the Microsoft drivers. In the fourth phase, Sterling upgraded the system’s limited CPU, ported the system to new software with a higher clock frequency, and updated the tool chain to a newer version.

All work was done on Sterling’s ISO 13485 compliant QMS then transferred to the client’s QMS.