A microprocessor-based biofeedback cane system

A system has been developed to measure vertical forces between a cane and ground while walking. An audio alarm sounds when applied forces are not within pre-determined limits. The system employs two types of sensors attached to the cane, a force sensing resistor (FSR, Interlink, Santa Barbara, CA.) and a strain gage bridge (Mlcromeasurements Group, Rallegh, NC). The sensors provide input to the portable data acquisition circuit which is designed to perform analog to digital conversion and store the force data using a calibrated look-up table. The alarm is controlled on the basis of look-up table values. Thresholds for the alarm are set as a ratio of subject weight which is input to the system prior to use. High-speed CMOS technology and the Motorola 68HC11 microcontroller were used in the design to limit power consumption.