METHOD FOR MYOELECTRIC CONTROL OF AN ARTIFICIAL LIMB

摘要

For myoelectric proportional control of an electric-motor-powered artificial limb, either proportional speed regulation or proportional gripping force regulation is performed. In proportional speed regulation, the set rpm value is determined from various rpm setpoints. The rpm setpoint is compared with the actual measured rpm of the motor and fed to a proportional-integral (PI) regulator as a system deviation. In the PI regulator, the system deviation is converted into a pulse-width-modulation (PWM) signal and the drive motor is then controlled at an rpm proportional to the actual electrode voltage. The actual current value of the drive motor is measured and compared with a set current maximum which, when exceeded, causes the PI regulator to be switched off. In proportional gripping force regulation, the maximum gripping force is divided into stages, with the actual electrode voltage corresponding to a certain number of stages. Each stage is associated with a pulse-width- modulation (PWM) value and a current shutoff value. Counting takes place from 0 to the number of stages specified by the current electrode voltage. Each PWM value is output with the equivalent current shutoff value. At the same time, the drive motor current is measured and compared with the outputted current shutoff value. Whenthis shutoff value is reached, the counter is increased by 1 and the next PWM value is output. When the counter reaches the number of stages defined by the actual electrode voltage, the set gripping force is reached and the drive motor is shutoff. The current value of the drive motor is measured and compared with a set current maximum which when exceeded, causes the drive motor to shutoff.