Biomedical Engineering Reference
In-Depth Information
FIGURE 5-37
EMG signal after
amplification and
filtering.
FIGURE 5-38
Outputs from the
rectifier and
envelope detector.
the signal shown. Therefore, a precision full-wave rectifier shown in the previous section
should be used. This is followed by a low-pass filter to produce only the signal envelope,
as shown in Figure 5-38.
Various techniques are available for using this envelope to actuate pneumatic artificial
muscles, and these are addressed in detail in Chapter 10 The simplest method is to open
the pneumatic solenoid valve to the actuator if the envelope exceeds a threshold voltage
and to keep it closed if the level is below this. A comparator, discussed in the following
section, followed by a power transistor can be used to control the solenoid, as shown in
Figure 5-39.
FIGURE 5-39
Threshold
voltage-based
control of a
pneumatic solenoid
valve.
