(a) Force estimation using AM-FM
(b) Force estimation using fast enveloping
(c) Linear correlation between sEMG envelop and force according to (a)
(d) Linear correlation between sEMG envelop and force according to (b)
Figure 12: sEMG-force correlation results: raw force signals are processed by low pass filter with 15 Hz cutoff frequency. sEMG signals are filtered and smoothed with enveloping using two methods designed in Section 2.