fig5

Figure 5. The work performed by multiple muscles. (A) Weight lifting with both BIC and TRI muscles. The BIC phase refers to the period when BIC dominates in positive work performance, and the TRI phase denotes the period when TRI contributes to the major part of positive work; (B and C) Measurements of C_s and EMG on the BIC and TRI muscles throughout the lifting process; (D and E) Comparison of ΔC_s and the muscle contraction displacement for BIC and TRI. The regression of ΔC_s and muscle contraction displacement was characterized by R² = 0.98 and 0.85 for BIC and TRI, respectively, validating the capacitive sensing for muscle deformations during collaborative muscle motions; (F and G) Comparison of the RMS of EMG and the muscle contraction forces for BIC and TRI. The regression of RMS of EMG and muscle contraction force was characterized by R² = 0.98 and 0.91 for BIC and TRI, respectively, validating the feasibility of muscle force sensing with EMG during collaborative muscle motions; (H and I) Curves plotted with ΔC_s and the RMS of EMG measured on the BIC and TRI; (J and K) Comparison of E_m and E_w (= E_w-BIC + E_w-TRI) with their linear regression of R² = 0.92, where E_w-BIC and E_w-TRI are the muscle work performed by the BIC and TRI muscles, respectively; (L) Comparison of E_w and E_m for multiple lifting cycles. The E_w summed for both muscles linearly related to E_m with R² = 0.89. BIC: Biceps brachii; TRI: triceps brachii; EMG: electromyography; RMS: root mean square.