Adaptive Robust Motion Control of Direct-Drive DC Motors with Continuous Friction Compensation

Figure 3

Experimental results and curve fitting of nonlinear friction.

(a) The overall friction identification data

(b) The zoom figure at zero velocity region in (a)

(c) The obtained static friction described in (2) with 𝑠₁=700, 𝑠₂=15, and 𝑠₃=1.5; the normalized friction level 𝑙₁/𝐾_𝑖=0.02, 𝑙₂/𝐾_𝑖=0.01