Fig. 6From: Energy-efficient control of a screw-drive pipe robot with consideration of actuator’s characteristicsValues of \(F(\alpha )\). a \({f_n}=0.5\) and \({f_t}=0.01\) versus \({f_n}=0.5\) only. b Zoom in figure of (a) with the interval from \({8^\circ}\) to \({20^\circ}\). c \({f_n}=0.5\) and \({f_t}=0.01\) versus \({f_n}=0.5\) and an artificial coefficient 0.91 times (13)Back to article page