0.15 0.15 0.08 0.15 .] ,015 T K =r 333.1 314.1 486.4 28 .] 21 T [0.1 0.1 0.1 0.1 0.1 0.1 .] ,01 T 161.5 248.2 362.6 449.3 362 .]2 T ka2 = [5 8 5 18 18 18 ],5 T and k2 = diag(10.0 6.0 5.0 3.0 2.6 1.9 1.1). The initial and desired feature point coordinates are sinitial = [466.5 116.1 300.3 148.9 and sd = [449.3 161.5 248.2 respectively. The initial and desired joint angles are qd 1.211 0.034 1.088 −0.215]T o = and qinitial −0.184 1.214 0.121 1.164 −0.0395],T tial joint velocities are []. q 0 00000 0 T Figure 6 shows the actual feature point trajectories in the camera view of RealSense D435i. The four corners of = [−0.216 −0.704 −0.028 = [−0.0799 −0.763 respectively. The ini(a) (b) Figure 6. A schematic diagram of the actual trajectory of feature points in the camera's FoV (green cross: current feature points; red cross: desired feature points). (a) A classic visual controller and a PID torque controller and (b) a constraint IBVS controller and a sliding mode torque controller. PID: proportional-integral-derivative. -50 -50 00 50 100 150 200 250 300 350 400 450 100 200 300 400 u (Pixels) (a) Feature 1 Feature 2 Feature 3 Feature 4 500 600 50 100 150 200 250 300 350 400 450 100 200 300 400 u (Pixels) (b) Final Point Starting Point Figure 7. The trajectory curve of visual features in the pixel plane. (a) A classic visual controller and a PID torque controller and (b) a constraint IBVS controller and a sliding mode torque controller. The dotted lines represent the boundary of the camera's FoV, where , u ma 500x = v ma 405x = (pixels) and umi 180n = , v mi 95n = (pixels). PID: proportional-integral-derivative. DECEMBER 2022 * IEEE ROBOTICS & AUTOMATION MAGAZINE * 111 500 600 v (Pixels) v (Pixels)