Figure 7

Tendons tension trend during precision grasp. Precision grasp using the CyberHand PCs matrix. Thumb, index and middle tendon tensions summation trend is represented while following ideal and noisy trajectories. The thick black line refers to the ideal piecewise linear trajectory in Figure 6a (bold solid line); thinner coloured curves refer to noisy trajectories (noise maximum amplitude is 50 pixels for the red curve, 70 pixels for the green curve and 100 pixels for the cyan one). The dotted curve refers instead to the "right-angle" trajectory, and has been rescaled in time to fit inside the graph. Arrows highlight the instants when contact with the object is achieved and then lost. Tensions are calibrated in Newton using sensors characteristics.