Figure 4.1.: An Inverted Pendulum (IP) leg, with soft upper and stiff lower flexure. Both flexures are machined from Maraging steel. The dimensions of the flexures are shown in units of mm. The upper flexure is used in tension to prevent buckling. The lower flexure provides restoring forces for the IP leg. The magnets (red) for eddy current damping of the leg’s higher modes are distributed around the leg inside the upper bell. This upper bell is used to suspend the spring box. The lower bell supports balancing counterweights (blue) for fine tuning of the Centre of Percussion (CoP) effect. The CoP effect is explained in section 4.2. The photograph on the right-hand side shows the two flexures side by side. The calliper tips indicates the length (25mm) of the short flexure. The short flexure is shown within a cross-beam, from which the upper bell is suspended.