Abstarct: Compliant actuation systems have been developed in recent years for a variety of possible advantages, such as establishing a safe human–robot interaction, increasing energy efficiency and reducing the effects of impacts. Flexibility is generally an undesirable feature in robot manipulators because it causes significant control problems such as vibrations and static deflection. In order to reduce the performance degradation, systems involving more than one active element for each actuated degree of freedom are being investigated to allow separate position and impedance regulations. This thesis presents a variable stiffness joint (VSJ) designed for a robot manipulator, as well as a control scheme to control the stiffness and position of the VSJ. Compliance is generated by leaf springs and two actuators are used to control the position and stiffness of the joint using four-bar lixnkages. Two actuators in parallel configuration are connected to the spring. Changing the effective length of the spring results in a change in stiffness. Two basic techniques in this Thesis has been proposed for measuring joint stiffness. The first technique relies on static stiffness and requires deformation measurements at the joint location given a known static force. The second strategy identifies joint properties baxsed on measured vibration data of a joined assembly. Static data is contained within dynamic data. After estimating the exact amount of joint stiffness, a linear quadratic regulator (LQR) controller only and with integral state feedback control is developed for angular position control of a flexible joint manipulator. Then this is extended to incorporate input shaper control schemes for complete elimination vibrations of the flexible joint system.