This work thesis is dealing with planar mechanisms. It?s concentrated on definition the topic, enumeration methods of mathematical description of mechanisms and occasion of simulation with usage information technology. It?s going mainly on GeoGebra program, in which were created most of schemes and models mechanisms. Created models are recorded on attached CD. Important charter of this theses are mechanisms used to draving planar curves, ending with mechanisms used to drawing straight line.

In this research a variable-stiffness compliant mechanism was developed to generate variable force-displacement profiles at the mechanisms coupler point. The mechanism is based on a compliant Roberts straight-line mechanism, and the stiffness is varied by changing the effective length of the compliant links with an actuated slider. The variable-stiffness mechanism was used in a one-degree-of-freedom haptic interface to demonstrate the effectiveness of varying the stiffness of a compliant mechanism. Unlike traditional haptic interfaces, in which the force is controlled using motors and rigid links, the haptic interface developed in this work displays haptic stiffness via the variable-stiffness compliant mechanism. The force-deflection behavior of the mechanismwas analyzed using the Pseudo-Rigid Body Model (PRBM), and two key parameters, KQ and g,were optimized using finite element analysis (FEA) to match the model with the behavior of the device. One of the key features of the mechanism is that the inherent return-to-zero behavior of the compliant mechanism was used to provide the stiffness feedback felt by the user. A prototype haptic interface was developed capable of simulating the force-displacement profile of Lachmans Test performed on an injured ACL knee. The compliant haptic interface was capable of displaying stiffnesses between 4200 N/m and 7200 N/m.

Series elastic actuators (SEAs) have numerous benefits for force controlled robotic applications. This thesis presents the design and assembly of a set of compact, lightweight, low-friction linear SEAs for the legs of the Tactical Hazardous Operations Robot (THOR). The THOR SEA pairs a ball screw driven linear actuator with a configurable titanium leaf spring. A removable pivot changes the effective cantilever length, setting the compliance to either 372 or 655 kN/m. Unlike typical SEAs which measure actuator load through spring deflection, an in-line axial load cell directly measures actuator forces up to the commandable peak of 2225 N. The continuous operating range of the actuator is computed, along with an evaluation of the range of motion and torque profiles for the parallel hip and ankle joints. With a focus on a large power-to-weight ratio and small packaging size, the THOR SEAs are well-suited for accurate torque control of the parallel joints on the robot. Linearly actuated joints, especially ones driven through a crank arm, tend to suffer from a loss of mechanical advantage toward the ends of its limited range of motion. To augment the range of motion and mechanical advantage profile on THOR, an inverted Hoeken's linkage straight line mechanism is paired with a linear SEA at the hip and knee pitch joints on the robot. The resulting linkage assembly is capable of delivering nearly constant peak torque of 115 Nm across its 150 degree range of motion. The mechanical advantage profile of the Hoeken's linkage actuator is computed for the nominal case, as well the deviation resulting from maximum deflection of the titanium beam. / Master of Science