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Elie A. Shammas
Postdoctoral Fellow, MechE
No longer a member of RI.

Research Interests

Advanced Mechanical Design

I have designed and constructed several spatial robotic joints that are suitable for constructing three-dimensional hyper-redundant robot. For all joints, we sought to maximize the strength and the range of motion of the joint while minimizing weight and volume. The culmination of this work was a design patent and a state-of-the-art spatial hyper-redundant robot with unprecedented range of motion.


A section of a 2 DOF three-dimensional robotic joint for which we accqured a design patent.

A section of the 3 DOF spatial joint that we used for constructing the MEDUSA hyper-redundant robot.



Mechanics of Locomotion

The theoretical aspect of my graduate work dealt with the motion planning problem of underactuated mechanical systems. We developed a unifying theory that governs the locomotion principals of satellites orienting in space to snakes slithering on the ground. The generality of our approach did not penalize the accessibility of our results as we strived to present our results in a clear and intuitive way.


A sketch of the divoting dynamic model of RRrobot. This system represents satellites in space than can orient themselves along three axes using only two interanl control inputs.

A sketch of a kinematic snake with three passive wheels sets. Using only two inputs, the inter link angles, we are able to translare and rotate the snake robot in the plane.



Motion Planning (Geometric Control of Mechanical Systems)

To develop intuitive gait generation techniques that are applicable to a large class of mechanical systems, we took advantage of the geometric structure of the systems' configuration spaces as well as the symmetry of the laws of physics governing the systems' motion. Both tools, when studied and analyzed in the right frame work simplify the motion planning problem for underactuated mechanical system, thus, allowing us to devise large families of control inputs that steer these systems along desired trajectories.


A plot of a height function which we utilize to propose gaits for the controlable inputs of an underactuated mechanical systems such that we can steer the uncontrolable degrees of freedom in a desired way.

A plot of a vector field over the base space of an underactuated mechanical systems which defines the momentum conserving directions of motion.