I. Planning and Control for Dynamic Nonprehensile Robotic Manipulation

Nonprehensile manipulation primitives such as rolling, sliding, pushing, and throwing are commonly used by humans but are often avoided by robots, who seem to prefer grasping.  Dynamic nonprehensile manipulation raises challenges in high-speed sensing and control, as the manipulated object is not in static equilibrium throughout the process.  An advantage, however, is that dynamics can be exploited to help the robot control object motions that would otherwise be impossible.

                  

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II. Integrated Planning and Control of Various Mobile Robots Using Differential Flatness

        

III. Differential Flat Designs of Under-actuated Mobile Manipulators

If a manipulator arm is mounted on mobile vehicles, the dynamics becomes highly nonlinear.  A challenging question is how to perform point-to-point motions of such a system in the state space of the mobile manipulator.  Moreover, if some of the actuators are absent in the mechanical arm, the mobile manipulator becomes under-actuated and consequently even harder to plan and control.   We investigated a methodology for design of a mobile manipulator, mounted with under-actuated arms operating either in a horizontal plane or in a vertical plane such that the combined system is differentially flat. We showed that by appropriate inertia distribution of the links and addition of torsion springs at the joints, a wide range of under-actuated designs are possible where the under-actuated mobile manipulator system is differentially flat.

         

- The two-link mobile manipulator and experimental results, developed and conducted by the SUNY Buffalo.

IV. Differential Flatness-based Robust Controller

For various reasons, slip between the ground and the wheel often exists in most of the real applications of mobile robots.  To achieve the desired performance when slip occurs, a controller that is robust to slip disturbances is required.   In the development of robust trajectory-tracking controllers, the structure of the differential flatness controller, which provides an integrated framework for planning and control, is extended to account for slip disturbances by adding a corrective control term. The simulation and experimental results showed that the proposed robust controllers are very effective in the presence of slip.

V.  Various Control Problems

    • Control of a Passive Mobility Assistive  Robot

A control methodology for a two-wheeled differentially driven mobile robot was developed in order to make the robot, which can be used as a mobility assistive robot, have passive mobility characteristics for the user’s safety.  The control law creates damper-like resistive forces on the wheels.

                        

    • Control of an agricultural vehicle: Simulations and Experiments

This work was another team work project for autonomous control of an agricultural farming tractor.  We provided a Lyapunov-based control algorithm  and our coworkers at the University of Valladolid (Spain) conducted experimental validation of the idea.

    

VI.  Baby Robot (Robot Enhanced Mobility)

  : The Capacity for Young Infants to Learn Real World Navigation, and Its Effect on Perception, Action and Cognition Development

I have conducted the “baby robot” project in which we provide very young infants (as young as 5-6 months) or special needs babies with mobility generated by a mobile robot to help them improve cognitive development as well as physical development.

   

- Prototype of the baby robot with Magellan Pro mobile robot.

- Designed the wooden cart & modified Logitech wireless Joystick for baby use.

- Command & data flow through wireless (TCP/IP) and RF

- 2nd wireless joystick for experimenter interruption.

- All necessary host, joystick, and control programs were coded with C/C++ under Linux.

  

    • Media coverage