Mark D. Bedillion

Lead and lag compensators with complex poles and zeros design formulas for modeling and loop shaping

Complex lead and lag compensators are new additions to the repertoire of compensator structures for loop shaping. This article facilitates the use of these compensators by providing explicit formulas that relate the parameters of the compensators to features of their frequency responses. Two examples illustrate the utility of these compensators for system modeling and controller design. While the examples involve low-order plants, the principles of employing the complex lead and lag compensators remain the same for higher-order systems. We plan to use these compensators as weighting functions with automated robust design tools. A weighting function is a transfer function whose frequency response magnitude is used to bound closed-loop response or modeling uncertainty. The complex lead and lag compensators provide new degree of freedom for selecting weighting functions. In particular, the steep magnitude slope in the transition region of these compensators more closely approximates an ideal step function than weighting functions appearing in the literature (Packard et al.)

Distributed Manipulation with Rolling Contact

The Modular Distributed Manipulator System (MDMS) is an array of actuators that is capable of manipulating objects in the plane. This paper presents a controller designed to transport objects to the origin of a coordinate system under rolling contact. A stability proof using the multivariable circle criterion directly accounts for discontinuities due to changing actuator sets. Simulations verify the controller’s effectiveness and show stability even when the contact switches between viscous friction and full rolling contact.

Distributed manipulation with stick-slip contact

Actuator arrays are planar arrangements of two degree-of-freedom actuators that cooperatively translate and orient objects for efficient manipulation. This paper derives the equations of motion for an object with the friction interface switching between slip and no-slip contact at each actuator. A controller derived from kinematics is presented and its stability analyzed with the multivariable circle criterion. Stability results are verified through simulation.

Trajectory tracking for actuator arrays

Actuator arrays are planar arrangements of two degree-of-freedom actuators that cooperatively translate and orient objects for efficient manipulation. This paper describes a trajectory tracking control law for macroscopic actuator arrays and its convergence properties. The control law is designed based on the kinematics of an object on the array. Its convergence properties are found using a direct solution of the Kalman-Yakubovich-Popov equations. Simulations show the control laws effectiveness and that the bounds are very conservative for objects under stick-slip contact

Parking Control of Mixed Conventional/Braking Actuation Mobile Robots Using Fuzzy Logic Control

In this paper a new mobile robot system, the mixed conventional/braking actuation mobile robot (MAMR), is introduced. Various actuation systems exist for mobile robots such as differential drive with motor-driven wheels, legged mechanisms, and others. The common characteristics of all those actuation systems is the use of conventional motors to move each degree of freedom. Robots with such actuation systems are generally complex, heavy, and expensive. This paper uses brakes in combination with conventional actuators to tackle those drawbacks. In this study, some of the conventional actuators are replaced by brakes resulting a new mobile robot platform. Two states of brakes (i.e. ON/OFF) which are obtained by assuming Coulomb friction at the brake are considered. This paper discusses the dynamics and parking control of such a robot using a fuzzy logic controller. Several Matlab/Simulink simulations with different initial conditions are done to show the effectiveness of the proposed controller.Copyright

Control for Robots With Braking Actuators in a Uniform Force Field

This paper concerns the control strategy of a robot with controllable brakes placed in a uniform force field. Without loss of generality this force field is assumed to be gravity, and the robot to be an object resting on an inclined plane. The controller’s objective is then to use the brakes to lead the robot into a desired position and orientation.The system’s dynamics were derived from Newton’s second law with a Coulomb friction model. The controller was derived from geometric properties and the energy equation. The controller was then tested using Matlab and Simulink on the dynamics that were derived. The results of the simulation shows high accuracy even with some disturbances, and uncalibrated parameters.Copyright

A distributed manipulation concept using selective braking

This paper introduces a new distributed manipulation concept whereby objects operating under the action of a uniform force field are positioned perpendicular to the force field and oriented by selectively applying braking forces at various locations on the object. We assume that the braking locations do not slip, which gives the object dynamics the familiar form of the pendulum equation, but with the pendulum hinge location changing as a function of time. Such a system may find applications in parts handling or in the control of robots descending on inclines. This paper discusses the dynamics of such a robotic system and the sequential control of lateral object position and orientation. Simulation results show the effectiveness of the developed control laws.

Trajectory Tracking Control for Actuator Arrays

Actuator arrays are planar arrangements of actuators with two degrees of freedom that cooperatively translate and orient objects for efficient manipulation. This brief describes a trajectory tracking control law for macroscopic actuator arrays and its convergence properties. The control law is designed on the basis of the kinematics of an object on the array. Its convergence properties are found using a direct solution of the Kalman-Yakubovich-Popov equations. Simulations show that the control law is effective and that the bounds are useful for objects under no-slip contact. Experimental results from a 20-unit prototype array demonstrate the controller performance.

Distributed Sensing in Actuator Array Manipulation

Actuator arrays are planar distributed manipulation systems that use multiple two degree-of-freedom actuators to manipulate objects with three degrees of freedom (x, y, and θ). This paper describes methods of sensing the position and orientation of objects on an actuator array using only binary object sensors at each actuator. The object sensor information, when combined, forms a binary image of the object which may be processed to recover object pose. The methods’ effectiveness for rectangular objects is verified via simulation.Copyright

Event-Based Temperature Control for Machining Using MTConnect

MTconnect is a newly-developed standardized communications protocol that is designed to make it easier to collect, transmit and leverage data from shop floor machine tools. However, MTConnect is a read-only architecture, i.e., it is currently used for monitoring and not control of manufacturing processes. This paper develops an event-based real-time control architecture using MTConnect and demonstrates feasibility on tool-tip temperature control of a small-scale CNC prototype machine. Analytical modeling provides a link between tool feed rate and tool-tip temperature. This model, which is verified through experiments, is used to develop both periodic sampling and eventbased PID control laws. The periodic PID controller is implemented on device to serve as a performance benchmark. Its performance is compared, both in simulation and experimentally, to an MTConnect-enabled event-based controller operating over the web.Copyright