Joey K. Parker

Inverse kinematics of redundant robots using genetic algorithms

Genetic algorithms, which are robust general-purpose optimization techniques, have been used to solve the inverse kinematics problem for redundant robots. A genetic algorithm (GA) was used to position a robot at a target location while minimizing the largest joint displacement from the initial position. As currently implemented, GAs are suitable for offline programming of a redundant robot in point-to-point positioning tasks. The GA solution needs only the forward kinematic equations (which are easily developed) and does not require any artificial constraints on the joint angles. The joint rotation limits which are present in any feasible robot design are handled directly; so any solution determined by the GA is physically realizable. Finally, the GA works with joint angles represented as digital values (not continuous real numbers), which is more representative for computer-controlled robot systems.<<ETX>>

Curriculum integration in the freshman year at the University of Alabama-foundation coalition program

The University of Alabama presented its first set of freshman year courses as part of the NSF sponsored Foundation Coalition during the 1994-1995 academic year. The three major thrust areas of this coalition are: curriculum integration; technology enabled education; and human interface issues. The focus of the paper is on the integration aspects of the freshman year engineering, mathematics, and sciences curriculum. Most freshman level mathematics, chemistry, and physics courses are taught in isolation from each other. Consequently, there is relatively little interaction on the education level between engineering professors and their colleagues in the math and science departments. As a result, most engineering programs lose many students during the freshman year. Our solution to this problem is an integrated set of courses for all engineering majors in chemistry, engineering, mathematics and physics, which must be taken together. The authors were the instructors for the initial offering of the courses mentioned above. The paper focuses on several specific examples of curriculum integration that have been attempted, along with observations about the success of the program. The Foundation Coalition consists of the following: Arizona State University, Maricopa Community College District, Rose Hulman Institute of Technology, Texas A&M University, Texas A&M University Kingsville, Texas Womens University, The University of Alabama.

Teaming in technical courses

As a result of the University of Alabama participating in the Foundation Coalition, the 1994-1995 academic year saw a completely new curriculum being prototyped for a class of 36 volunteer students within the college. The curriculum in question provides an integrated 13-hour sequence of calculus, physics, chemistry and engineering design for the students. One of the central themes to this sequence is the concept of teams and teaming. Students work in teams of four students throughout this course sequence. These teams operate as a unit for all classes, mathematics recitations, physics and chemistry laboratories, and all engineering design projects. A number of strategies for how to proceed were identified. Concern was placed on ensuring that students gain both the ability to function effectively within a team environment and also demonstrate their own individual ability to perform the task in question. This paper examines the processes by which teaming is performed within the integrated freshman year of the Foundation Coalition. It looks at successes that have been realized and also point out techniques that should not be repeated. The authors summarize their opinions about the strengths and weaknesses of the process, as well as identifying the principal lessons learned for both future semesters of this curriculum and other individuals interested in incorporating teaming into their own courses. In addition, the authors comment on the similarities and differences between freshmen students and upper-level engineering students with respect to teams and teaming.

The Foundation Coalition freshman year: lessons learned

Three years ago, mathematics, science, and engineering faculty at the University of Alabama (UA) designed a new set of freshmen courses which integrate science and engineering topics, promote active learning, and incorporate computer tools. The new courses have now gone through two cycles (1994-95 and 1995-96 academic years). The original goals of the new courses are presented followed by discussions of some of the advantages and disadvantages of the approaches.

Capstone senior design at the University of Alabama

The mechanical engineering program at the University of Alabama has had a two-course capstone design sequence (the Design Clinic) since the late 1970s. Although several changes have been incorporated over the years, the use of external industry-sponsored projects has remained a constant. Students participate in a common, competitive design project during the first two-thirds of the first course (ME 489). During the last third of the first course and the entire second course (ME 490), each team of three or four students works on a single, extended external project. We focus on the extended design activity. The overall organization of the course sequence and projects, including faculty support options and the process used to select student project teams, is outlined. We describe our various sources of projects, along with some of the possible advantages and disadvantages of each. Financial considerations for the course sequence and the impact of finances on project selection are also covered. Finally, brief descriptions of several recent projects are given. Interested faculty members should be able to use these suggestions in the development of their own senior design courses.

Engineering design in the freshman year at the University of Alabama-Foundation Coalition program

A pair of courses, Foundations of Engineering I and II, form the two-semester engineering component of Foundation Coalitions integrated freshman year at the University of Alabama (UA). These courses replace two existing freshman engineering courses which are devoted to computer programming and engineering graphics. In order to present a more realistic and interesting introduction to engineering as a profession, the courses focuses on the engineering design process. Both courses are organized around four three-week-long design projects. The projects are selected from a variety of areas, covering the breadth of engineering disciplines taught at UA. The design projects also complement the current subject matter of the integrated mathematics, chemistry and physics courses. For example, while both physics and chemistry are introducing the ideal gas law, the engineering project involves the design of a compressed natural gas tank for an automotive application. Each design project requires a team report in written and oral form. The students are introduced to a variety of computer tools to aid their presentation of reports, such as word processors, spreadsheets and presentation packages. Student access to the Internet and e-mail is also provided. This paper provides an in-depth examination of the first of these two courses. It includes a brief overview of the relationships that exist between the integrated courses in the freshman year a detailed examination of the nature and scope of the design projects included within the course, and feedback from both faculty and students on the merits of the approach.

Artificial neural network for identification and tracking control of a flexible joint single-link robot

An artificial neural network for identification and tracking control of a nonlinear flexible joint robot with model reference adaptive control structure is developed. Neural network identification (NNI) is used to obtain a dynamic model of a flexible joint robot to be controlled. Once NNI has closely matched the dynamic model of a flexible joint robot, neural network control (NNC) of tracking trajectory of a flexible joint robot is designed. Both tasks are completed using the backpropagation neural network. The method is shown to be a more simple, robust and adaptive learning control system than traditional control design for tracking control of a flexible joint single-link robot.

Further consideration of an electromechanical thrust vector control actuator experiencing large magnitude collinear transient forces

Thrust vector control (TVC) for the Space Shuttle Main Engines (SSMEs) is accomplished by hydraulic servo actuators. Marshall Space Flight Center (MSFC) is developing electromechanical actuator technology to be physically and functionally interchangeable with the existing hydraulic actuator. One of the major concerns for this design task is the large transient loads experienced by the TVC during start-up and shut-down. A non-linear model is developed to overcome the problem of integrator wind-up. A need is shown for some mechanism such that the system characteristics are different during transient force disturbances and during nominal servo conditions. It has been proposed that increased system damping during the transient force loading offers the best disturbance rejection.

Design of a robotic feeder

The use of US Office of Technology Assessment (OTA) recommendations to develop the design specifications of an inexpensive two-degree-of-freedom robot arm for use in rehabilitation applications is described. The current status of the robotic self-feeder is presented along with the mechanical, electrical, and control software design.

Inductive load current harmonic injection

Induction motor audible noise can be related to the frequency content present in the stator winding currents. These currents produce time varying air gap fluxes which in turn produce exciting forces resulting in vibrations in the mechanical structure. By adding harmonics into the winding currents, additional frequencies can be added to the air gap flux and audible noise. If the additional frequencies can be made to mask the switching related noise components, a motor drive combination will be less annoying than an unmasked combination. This paper shows results obtained by using a wait-hop strategy to extend the range of frequencies obtainable by using a look-up table, and a multiple index implementation for signal construction.