HarrisFest - IEEE Control Systems Society

CONFERENCE REPORTS

«

HarrisFest

O

n May 22, 2010, a symposium in honor of Harris McClamroch was held at the University of Michigan to celebrate Harris’s lifelong achievements in nonlinear dynamics and control on the occasion of his retirement. Since receiving his doctoral degree at the University of Texas, Austin, in 1967, Harris has been a faculty member in the Department of Aerospace Engineering at the University of Michigan. He is a former editor-inchief of IEEE Transactions on Automatic Control and a former president of the IEEE Control Systems Society. Additional professional activities include program chair, 1994 IEEE Conference on Decision and Control, and general chair, 1999 IEEE Conference on Control Applications. In recognition of his outstanding contributions, he received the IEEE Third Millennium Medal in 2000. He is also a member of AIAA, SIAM, and AAAS. He advised 27 doctoral students over his 43-year career. The symposium, titled “Synergies and Interplay of Nonlinear Dynamics and Control,” began with welcoming remarks by Taeyoung Lee, a former doctoral student and currently a faculty member at Florida Institute of Technology. Ilya Kolmanovsky then presented Harris with an engraved plaque commemorating the symposium. Ilya is also a former doctoral student, and he recently rejoined the University of Michigan as a faculty member after working at Ford for 15 years. This presentation was followed by opening remarks from Harris, summarizing his experiences and perspectives on his research career. Digital Object Identifier 10.1109/MCS.2010.937816

The first presentation of the technical program was given by Amit Sanyal, a former doctoral student and currently at the University of Hawaii. His talk, “Riccati Equations, Flexible Spacecraft, and Variational Integrators: The Trajectory of N. Harris McClamroch in Nonlinear Dynamics and Control,” provided an overview of Harris’s research and contributions to this field over his academic career. Harris’s early contributions included sensitivity of linear optimal control and optimal estimation problems, stability analysis of interconnected systems with static nonlinearities, and stochastic

modeling and control in manufacturing. During the late 1980s, Harris’s research turned toward control of nonlinear mechanical systems; this direction characterized the rest of his research career. In particular, by the early 1990s, Harris had found a rich harvest of nonlinear control problems to be solved for nonholonomic mechanical systems, which cannot be controlled by feedback linearization. Harris’s research on control of nonholonomic systems occurred at the peak of his career and was influential in defining important control problems and issues, besides influencing the research directions of numerous researchers in this area. This talk also covered Harris’s research in the last decade on multibody systems and discrete mechanics, providing a comprehensive overview of his fundamental research contributions spanning his long academic career. The next talk was given by Tony Bloch from the Department of Mathematics at the University of Michigan. In his talk, “The Rolling Sphere and Quantum Spin,” Tony demonstrated an interesting connection between the kinematics of a sphere rolling on a plane and quantum spin. This talk began with

Amit Sanyal.

Anthony Bloch.

Harris McClamroch delivering opening remarks.

OCTOBER 2010

«

IEEE CONTROL SYSTEMS MAGAZINE 81

Harris McClamroch.

Hariharan Krishnan.

a question about how much a sphere rotates when it rolls along a closed planar curve. He showed that this problem can be solved by mapping it to the precession of a spin 1/2 in a magnetic field of variable magnitude and direction. It was also noted that this mapping can be of pedagogical use in discussing both rolling and spin precession and particularly in understanding the emergence of geometrical phases in classical problems. Jessy Grizzle, from the Department of Electrical Engineering and Computer Science at the University of Michigan, presented the next talk, titled “MABEL: A New Robotic Bipedal Walker and Runner.” He summarized recent progress in developing a bipedal robot, named MABEL, which is designed to be both a robust walker and runner. In particular, experimental results for challenging problems,

such as walking on uneven terrain, were illustrated by several interesting videos. He also talked about theoretical difficulties in extending his control results to a three-dimensional bipedal robot model. He showed that motion out of the sagittal plane requires consideration of additional unactuated degrees of freedom and the robot’s natural dynamics account for these degrees of freedom in the method of virtual constraints and hybrid zero dynamics. Ilya Kolmanovsky gave a talk, “On the Interplay Between Modeling, Dynamics, and Control: A Few Examples,” where he presented several examples for dynamics and control of nonholonomic systems he studied with Harris. Ilya showed that controllability of a free-rotating cylinder could be analyzed by applying averaging theory to small-amplitude,

high-frequency motions, which could also be used for constructing openloop maneuvers for general multibody systems. He also presented a switching feedback control algorithm based on a parameter-dependent family of control laws, where switching parameters can be chosen by solving a low-dimensional parameter optimization problem over a finite horizon. Several applications to automotive control systems were shown, including a dual-clutch transmission and a diesel selective catalyst reduction system. His talk concluded with remarks on the importance of the interplay between modeling, dynamics, and control theory. The next talk, titled “Connected Vehicle and Continuous Safety,” was given by Hariharan Krishnan, who is a staff researcher at the Electrical and Controls Integration Laboratory of the General Motors Research and Development Center and a former doctoral student. Hariharan described an adaptive communication scheme for a cooperative active safety system (CASS), which uses information communicated from neighboring vehicles to provide warnings or other forms of assistance to drivers. The information exchange between vehicles includes position, speed, heading, and other vehicle kinematic and dynamic information. This information is broadcast to all neighbors, including pedestrians with hand-held devices, within a certain communication range

Jessy Grizzle.

Taeyoung Lee.

Darren Schumacher.

82 IEEE CONTROL SYSTEMS MAGAZINE

» OCTOBER 2010

so that they can be used to actively evaluate driving situations. The operation of this active safety system was illustrated by several videos. Another former doctoral student, Jinglai Shen, currently a faculty member at the University of Maryland, gave a talk on constrained dynamical systems. He began by describing Harris’s contributions to constrained dynamics with equality constraints such as nonholonomic systems. Jinglai pointed out that Harris also did pioneering research on mechanical systems with contacts described by inequality constraints; these constraints can be expressed in the form of complementarity systems: nonsmooth, multimodal, and switched dynamic systems that belong to the broad framework of hybrid systems. He showed that this class of contact systems could exhibit complex and intricate dynamical phenomena, such as Zeno behavior. He also discussed that complementarity systems have a wide range of applications to constrained optimal control and shape-restricted regression problems in statistics, including estimation of regulatory functions in genetic networks. Taeyoung Lee gave the last presentation of the technical program. In his talk, “Computational Geometric Mechanics and Control of Multibody Systems,” he summarized recent joint

Harris is a former editor-in-chief of IEEE Transactions on Automatic Control and a former president of the IEEE Control Systems Society. work with Melvin Leok of the University of California, San Diego, and Harris dealing with geometric numerical integration of multibody systems and its extension to control and estimation problems. He discussed the importance of structure preservation in the simulation of multibody systems, and he demonstrated desirable computational properties of a particular geometric integrator, referred to as a Lie group variational integrator, for various complex multibody dynamics such as full body systems and tethered rigid bodies. After these technical talks, colleagues and former students made remarks on their experiences in working with Harris. Taeyoung Lee presented messages from former doctoral students, including Chelsea White, chair of Transportation and Logistics at the Georgia Institute of Technology, and Danwei Wang at Nanyang Technological University, Singapore. Then, Melvin Leok recalled some of his inter-

actions and collaborations with Harris. These remarks were followed by remarks from two other former doctoral students, Darren Schumacher, vice president at SPX Corporation, and Chunlei Rui of Northrop Grumman. Chunlei presented several videos about space missions he has been working on based on his doctoral work with Harris, including the James Webb Space Telescope. The symposium attendees included approximately 50 students and faculty members in addition to the technical speakers. The symposium was supported with financial and organizational assistance from Wei Shyy and Lisa Szuma of the Aerospace Engineering Department at the University of Michigan. Ilya Kolmanovsky Taeyoung Lee Amit Sanyal Jinglai Shen Organizers

Call to Action

F

or everywhere we look, there is work to be done. The state of our economy calls for action, bold and swift. And we will act, not only to create new jobs, but to lay a new foundation for growth. We will build the roads and bridges, the electric grids and digital lines that feed our commerce and bind us together. We’ll restore science to its rightful place, and wield technology’s wonders to raise health care’s quality and lower its cost. We will harness the sun and the winds and the soil to fuel our cars and run our factories. And we will transform our schools and colleges and universities to meet the demands of a new age. All this we can do. All this we will do. —Barack Obama, Presidential Inauguration Speech, January 20, 2009.

OCTOBER 2010

«

IEEE CONTROL SYSTEMS MAGAZINE 83