Randy Freeman joined Northwestern in 1996 after receiving his Ph.D. in Electrical Engineering from the University of California at Santa Barbara. He received the NSF CAREER Award in 1997. He has served as Associate Editor of the IEEE Control Systems Society Conference Editorial Board, has served on Program and Operating Committees for the IEEE Conference on Decision and Control and the American Control Conference, and has served as Associate Editor of the IEEE Transactions on Automatic Control and the IEEE Transactions on Control of Network Systems.

Current research interests:

• nonlinear control theory
• robust control, optimal control
• nonlinear system theory
• control and estimation for multi-agent systems

Selected journal publications:

• I.L. Donato Ridgley, R.A. Freeman, and K.M. Lynch, "Private and hot-pluggable distributed averaging," IEEE Control Systems Letters, vol. 4, no. 4, pp. 988–993, Oct. 2020.
• M.L. Elwin, R.A. Freeman, and K.M. Lynch, "Distributed environmental monitoring with finite element robots," IEEE Trans. Robot., vol. 36, no. 2, pp. 380–398, Apr. 2020.
• D.A. Burbano Lombana, R.A. Freeman, and K.M. Lynch, "Distributed inference of the multiplex network topology of complex systems," IEEE Trans. Control Netw. Syst., vol. 7, no. 1, pp. 278–287, Mar. 2020.
• D.A. Burbano Lombana, R.A. Freeman, and K.M. Lynch, "Discovering the topology of complex networks via adaptive estimators," Chaos, vol. 29, no. 8, 2019.
• J. George and R.A. Freeman, "Robust dynamic average consensus algorithms," IEEE Trans. Automat. Contr., vol. 64, no. 11, pp. 4615–4622, Nov. 2019.
• S.S. Kia, B. Van Scoy, J. Cortés, R.A. Freeman, K.M. Lynch, and S. Martínez, "Tutorial on dynamic average consensus: the problem, its applications, and the algorithms," IEEE Control Systems Magazine, vol. 39, no. 3, pp. 40–72, June 2019.
• B. Van Scoy, R.A. Freeman, and K.M. Lynch, "The fastest known globally convergent first-order method for minimizing strongly convex functions," IEEE Control Systems Letters, vol. 2, no. 1, pp. 49–54, Jan. 2018.
• M.L. Elwin, R.A. Freeman, and K.M. Lynch, "Distributed Voronoi neighbor identification from inter-robot distances," IEEE Robotics and Automation Letters, vol. 2, no. 3, pp. 1320–1327, July 2017.
• E. Mallada, R.A. Freeman, and A.K. Tang, "Distributed synchronization of heterogeneous oscillators on networks with arbitrary topology," IEEE Trans. Control Netw. Syst., vol. 3, no. 1, pp. 1–12, March 2016.
• H. Ito, R.A. Freeman, and A. Chaillet, " Revisiting the iISS small-gain theorem through transient plus ISS small-gain regulation," Asian Journal of Control, vol. 15, no. 1, pp. 11–19, Jan. 2013.
• P. Yang, R.A. Freeman, G.J. Gordon, K.M. Lynch, S.S. Srinivasa, and R. Sukthankar, "Decentralized estimation and control of graph connectivity for mobile sensor networks," Automatica, vol. 46, no. 2. pp. 390–396, Feb. 2010.
• P. Yang, R.A. Freeman, and K.M. Lynch, "Multi-agent coordination by decentralized estimation and control," IEEE Trans. Automat. Contr., vol. 53, no. 11. pp. 2480–2496, Dec. 2008.
• K.M. Lynch, I.B. Schwartz, P. Yang, and R.A. Freeman, "Decentralized environmental modeling by mobile sensor networks," IEEE Trans. Robot., vol. 24, no. 3, pp. 710–724, June 2008.
• A. Chen, G.-Q. Chen, and R.A. Freeman, "Stability of nonlinear feedback systems: a new small-gain theorem," SIAM J. Control Optim., vol. 46, no. 6, pp. 1995–2012, Nov. 2007.
• B.E. Miller, J.E. Colgate, and R.A. Freeman, "On the role of dissipation in haptic systems," IEEE Trans. Robot., vol. 20, no. 4, pp. 768–771, Aug. 2004.
• H. Ito and R.A. Freeman, "Uniting local and global controllers for uncertain nonlinear systems: beyond global inverse optimality," Sys. Control Letters, vol. 45, no. 1, pp. 59–79, 2002.
• H. Ito and R.A. Freeman, "State-dependent scaling design for a unified approach to robust backstepping," Automatica, vol. 37, pp. 843–855, 2001.
• B.E. Miller, J.E. Colgate, and R.A. Freeman, "Guaranteed stability of haptic systems with nonlinear virtual environments," IEEE Trans. Robot. Autom., vol. 16, no. 6, pp. 712–719, Dec. 2000.

Selected conference publications:

• I.L. Donato Ridgley, R.A. Freeman, and K.M. Lynch, "Private and hot-pluggable distributed averaging," Proceedings of the 59th IEEE Conference on Decision and Control, (Jeju Island, Republic of Korea), to appear, Dec. 2020.
• I.L. Donato Ridgley, R.A. Freeman, and K.M. Lynch, "Simple, private, and accurate distributed averaging," Proceedings of the 57th Annual Allerton Conference on Communication, Control, and Computing, (Monticello, Illinois), pp. 446–452, Sept. 2019.
• D.A. Burbano Lombana, R.A. Freeman, and K.M. Lynch, "A distributed adaptive observer for leader-follower networks," in Proceedings of the 2019 American Control Conference, (Philadelphia, Pennsylvania), pp. 2722–2727, July 2019.
• D.A. Burbano Lombana, J. George, R.A. Freeman, and K.M. Lynch, "Inferring private information in wireless sensor networks," in Proceedings of the 44th IEEE International Conference on Acoustics, Speech, and Signal Processing, pp. 4310--4314, May 2019.
• R.A. Freeman, "Noncausal Zames-Falb multipliers for tighter estimates of exponential convergence rates," in Proceedings of the 2018 American Control Conference, (Milwaukee, Wisconsin), pp. 2984–2989, June 2018.
• J. George, M.L. Elwin, R.A. Freeman, and K.M. Lynch, "Distributed fault detection and accommodation in dynamic average consensus," in Proceedings of the 2018 American Control Conference, (Milwaukee, Wisconsin), pp. 5019–5024, June 2018.
• D.A. Burbano Lombana, R.A. Freeman, and K.M. Lynch, "Inferring the network topology of interconnected nonlinear units with diffusive couplings," in Proceedings of the 2018 American Control Conference, (Milwaukee, Wisconsin), pp. 3398–3403, June 2018.
• J. George, R.A. Freeman, and K.M. Lynch, "Robust dynamic average consensus algorithm for signals with bounded derivatives," in Proceedings of the 2017 American Control Conference, (Seattle, Washington), pp. 352–357, May 2017.
• M.L. Elwin, R.A. Freeman, and K.M. Lynch, "Environmental estimation with distributed finite element agents," in Proceedings of the 55th IEEE Conference on Decision and Control, (Las Vegas, Nevada), pp. 5918–5924, Dec. 2016.
• B. Van Scoy, R.A. Freeman, and K.M. Lynch, "Feedforward estimators for the distributed average tracking of bandlimited signals in discrete time with switching graph topology," in Proceedings of the 55th IEEE Conference on Decision and Control, (Las Vegas, Nevada), pp. 4284–4289, Dec. 2016.
• B. Van Scoy, R.A. Freeman, and K.M. Lynch, "Design of robust dynamic average consensus estimators," in Proceedings of the 54th IEEE Conference on Decision and Control, (Osaka, Japan), pp. 6269–6275, Dec. 2015.
• B. Van Scoy, R.A. Freeman, and K.M. Lynch, "A fast robust nonlinear dynamic average consensus estimator in discrete time," in Proceedings of the 5th IFAC Workshop on Distributed Estimation and Control in Networked Systems, (Philadelphia, Pennsylvania), pp. 191–196, Sept. 2015.
• B. Van Scoy, R.A. Freeman, and K.M. Lynch, "Exploiting memory in dynamic average consensus," in Proceedings of the 53rd Annual Allerton Conference on Communication, Control, and Computing, (Monticello, Illinois), pp. 258–265, Sept. 2015.
• B. Van Scoy, R.A. Freeman, and K.M. Lynch, "Optimal worst-case dynamic average consensus,", in Proceedings of the 2015 American Control Conference, (Chicago, Illinois), pp. 5324–5329, July 2015.
• M.L. Elwin, R.A. Freeman, and K.M. Lynch, "Worst-case optimal average consensus estimators for robot swarms," in Proceedings of the 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2014), (Chicago, Illinois), pp. 3814–3819, Sep. 2014.
• B. Van Scoy, R.A. Freeman, and K.M. Lynch, "Asymptotic mean ergodicity of average consensus estimators," in Proceedings of the 2014 American Control Conference, (Portland, Oregon), pp. 4696–4701, June 2014.
• M.L. Elwin, R.A. Freeman, and K.M. Lynch, "A systematic design process for internal model average consensus estimators," in Proceedings of the 52nd IEEE Conference on Decision and Control, (Florence, Italy), pp. 5878–5883, Dec. 2013.
• R.A. Freeman, "A global attractor consisting of exponentially unstable equilibria," in Proceedings of the 2013 American Control Conference, (Washington, D.C.), pp. 4862–4867, June 2013.
• F. Morbidi, R.A. Freeman, and K.M. Lynch, "Estimation and control of UAV swarms for distributed monitoring tasks," in Proceedings of the 2011 American Control Conference, (San Francisco, California), pp. 1069–1075, June 2011.
• H. Bai, R.A. Freeman, and K.M. Lynch, "Distributed Kalman filtering using the internal model average consensus estimator," in Proceedings of the 2011 American Control Conference, (San Francisco, California), pp. 1500–1505, June 2011.
• H. Ito, R.A. Freeman, and A. Chaillet, "Interpreting the iISS small-gain theorem as transient plus ISS small-gain regulation," in Proceedings of the 49th IEEE Conference on Decision and Control, (Atlanta, Georgia), pp. 2432–2437, Dec. 2010.
• H. Bai, R.A. Freeman, and K.M. Lynch, "Robust dynamic average consensus of time-varying inputs," in Proceedings of the 49th IEEE Conference on Decision and Control, (Atlanta, Georgia), pp. 3104–3109, Dec. 2010.
• R.A. Freeman, T.R. Nelson, and K.M. Lynch, "A complete characterization of a class of robust linear average consensus protocols," Proceedings of the 2010 American Control Conference, Baltimore, Maryland, pp. 3198–3203, June 2010.
• T.R. Nelson and R.A. Freeman, "Set-valued estimation for mobile sensor networks," Proceedings of the 48th IEEE Conference on Decision and Control, Shanghai, China, pp. 2681–2686, Dec. 2009.
• T.R. Nelson and R.A. Freeman, "Decentralized H_∞ filtering in a multi-agent system," Proceedings of the 2009 American Control Conference, St. Louis, Missouri, pp. 5755–5760, June 2009.
• P. Yang, R.A. Freeman, G.J. Gordon, K.M. Lynch, S.S. Srinivasa, and R. Sukthankar, "Decentralized estimation and control of graph connectivity in mobile sensor networks," Proceedings of the 2008 American Control Conference, Seattle, Washington, pp. 2678–2683, June 2008.
• P. Yang, R.A. Freeman, and K.M. Lynch, "A general stability condition for multi-agent coordination by coupled estimation and control," Proceedings of the 2007 American Control Conference, New York, pp. 723–728, July 2007.
• P. Yang, R.A. Freeman, and K.M. Lynch, "Distributed cooperative active sensing using consensus filters," Proceedings of the IEEE Int. Conf. Robotics and Automation, Rome, Italy, pp. 405–410, Apr. 2007.
• R.A. Freeman, P. Yang, and K.M. Lynch, "Stability and convergence properties of dynamic average consensus estimators," Proceedings of the 45th IEEE Conference on Decision and Control, San Diego, California, pp. 398–403, Dec. 2006.
• R.A. Freeman, P. Yang, and K.M. Lynch, "Distributed estimation and control of swarm formation statistics," Proceedings of the 2006 American Control Conference, Minneapolis, Minnesota, pp. 749–755, June 2006.
• P. Yang, K.M. Lynch, and R.A. Freeman, "Optimal information propagation in sensor networks," Proceedings of the 2006 IEEE International Conference on Robotics and Automation, Orlando, Florida, pp. 3122–3127, May 2006.
• A. Chen, G.-Q. Chen, and R.A. Freeman, "Conditional gain is necessary and sufficient for the robust stabilization of nonlinear systems," in Proceedings of the 43rd IEEE Conference on Decision and Control, Paradise Island, Bahamas, pp. 1347–1351, Dec. 2004.
• R.A. Freeman, "On the relationships between induced l_∞-gain and various notions of dissipativity" in Proceedings of the 43rd IEEE Conference on Decision and Control, Paradise Island, Bahamas, pp. 3430–3434, Dec. 2004.
• R.A. Freeman, "On the necessity of the small-gain theorem in the performance analysis of nonlinear systems," in Proceedings of the 40th IEEE Conference on Decision and Control, Orlando, Florida, pp. 51–56, Dec. 2001.
• R.A. Freeman, "On the necessity of the small-gain theorem for nonlinear systems without fading memory," in Proceedings of the 39th Annual Allerton Conference on Communication, Control, and Computing, Monticello, Illinois, pp. 1225–1233, Oct. 2001.
• B.E. Miller, J.E. Colgate, and R.A. Freeman, "Environment delay in haptic systems," in Proceedings of the 2000 IEEE International Conference on Robotics and Automation, San Francisco, California, pp. 2434–2439, 2000.
• B.E. Miller, J.E. Colgate, and R.A. Freeman, "Framework for the design of stable haptic systems," in Proceedings of the World Automation Conference ISORA, Maui, Hawaii, 2000.
• V. Rawls and R.A. Freeman, "Comparison of receding horizon control and an adaptive approach to cost reduction using Lyapunov design in nonlinear systems," in Proceedings of the 2000 American Control Conference, Chicago, Illinois, pp. 265–269, June 2000.
• V. Rawls and R.A. Freeman, "Adaptive minimum-cost Lyapunov-descent control of nonlinear systems," in Proceedings of the 2000 American Control Conference, Chicago, Illinois, pp. 1649–1653, June 2000.