Publications

Recent Papers

1. Joshi, K., Liu, T., & Chopra, N. (2025) Cascade IPG Observer for Underwater Robot State Estimation. IEEE International Conference on Robotics and Automation (ICRA 2025) [arxiv] [pdf]

2. Joshi, K., Liu, T., Williams, A., Gray, M., Lin, X., & Chopra, N. (2024). 3D Water Quality Mapping using Invariant Extended Kalman Filtering for Underwater Robot Localization. IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2024): Workshop on Autonomous Robotic Systems in Aquaculture: Research Challenges and Industry Needs [pdf] [poster]

3. Srinivasan, D., Beyer, A., Zhu, D., Churchill, S., Mehta, K., Sridhar, S. K.,  Chakrabarti, K., Steuerman, D.W., Chopra, N. & Dutt, A. (2024). Trapped-ion quantum simulation of the Fermi-Hubbard model as a lattice gauge theory using hardware-aware native gates.[pdf]

Books

Book Chapters

1. Hatanaka, T., Chopra, N., Yamauchi, J., & Fujita, M. (2017). A Passivity-Based Approach to Human–Swarm Collaboration and Passivity Analysis of Human Operators. In Trends in Control and Decision-Making for Human–Robot Collaboration Systems (pp. 325-355). Springer International Publishing.

2. N. Chopra and M.W. Spong, “Output Synchronization of Nonlinear Systems with Relative Degree One,”  In Recent Advances in Learning and Control, V.D. Blondel, S.P. Boyd, H. Kimura (Eds.), Lecture Notes in Control and Information Sciences, Springer-Verlag, pp. 51-64, 2008.

3. M.W. Spong and N. Chopra, “Synchronization of Networked Lagrangian Systems,” In Lagrangian and Hamiltonian Methods for Nonlinear Control 2006,  F. Bullo and K. Fujimoto (Eds.),  Lecture Notes in Control and Information Sciences, Vol. 366, Springer Verlag, pp. 47-59, 2007.

4. N. Chopra and M.W. Spong, “Adaptive Synchronization of Bilateral Teleoperators with Time Delay,” In Advances in Telerobotics: Human Interfaces, Control, and Applications, M. Ferre, M. Buss, R. Aracil, C. Melchiorri and C. Balaguer (Eds.), Springer, STAR series, pp. 257-270, 2007.

5. N. Chopra and M.W. Spong, “Passivity-Based Control of Multi-Agent Systems,” In Advances in Robot Control, From Everyday Physics to Human-Like Movements, Sadao Kawamura and Mikhail Svinin, Eds., pp. 107-134, Springer-Verlag, Berlin, 2006.

6. N. Chopra, M.W. Spong, R. Ortega, and N.E. Barabanov, “Position and Force Tracking in Bilateral Teleoperation,” Lecture Notes in Control and Information Sciences, Vol. 308, Springer Verlag, Berlin, pp. 269-280, 2004.

Journal Articles

1.     T. Hatanaka, T. Mochizuki, T. Sumino, J. M. Maestre and N. Chopra, "Human Modeling and Passivity Analysis for Semi-Autonomous Multi-Robot Navigation in Three Dimensions," in IEEE Open Journal of Control Systems, Vol. 3, pp. 45-57, 2024.

2.     K. Chakrabarti, and N. Chopra, “A Control Theoretic Framework for Adaptive Gradient Optimizers,” Automatica, 2024, Volume 160, February 2024, 111466.

3.     J. N. Twigg, F. Dagefu, N. Chopra and B. M. Sadler, “Robotic Parasitic Arrays for Increased RSS in Non-Line-of-Sight,” IEEE Robotics and Automation Letters, Vol. 7, no. 4, pp. 9167-9174, Oct. 2022.

4.     N. Chopra, M. Fujita, R. Ortega and M. W. Spong, “Passivity-Based Control of Robots: Theory and Examples from the Literature,” IEEE Control Systems Magazine, Vol. 42, No. 2, pp. 63-73, 2022.

5.     K. Chakrabarti, N. Gupta and N. Chopra, “On Preconditioning of Decentralized Gradient-Descent When Solving a System of Linear Equations,” IEEE Transactions on Control of Network Systems, Vol. 9, No. 2, pp. 811-822, 2022.

6.     K. Chakrabarti, N. Gupta, and N. Chopra, “Iterative Pre-Conditioning for Expediting the Gradient-Descent Method: The Case of Distributed Linear Least-Squares Problem,” Automatica, Vol. 137, 110095, 2022.

7.     K. Chakrabarti, N. Gupta, and N. Chopra, “Robustness of Iteratively Pre-Conditioned Gradient-Descent Method: The Case of Distributed Linear Regression Problem,” IEEE Control Systems Letters, 5(6), pp. 2180-2185, 2020.

8.     N. Gupta, S. Gade, N. Chopra, and N.H. Vaidya, “Preserving statistical privacy in distributed optimization,” IEEE Control Systems Letters, 5(3), pp. 779-784, 2020.

9.     T. Liu, S. Azarm, N. Chopra, “Decentralized Multisubsystem Co-Design Optimization Using Direct Collocation and Decomposition-Based Methods. Journal of Mechanical Design, 142(9), 2020.

10.   J. N. Twigg, N. Chopra and B. M. Sadler, “Communication Maintenance of Robotic Parasitic Antenna Arrays,” IEEE Robotics and Automation Letters, vol. 5, no. 4, pp. 6475-6482, Oct. 2020.

11.   T. Liu, S. Azarm, N. Chopra, “Integrating Optimal Vehicle Routing and Control With Load-Dependent Vehicle Dynamics Using a Confidence Bounds for Trees-Based Approach." Journal of Dynamic Systems, Measurement, and Control 142.4, 2020.

12.   Y. Dong and N. Chopra, “Passivity-Based Bilateral Tele-Driving System with Parametric Uncertainty and Communication Delays,” IEEE Control Systems Letters, Vol. 3, No. 2, pp. 350-355, 2019.

13.   Y. Dong, N. Gupta, and N. Chopra, “False Data Injection Attacks in Bilateral Teleoperation Systems,” IEEE Transactions on Control Systems Technology, Vol. 28, No. 3, pp. 1168-1176, 2020. 

14.   T. Hatanaka, N. Chopra, T. Ishizaki, and N. Li, “Passivity Based Distributed Optimization with Communication Delays using PI Consensus Algorithm,” IEEE Transactions on Automatic Control, Vol. 63, No. 12, 2018.

15.   M.W.S. Atman, T. Hatanaka, Z. Qu, N. Chopra, J. Yamauchi, and M. Fujita, “Human-enabled Motion Synchronization for Semi-Autonomous Robotic Swarm with a Passivity-short Human Operator," International Journal of Intelligent Robotics and Applications, Vol. 2, No. 2, pp. 235- 251, 2018.

16.    P.V.  Chanekar, N. Chopra, and S. Azarm, “Co-design of Linear Systems using Generalized Benders Decomposition,” Automatica, Vol. 89, pp. 180-193, 2018.

17.   T. Liu, S. Azarm, N. Chopra, “On Decentralized Optimization for a Class of Multisubsystem Codesign Problems,” ASME Journal of Mechanical Design, Vol. 139, No. 12, pp. 121404-11, 2017. 

18.   T. Hatanaka, N. Chopra, J. Yamauchi, M. Doi, Y. Kawai, M. Fujita, “A Passivity-Based System Design of Semi-Autonomous Cooperative Robotic Swarm,” ASME. Mechanical Engineering, Vol. 139, No. 06, pp. S14-S18, 2017.

19.   Y. Dong, N. Gupta, and N. Chopra, “Content modification attacks on consensus seeking multi-agent system with double-integrator dynamics,” Chaos: An Interdisciplinary Journal of Nonlinear Science 26.11 (2016): 116305. 

20.   L. Sabattini, C. Secchi, N. Chopra, “Decentralized Estimation and Control for Preserving the Strong Connectivity of Directed Graph,” IEEE Transactions on Cybernetics, Vol. 45, No. 10, pp. 2273-2286, Oct. 2015.

21.   L. Sabattini, C. Secchi, N. Chopra, “Decentralized Connectivity Maintenance for Networked Lagrangian Systems with Collision Avoidance,” Asian Journal of Control, Vol. 17, No. 1, pp. 111-123, Jan. 2015.  

22.   P. Tallapragada and N. Chopra, “Decentralized Event-Triggering for Control of Nonlinear Systems,” IEEE Transactions on Automatic Control, Vol. 59, No. 12, pp. 3312-3324, 2014.

23.   Y-C. Liu and N. Chopra, “Gravity Compensation Driven Position Regulation for Robotic Systems under Input-Output Delays,” IEEE Transactions on Control Systems Technology, Vol. 22, No.3, pp. 995-1005, 2014.

24.    Y-C. Liu and N. Chopra, “On Stability and Regulation Performance for Flexible-Joint Robots with Input/Output Communication Delays,” Vol. 50, No. 6, Automatica, pp. 1698-1705, 2014.

25.   L. Sabattini*, N. Chopra, and C. Secchi, “Decentralized Connectivity Maintenance for Cooperative Control of Mobile Robotic Systems,” International Journal of Robotics Research, Vol. 32, No.12, pp. 1411-1423, 2013.

26.   L. Sabattini*, C. Secchi, N. Chopra, and A. Gasparri, “Distributed Control of Robotic Systems with Global Connectivity Maintenance,” IEEE Transactions on Robotics, Vol. 29, No. 5, pp. 1326-1332, 2013.

27.   Y-C. Liu and N. Chopra, “Synchronization of Networked Mechanical Systems with Communication Delays and Human Input,” ASME Journal of Dynamic Systems, Measurement, and Control, Vol. 135, No. 4, 2013.

28.   P. Tallapragada and N. Chopra, “On Event-Triggered Tracking for Nonlinear Systems,” IEEE Transactions on Automatic Control, Vol. 58, No. 9, pp. 2343-2348, 2013

29.   Y-C. Liu and N. Chopra, “Control of Semi-Autonomous Teleoperation System with Time Delays,” Automatica, Vol. 49, No. 6, pp. 1553-1565, 2013.

30.   N. Chopra, “Output Synchronization on Strongly Connected Graphs,” IEEE Transactions on Automatic Control, Vol. 57, No. 11, pp. 2896-2901, 2012.

31.   Y-C. Liu and N. Chopra, “Control of Robotic Manipulators under Input-Output Communication Delays: Theory and Experiments,” IEEE Transactions on Robotics, Vol. 28, No. 3, pp. 742-751, 2012.

32.   Y-C. Liu and N. Chopra, “Controlled Synchronization of Robotic Manipulators in the Task Space,” IEEE Transactions on Robotics, Vol. 28, No. 1, pp. 268-275, 2012.

33.   N. Chopra and M.W. Spong, “On Exponential Synchronization of Kuramoto Oscillators,” IEEE Transactions on Automatic Control, Vol. 53, No. 4, 2009.

34.    N. Chopra, M.W. Spong, and R. Lozano, “Synchronization of Bilateral Teleoperators with Time Delay,” Automatica, Vol. 44, No. 8, pp. 2142-2148, 2008.

35.   N. Chopra, P. Berestesky and M.W. Spong, “Bilateral Teleoperation Over Unreliable Communication Networks,” IEEE Transactions on Control Systems Technology, Vol.16, No. 2, pp. 304-313, 2008.

36.   N.  Chopra, M.W. Spong, R. Ortega, and N.E. Barabanov, “On Tracking Performance in Bilateral Teleoperation,” IEEE Transactions on Robotics, Vol. 22, pp. 861-866, 2006.

Conference Publications

1.     T. Liu, K. Chakrabarti and N. Chopra, "Accelerating the Iteratively Preconditioned Gradient-Descent Algorithm using Momentum," 2023 Ninth Indian Control Conference (ICC), Visakhapatnam, India, 2023, pp. 68-73.

2. D. Srinivasan, K. Chakrabarti, N. Chopra and A. Dutt, "Quantum Circuit Optimization through Iteratively Pre-Conditioned Gradient Descent," 2023 IEEE International Conference on Quantum Computing and Engineering (QCE), Bellevue, WA, USA, 2023, pp. 443-449.

3.  T. Liu, K. Chakrabarti and N. Chopra, "Iteratively Preconditioned Gradient-Descent Approach for Moving Horizon Estimation Problems," 2023 62nd IEEE Conference on Decision and Control (CDC), Singapore, Singapore, 2023, pp. 8457-8462.  

4.  K. Chakrabarti and N. Chopra, "IPG Observer: A Newton-Type Observer Robust to Measurement Noise," 2023 American Control Conference (ACC), San Diego, CA, USA, 2023, pp. 3069-3074.

5. K. Chakrabarti and N. Chopra, "A State-Space Perspective on the Expedited Gradient Methods: Nadam, RAdam, and Rescaled Gradient Flow," 2022 Eighth Indian Control Conference (ICC), Chennai, India, 2022, pp. 31-36.

6. K. Chakrabarti and N. Chopra, "Analysis and Synthesis of Adaptive Gradient Algorithms in Machine Learning: The Case of AdaBound and MAdamSSM," 2022 IEEE 61st Conference on Decision and Control (CDC), Cancun, Mexico, 2022, pp. 795-800.

7.  L. Weerakoon and N. Chopra, "Passivity-Based Task Space Control of Hybrid Rigid-Soft (HyRiSo) Robots with Parametric Uncertainty," 2022 IEEE 61st Conference on Decision and Control (CDC), Cancun, Mexico, 2022, pp. 771-776, 

8. T. Liu, N. Chopra, and J. Samtani, “Information System for Detecting Strawberry Fruit Locations and Ripeness Conditions in a Farm,” In Biol. Life Sci. Forum (Vol. 2), 2022.

9.  L. Weerakoon and N. Chopra, “Swing up Control of a Soft Inverted Pendulum with Revolute Base,” IEEE Conference on Decision and Control, 2021, pp. 685-690.

10.  K. Chakrabarti and N. Chopra, “Generalized AdaGrad (G-AdaGrad) and Adam: A State-Space Perspective,” IEEE Conference on Decision and Control, 2021, pp. 1496-1501.

11. L. Weerakoon, Z. Ye, R.S. Bama E. Smela, M. Yu and N. Chopra, “Adaptive Tracking Control of Soft Robots using Integrated Sensing Skin and Recurrent Neural Networks,” In International Conference on Robotics and Automation,” 2021, pp. 12170-12176.

12. K. Chakrabarti, N. Gupta, and N. Chopra, “Accelerating Distributed SGD for Linear Regression using Iterative Pre-Conditioning,” In Learning for Dynamics and Control, PMLR, 2021, pp. 447-458.

13. K. Chakrabarti, N. Gupta, and N. Chopra “Robustness of the iteratively preconditioned gradient descent method:  The case of distributed linear regression problem,” American Control Conference, 2021, pp. 2248-2253,

14.  K. Chakrabarti, N. Gupta, and N. Chopra, “Iterative pre-conditioning to expedite the gradient-descent method,” American Control Conference, 2020, pp. 3977-3982.

15. L. Weerakoon and N. Chopra, “Bilateral teleoperation of soft robots under piecewise constant curvature hypothesis: An experimental investigation,” American Control Conference, pp. 2124-2129, 2020.

16.  K. Chakrabarti, N. Gupta. and N. Chopra, “On Distributed Solution of Ill-Conditioned System of Linear Equations under Communication Delays,” Sixth Indian Control Conference, pp. 413-418, 2019.

17.  N. Gupta, J. Katz, and N. Chopra, “Statistical Privacy in Distributed Average Consensus on Bounded Real Inputs,” In Proceedings of the American Control Conference, 2019, pp. 1836-1841.

18. N. Gupta and N. Chopra, “Model-Based Encryption: Privacy of States in Networked Control Systems," 2018 56th Annual Allerton Conference on Communication, Control, and Computing (Allerton), Monticello, IL, USA, 2018, pp. 242-248.

19. T. Liu, S. Azarm, and N. Chopra, “Integrating Multi-Vehicle Routing and Control: A Comparison of Three Solution Strategies,” ASME. International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Volume 3: 20th International Conference on Advanced Vehicle Technologies; 15th International Conference on Design Education, 2018.

20.  P. V. Chanekar, N. Chopra and S. Azarm, “Optimal Structured Static Output Feedback Design using Generalized Benders Decomposition,” In Proceedings of IEEE Conference on Decision and Control, Melbourne, Australia, 2017, pp. 4819-4824.

21. N. Gupta, J. Katz, and N. Chopra, “Privacy in Distributed Average Consensus,” IFAC, 2017.

22. J. Yamauchi, M. W. S. Atman, T. Hatanaka, N. Chopra and M. Fujita, "Passivity-based control of human-robotic networks with inter-robot communication delays and experimental verification," 2017 IEEE International Conference on Advanced Intelligent Mechatronics (AIM), Munich, 2017, pp. 628-633.  doi: 10.1109/AIM.2017.8014087

23. T. Liu, S. Azarm S, N. Chopra, “A Decentralized Approach for Multi-Subsystem Co-Design Optimization Using Direct Collocation Method,” ASME. International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Volume 2A: 43rd Design Automation Conference ():V02AT03A004. doi:10.1115/DETC2017-67906.

24. P. V. Chanekar, N. Chopra and S. Azarm, "Optimal actuator placement for linear systems with limited number of actuators," 2017 American Control Conference (ACC), Seattle, WA, 2017, pp. 334-339. doi: 10.23919/ACC.2017.7962975

25. N. Gupta, Yimeng Dong and N. Chopra, "Robustness of distributive double-integrator consensus to loss of graph connectivity," 2017 American Control Conference (ACC), Seattle, WA, 2017, pp. 4516-4521. doi: 10.23919/ACC.2017.7963651

26. N. Gupta and N. Chopra. "Confidentiality in distributed average information consensus." Decision and Control (CDC), 2016 IEEE 55th Conference on. IEEE, 2016.

27. T Liu , S. Azarm, and N. Chopra. "On Decentralized Optimization for a Class of Multi-Subsystem Co-Design Problems." ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016.

28. Y Dong, N. Gupta and N. Chopra, "On content modification attacks in bilateral teleoperation systems," 2016 American Control Conference (ACC), Boston, MA, 2016, pp. 316-321.

29. N. Gupta and N. Chopra, “Stability Analysis of a Two-Channel Feedback Networked Control System,” In Proceedings of the Indian Control Conference, 2016.

30. P. Chanekar, N. Chopra, and S. Azarm, “A New Formulation for Co-Design of Linear Systems with System Matrices Having Affine Design Variables,” In Proceedings of the Indian Control Conference, 2016.

31. T. Hatanaka, N. Chopra, and M. Fujita, “Passivity-based Bilateral Human-Swarm-Interactions for Cooperative Robotic Networks and Human Passivity Analysis,” In Proceedings of the IEEE Conference on Decision and Control, 2015.

32. P. Tallapragada and N. Chopra, “Event-triggered dynamic output feedback control of LTI systems over Sensor-Controller-Actuator Networks,” In Proceedings of the IEEE Conference on Decision and Control, 2013.

33. Y-C Liu and N. Chopra, “Position regulation of flexible-joint robots with input/output constant delays," In Proceedings of IEEE Conference on Intelligent Robots and Systems, 2013.

34. P. Tallapragada and N. Chopra, “Decentralized event-triggering for control of LTI systems,” In Proceedings of IEEE Conference on Control Applications, 2013.

35. L. Sabattini, A. Gasparri, C. Secchi, and N. Chopra, “Decentralized control for maintenance of strong connectivity for directed graphs," In Proceedings of IEEE Conference on Control & Automation, 2013.

36. P. Tallapragada and N. Chopra, “Event-Triggered Dynamic Output Feedback Control for LTI Systems,” In Proceedings of the IEEE Conference on Decision and Control, Maui HI, 10-13 Dec. 2012.

37. P. Tallapragada and N. Chopra, “Event-Triggered Decentralized Dynamic Output Feedback Control for LTI Systems,” In Proceedings of the 3rd IFAC Workshop on Estimation and Control of Networked Systems, Santa Barbara  CA, 15-16 Sep. 2012.

38. Y-C Liu and N. Chopra, “Set-point Control with Gravity Compensation for Robots with Input-Output Delays,” In Proceedings of the ASME Dynamic Systems and Control Conference, Fort Lauderdale FL, Oct. 17-19, 2012.

39. L. Sabattini, A. Gasparri, C. Secchi, and N. Chopra, “Enhanced Connectivity Maintenance for Multi-Robot Systems,” In Proceedings of the 10th IFAC Symposium on Robot Control, Dubrovnik Croatia, 5-7 Sept. 2012.

40. P. Tallapragada and N. Chopra, “Lyapunov Based Sampling for Adaptive Tracking Control in Robot Manipulators,” In Proceedings of the 13th International Symposium on Experimental Robotics, Quebec City Canada, 17-21 June 2012.

41. P. Tallapragada and N. Chopra, “Co-design of Event Trigger and Quantizer for Emulation Based Control,” In Proceedings of the American Control Conference, Montreal Canada, 27-29 June 2012.

42. L. Sabattini, C. Secchi, and N. Chopra, “Decentralized Connectivity Maintenance for Networked Lagrangian Systems,” In Proceedings of the IEEE International Conference on Robotics and Automation, St. Paul MN, 14-18 May 2012, pp. 2433 - 2438.

43. L. Sabattini, N. Chopra, and C. Secchi, “Distributed Control of Multi-Robot Systems with Global Connectivity Maintenance,” In Proceedings of the IEEE International Conference on Intelligent Robots and Systems, San Francisco CA, 25-30 Sep. 2011, pp. 2321 - 2326.

44. Y-C. Liu and N. Chopra, “Semi-Autonomous Teleoperation in Task Space with Redundant Slave Robot under Communication Delays,” In Proceedings of the IEEE International Conference on Intelligent Robots and Systems, San Francisco CA, 25-30 Sep. 2011, pp. 679 - 684.

45. L. Sabattini, N. Chopra, and C. Secchi, “Decentralized Connectivity Maintenance for Mobile Robotic Systems,” To Appear in IEEE Conference on Decision and Control, 2011.

46. P. Tallapragada and N. Chopra, “On Event Triggered Trajectory Tracking for Control Affine Nonlinear Systems,”  To Appear in IEEE Conference on Decision and Control, 2011.

47. Y-C. Liu and N. Chopra, “A New Architecture for Set-Point Control of Robotic Systems with Time-Varying Input-Output Delays,”  To Appear in ASME Dynamics Systems and Control Conference, 2011.

48. N. Chopra, “On Ultimate Boundedness of Delay-Synchronization Algorithms for Semi-Passive Systems,” Allerton Conference on Communication, Control, and Computing, 2010.

49. Y-C. Liu and N. Chopra, “Control of Robotic Manipulators with Input-Output Delays,” In International Symposium on Experimental Robotics, 2010.

50. Y-C. Liu and N. Chopra, “Synchronization of Networked Robotic Systems on Strongly Connected Graphs,” IEEE Conference on Decision and Control, 2010.

51. N. Chopra, “Control of Robotic Manipulators with Time-Varying Sensing-Actuation Delays,” IEEE Conference on Robotics and Automation, 2010.

52. Y-C. Liu and N. Chopra, “On Robust Controlled Synchronization of Interconnected Mechanical Systems,” American Control Conference, 2010.

53. N. Kottenstette and N. Chopra, “Lm_2-stable digital control networks for multiple continuous time passive systems,” 1st IFAC Workshop on Estimation and Control of Networked Systems, 2009  

54. N. Chopra, “Control of Robotic Systems with Input-Output Delays,”  American Control Conference, 2009.

55. N. Chopra, “Passivity Results for Interconnected  Systems with Time Delay,” IEEE Conference on Decision and Control, 2008.

56. R. Lozano, M.W. Spong, J.A. Guerrero, N. Chopra, “Controllability and Observability of Leader-Based Multi-Agent Systems,” IEEE Conference on Decision and Control, 2008.

57. N. Chopra and Y. Liu, “Controlled Synchronization of Mechanical Systems,” ASME Dynamics Systems and Control Conference, 2008.

58. N. Chopra and M.W Spong, “Output Synchronization on Strongly Connected Graphs,” MTNS, 2008.

59. N. Chopra, D. M. Stipanović, and M. W. Spong, “On Synchronization and Collision Avoidance for Mechanical Systems,” American Control Conference,  pp. 3713-3718, 2008.

60. N. Chopra and M.W. Spong, “Delay-independent Stability for Interconnected Nonlinear Systems with Finite L2 Gain,” IEEE Conference on   Decision and Control, pp. 3847-3852, 2007.

61. R. Lozano, N. Chopra, and M.W. Spong, “Convergence Analysis of Bilateral Teleoperation with Constant Human Input,” American Control Conference, pp. 1443-1448, 2007.

62. N. Chopra and M. W. Spong, “Output Synchronization of Nonlinear Systems with Time Delay in Communication,” IEEE Conference on  Decision and Control, pp. 4986-4982, 2006.

63. N. Chopra and M.W. Spong, “On Synchronization of Kuramoto Oscillators,” IEEE Conference on Decision and Control, pp. 3916-3922, 2005. cdc05_Chopra.pdf

64. N. Chopra and M. W. Spong, “On Synchronization of Networked Passive Systems with Time Delays and Application to Bilateral Teleoperation,” Annual Conference of Society of Instrument and Control Engineers of Japan, Okayama, Japan, 2005. sice05.pdf

65. N. Chopra, M.W. Spong, and R. Lozano, “Adaptive Coordination Control of Bilateral Teleoperators with Time Delay,”  IEEE Conference on Decision and Control, pp. 4540-4547, 2004.

66. N. Chopra, M.W. Spong, R. Ortega, and N.E. Barabanov, “On Position Tracking in Bilateral   Teleoperation,” American Control Conference, pp. 5244-5249, 2004.

67. P. Berestesky, N. Chopra, and M.W. Spong, “Discrete Time Passivity in Bilateral Teleoperation over the Internet,” IEEE Conference on Robotics and Automation, pp. 4557-4564, 2004.

68. P. Berestesky, N. Chopra, and M.W. Spong, “Theory and Experiments in Bilateral Teleoperation over the Internet,” IEEE Conference on Control Applications, pp. 456-463, 2004.

69. N. Chopra, M.W. Spong, S. Hirche, and M. Buss, “Bilateral Teleoperation over the Internet: The Time Varying Delay Problem,” American Control Conference, pp. 155-160, 2003.

70. R. Lozano, N. Chopra, and M.W. Spong, “Passivation of Force Reflecting Bilateral Teleoperators with Time Varying Delay,” Mechatronics'02,  Entschede, Netherlands,  2002.