This paper proposes a new stability analysis for the Reaction Torque Observer (RTOb) based robust force control systems in the discrete-time domain. The robust force controller is implemented by employing a Disturbance Observer (DOb) to suppress disturbances, such as friction and hysteresis, in an inner-loop and another disturbance observer, viz RTOb, to estimate contact forces without using a force sensor. Since the RTOb-based robust force controllers are always implemented using computers and/or microcontrollers, this paper proposes a stability analysis in the discrete-time domain. It is shown that the bandwidth of the DOb is limited not only by the noise of velocity measurement but also by the waterbed effect. It is also shown that the stability of the robust force controller may significantly deteriorate when the design parameters of the RTOb are not properly tuned. For example, the robust force controller may have a non-minimum phase zero(s) as the design parameter of the identified inertia (torque coefficient) of the RTOb is increased (decreased). This may lead to poor stability and performance in force control applications. The proposed stability analysis conducted in the discrete-time domain is verified by simulations and experiments.
An Improved Adaptive Smo for Speed Estimation of Sensorless Dsfoc Induction Motor Drives and Stability Analysis using Lyapunov Theorem at Low Frequencies
A Sliding Mode Control for a Sensorless Tracker: Application on a Photovoltaic System
Advanced System Laboratory, Polytechnic School of Tunisia（突尼斯高等理工学院高级系统实验室）；Department of Electronic, High Institute of Applied Sciences and Technologies, Sousse, Tunisia（苏塞应用科学和技术高等理工学院电子系）
Design and Experimental Validation of Sensorless 4-Channel Bilateral Teleoperation for Low-Cost Manipulators
Degree Programs in Intelligent and Mechanical Interaction Systems, University of Tsukuba（智能与机械交互系统专业，东京大学）；Faculty of Engineering, Information and Systems, University of Tsukuba（工程、信息与系统学部，东京大学）；Department of Electrical Engineering, Electronics, and Applied Physics, Saitama University（电子工程、电子学与应用物理系，埼玉大学）
Neuromechanical model-based adaptive control of bi-lateral ankle exoskeletons: biological joint torque and electromyogram reduction across walking conditions
Accurate Control under Voltage Drop for Rotor Drones
Beihang University（北京航空航天大学）；School of Aeronautic Science and Engineering, Beihang University（北京航空航天大学航空科学与工程学院）；School of Automation Science and Electrical Engineering, Beihang University（北京航空航天大学自动化科学与电气工程学院）；School of Cyber Science and Technology, Beihang University（北京航空航天大学网络空间科学与技术学院）；Hangzhou Innovation Institute, Beihang University（北京航空航天大学杭州创新研究院）
Position Sensor-less and Adaptive Speed Design for Controlling Brush-less DC Motor Drives
School of Electrical and Computer Engineering, University of Tabriz（大不里士大学电气与计算机工程学院）；School of Electrical Engineering and Computer Science, Queensland University of Technology（昆士兰科技大学电气与计算机工程学院）；School of Electrical and Computer Engineering University of North Carolina at Charlotte（北卡罗来纳大学夏洛特分校电气与计算机工程学院）；School of Electrical and Electronics Engineering, Shiraz University of Technology（设拉子理工大学电气与电子工程学院）
Cooperative Switched Formation Control of Autonomous Vehicles: An Event-triggered Approach to Input Saturation and Time-delay Challenges
The Hong Kong University of Science and Technology (Guangzhou)（香港科技大学（广州））；The Hong Kong University of Science and Technology（香港科技大学）；KTH Royal Institute of Technology（皇家理工学院）
Robust Adaptive Safe Robotic Grasping with Tactile Sensing
Maersk Mc-Kinney Moller Institute, University of Southern Denmark（马士基麦金尼默勒研究所，丹麦南方大学）；Departments of Mechanical and Civil Engineering and Computing and Mathematical Sciences , California Institute of Technology（机械与土木工程系和计算与数学科学系，加州理工学院）
