This paper demonstrates the feasibility of using the Action-Reaction principle in order to identify and observe dynamical system parameter and states respectively by considering the instantaneous system's reaction to an imposed action as a natural feedback from the system. System parameters, dynamics and environmental interaction forces or torques are coupled in this incident natural feedback signal. Therefore, success to determine such natural feedback along with decoupling each of the previous information makes it possible to keep dynamical system free from any attached sensors that in turn implies the possibility of performing motion, vibration and force control assignments through measurement taken from the interface point of the actuator with the dynamical system. Both lumped and distributed flexible system are investigated then experiments are performed on a flexible system with two flexible modes then the possibility of extending the work to systems with infinite modes is discussed.

In this paper motion control systems with delay in measurement and control channels are discussed and a new structure of the observer-predictor is proposed. The feature of the proposed system is enforcement of the convergence in both the estimation and the prediction of the plant output in the presence of the variable, unknown delay in both measurement and in the control channels. The estimation is based on the available data — undelayed control input, the delayed measurement of position or velocity and the nominal parameters of the plant and it does not require apriori knowledge of the delay. The stability and convergence is proven and selection of observer and the controller parameters is discussed. Experimental results are shown to illustrate the theoretical predictions.

Induction motor speed sensorless torque control, which allows operation at low and zero speed, optimizing both torque response and efficiency, is proposed. The control is quite different than the conventional field-oriented or direct torque controls. A new discontinuous stator current FPGA based controller and rotor flux observer based on sliding mode and Lyapunov theory are developed, analyzed and experimentally verified. A smooth transition into the field weakening region and the full utilization of the inverter current and voltage capability are possible. The reference tracking performance of speed and rotor flux is demonstrated in terms of transient characteristics by experimental results.

This work attempts to achieve motion control along with vibration suppression of flexible systems by developing a sensorless closed loop LQR controller. Vibration suppression is used as a performance index that has to be minimized so that motion control is achieved with zero residual vibration. An estimation algorithm is combined with the regular LQR to develop sensorless motion and vibration controller that is capable of positioning multi degrees of freedom flexible system point of interest to a pre-specified target position with zero residual vibration. The validity of the proposed controller is verified experimentally by controlling a sensorless dynamical system with finite degrees of freedom through measurements taken from its actuator.

This paper presents a novel sensorless force control algorithm for Multi-degree-of-freedom flexible systems which enables controlling the interaction forces with the environment without using force sensors. The coupled nature of flexible system dynamics makes it possible to estimate externally applied forces or torques that arise due to system's interaction with the environment. Disturbance and flexibility are simultaneously utilized to estimate system parameters, dynamics and externally applied forces or torques. The interaction torque estimate is then used to accomplish sensorless torque control assignment. This paper attempts to keep the flexible plant free from any measurement while performing a torque control assignment. However, actuator's parameters and variables are assumed to be available.

In bilateral control applications, time delays in the communication channel have destabilizing effects. In this paper, a new sliding mode observer based compensation technique is presented. Disturbance observer is utilized to make this sliding observer more robust to parameter changes. Simulation and experimental results show that the proposed method is successful in avoiding instability due to time delays and providing transparency between master and slave sides.

In this paper, a central controller for position/force hybrid control over network is proposed. In the proposed method, the central controller receives position and force information from each plant. Then, the central controller generates acceleration references for each plant by using a hybrid controller and a dead time compensator. As an application, bilateral control with communication delay is implemented. And some simulations and experiments verify the validity of the proposed method.

The problem of communication delay in bilateral or teleoperation systems is even more emphasized with the use of the internet for communication, which may give rise to loss of transparency and even instability. To address the problem, numerous methods have been proposed. This study is among the few recent studies taking a disturbance observer approach to the problem of time delay, and introduces a novel sliding-mode observer to overcome specifically the effects of communication delay in the feedback loop. The observer operates in combination with a PD+ controller which controls the system dynamics, while also compensating load torque uncertainties on the slave side. To this aim, an EKF based load estimation algorithm is performed on the slave side. The performance of this approach is tested with computer simulations for the teleoperation of a 1-DOF robotic arm. The simulations reveal an acceptable amount of accuracy and transparency between the estimated slave and actual slave position under both constant and random measurement delay and variable and step-type load variations on the slave side, motivating the use of the approach for internet-based bilateral control systems.

This paper presents a sensorless torque estimation algorithm for multidegree-of-freedom flexible systems. The proposed algorithm makes it possible to estimate externally applied torques due to flexible system's interaction with the environment without taking any measurement from the system. The algorithm is based on modifying the disturbance observer in order to decouple the reflected torque waves out of the total disturbance on the actuator. Then Reflected torque waves are used along with the actuator's current and velocity to estimate flexible system parameters, dynamics and the external torques or disturbances. Several experimental results are included in order to confirm the validity of the proposed torque estimation algorithm.

In this paper motion control systems with delay in measurement and control channels are discussed and a new structure of the observer-predictor is proposed. The feature of the proposed system is enforcement of the convergence in both the estimation and the prediction of the plant output in the presence of the variable, unknown delay in both measurement and in the control channels. The estimation is based on the available data - undelayed control input, the delayed measurement of position or velocity and the nominal parameters of the plant and it does not require apriori knowledge of the delay. The stability and convergence is proven and selection of observer and the controller parameters is discussed. Experimental results are shown to illustrate the theoretical predictions.

SURALP is a new walking humanoid robot platform designed at Sabanci University - Turkey. The kinematic arrangement of the robot consists of 29 independently driven axes, including legs, arms, waist and a neck. This paper presents the highlights of the design of this robot and experimental walking results. Mechanical design, actuation mechanisms, sensors, the control hardware and algorithms are introduced. The actuation is based on DC motors, belt and pulley systems and Harmonic Drive reduction gears. The sensory equipment consists of joint encoders, force/torque sensors, inertial measurement systems and cameras. The control hardware is based on a dSpace digital signal processor. A smooth walking trajectory is generated. A variety of controllers for landing impact reduction, body inclination and Zero Moment Point (ZMP) regulation, early landing trajectory modification, and foot-ground orientation compliance and independent joint position controllers are employed. A posture zeroing procedure is followed after manual zeroing of the robot joints. The experimental results indicate that the control algorithms presented are successful in improving the stability of the walk.

In 2D microassembly applications, it is inevitable to position and orient polygonal micro-objects lying on a flat surface. Point contact pushing of micro-objects provides a feasible way to achieve the task and it is more flexible and less complex compared to pick and place operation. Due to the fact that in micro-world surface forces are much more dominant than inertial forces, and tend to be unevenly distributed, these dominant forces obstruct the desired motion of the micro-object when using point contact pushing alone. Thus by adopting an hybrid vision/force feedback scheme, it is possible to attain a translation motion of the object as the uncertainties due to varying surface forces and disorientation of the micro-object is compensated by force and vision feedback respectively. In this paper, a hybrid vision/force feedback scheme is proposed to push micro-objects with human assistance using a custom built tele-micromanipulation setup to achieve translational motion. The pushing operation is divided into two concurrent processes: In one human operator acts as an impedance controller alters the velocity of the pusher while in contact with the micro-object through scaled bilateral teleoperation to compensate for varying surface forces. In the other process, the desired line of pushing for the micro-object is determined continuously using visual feedback procedures so that it always compensate for the disorientation. Experimental results are demonstrated to prove nano-Newton range force sensing, scaled bilateral teleoperation with force feedback and pushing micro-objects.

This paper presents an algorithm for parameters and positions estimation of lumped flexible systems. As soon as the parameters and the positions are estimated they can be used to design virtual sensors that can be moved along the system to estimate the position of any lumped mass keeping the system free from any attached sensors. The virtual sensors are nothing but a chain of estimators that are connected at the end of each other, starting with two actuator's measurements and ending up with system parameters and all the system lumped positions. An estimation Based PID controller is presented based on the feedback of the virtual sensor's estimates instead of the actual measurement.