L.M. Capisani

University of Pavia, Ticinum, Lombardy, Italy

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Publications (11)15.52 Total impact

  • L.M. Capisani, A. Ferrara
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    ABSTRACT: The problem of determining an interaction control strategy, allowing a manipulator to reach a goal point even in the presence of unknown obstacles, is faced in this paper. To this end, on the basis of position/orientation and force measurements, first, a path planning strategy is proposed. The path planning is based on an a priori trajectory, which is determined without the prior knowledge of the obstacle presence in the workspace, and on a real-time approach to generate auxiliary temporary trajectories on the basis of the properties of the obstacle surface in a vicinity of the contact point, estimated through force measurements. To determine the input laws of the manipulator, a robust hybrid position/force control scheme is adopted. First- and second-order sliding mode controllers are considered to generate the robot input laws, and the obtained performances are experimentally compared with those of classical PD control. Experiments are made on a COMAU SMART3-S2 anthropomorphic industrial manipulator.
    IEEE Transactions on Industrial Electronics 01/2012; 59(8):3189-3198. · 6.50 Impact Factor
  • A. Calanca, L.M. Capisani, A. Ferrara, L. Magnani
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    ABSTRACT: This paper proposes a practical multi-input multi-output (MIMO) closed loop parameters identification procedure for robot manipulators. It is based on the weighted least squares (WLS) method, coupled with particular solutions to facilitate the estimation, reducing the noise effect. More precisely, a two steps procedure to reduce the condition number of the input data matrix with optimal trajectory planning, and a method to estimate the variances matrix to be used as a weight matrix for the WLS method are illustrated. Moreover, the identification problem is solved with reference to an MIMO coupled system. A closed loop identification is needed because the system is open loop unstable, and because the robot has to track an optimal reference input so as to correctly execute the identification procedure. Some solutions are also presented to overtake common identification problems, such as the bias of the estimated parameters, the presence of outliers, the necessity of balancing the kinematics of the third link, and the reduction of the sensitivity to noise of the estimate. The presented procedure has been successfully experimentally tested on a COMAU SMART3-S2 industrial manipulator used in a planar configuration.
    IEEE Transactions on Control Systems Technology 10/2011; · 2.52 Impact Factor
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    ABSTRACT: This paper deals with the hybrid position/force control of a class of robotic manipulators. To perform the control scheme design, it is necessary to characterize the dynamical model of the force sensor which is mounted at the end-effector of the robot. The objective is to perform reliable contact force measurements by estimating all the forces which are generated at the level of the tip which is directly connected to the sensor. A dynamical model of the sensor motion is formulated and identified, by considering also the kinematics of the robot. The proposed hybrid control scheme includes position and force controllers based on first and second order sliding modes. These kind of controllers guarantee suitable robustness properties to perform a satisfactory trajectory tracking, also allowing one to make the robot move in an environment with unknown obstacles by using the possibility of touching the obstacles as a way to pass them by. Experimental tests are performed on a COMAU SMART3-S2 anthropomorphic rigid robot manipulator with an ATI Gamma force sensor by comparing four different position/force control schemes.
    Decision and Control, 2009 held jointly with the 2009 28th Chinese Control Conference. CDC/CCC 2009. Proceedings of the 48th IEEE Conference on; 01/2010
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    D. Brambilla, L.M. Capisani, A. Ferrara, P. Pisu
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    ABSTRACT: The problem of detecting actuator and sensor faults of a robot manipulator using a model-based Fault Detection (FD) technique is addressed. With the proposed FD scheme it is possible to detect a single fault, which can occur on a specific actuator or on a specific sensor. The proposed scheme is composed by an Unknown Input Observer (UIO) and a modified Generalized Observer Scheme (GOS) to make analytical redundancy. The first enables the actuators FD, while the second enables the FD on the sensors. The Sub-Optimal Second Order Sliding Mode Control (SOSMC) approach is exploited to determine the input laws of the observers. The proposed approach is verified in simulation and experimentally on a COMAU SMART3-S2 robot manipulator.
    Decision and Control, 2008. CDC 2008. 47th IEEE Conference on; 01/2009
  • D. Brambilla, L.M. Capisani, A. Ferrara, P. Pisu
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    ABSTRACT: This paper presents a model-based fault detection (FD) and isolation scheme for rigid manipulators. A single fault acting on a specific actuator or on a specific sensor of the manipulator is detected (and, if possible, the exact location of the fault), and an estimation of the fault signal is performed. Input-signal estimator and output observers are considered in order to make the FD procedure possible. By using the suboptimal second-order sliding-mode (SOSM) algorithm to design the input laws of the observers, satisfactory stability properties of the observation error are established. The proposed algorithm is verified in simulation and experimentally on a COMAU SMART3-S2 robot manipulator.
    IEEE Transactions on Industrial Electronics 12/2008; · 6.50 Impact Factor
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    ABSTRACT: Trajectory planning and tracking are crucial tasks in any application using robot manipulators. These tasks become particularly difficult when obstacles are present in the manipulatorpsilas workspace. In this paper it is assumed that the obstacles can be approximated in a conservative way with discs. The goal is to represent the obstacles in the robot configuration space, in order to allow an efficient and accurate trajectory planning and tracking. Moreover, the paper provides the methods for checking the collision between the n-joint manipulator and the obstacles. Trajectory planning depends on tracking accuracy. In this paper an adequate tracking accuracy is guaranteed assuming the use of a suitably designed robust controller.
    Emerging Technologies and Factory Automation, 2008. ETFA 2008. IEEE International Conference on; 10/2008
  • D. Brambilla, L.M. Capisani, A. Ferrara, P. Pisu
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    ABSTRACT: A simple model based fault detection (FD) scheme suitable for robot manipulators is presented. The purpose is to detect and, possibly, identify a single fault acting on a specific input or on a specific output of the manipulator. Input signal estimators and output observers are considered in order to make the fault detection possible. By adopting a second order sliding mode (SOSM) approach to design the input laws of the observers, it is possible to establish satisfactory stability properties of the observation error, and reduce the chattering effect. The proposed approach is experimentally tested on a COMAU SMART3-S2 manipulator.
    Variable Structure Systems, 2008. VSS '08. International Workshop on; 07/2008
  • L.M. Capisani, A. Ferrara, L. Magnani
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    ABSTRACT: This paper presents a control strategy for robot manipulators, based on the coupling of the inverse dynamics method with the so-called second order sliding mode control approach. The motivation for using sliding mode control in robotics mainly relies on its appreciable features, such as design simplicity and robustness. Yet, the chattering effect, typical of the conventional sliding mode control, can be destructive. In this paper, this problem is suitably circumvented by adopting a second order sliding mode control approach characterized by a continuous control law. To design the inverse dynamics part of the proposed controller, a suitable dynamical model of the system has been formulated, and its parameters have been accurately identified. The proposed inverse dynamics-based second order sliding mode controller has been experimentally tested on a COMAU SMART3-S2 industrial manipulator, demonstrating the tracking properties and the good performances of the controlled system.
    Decision and Control, 2007 46th IEEE Conference on; 01/2008
  • L.M. Capisani, A. Ferrara, L. Magnani
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    ABSTRACT: This paper proposes a practical parameters identification procedure for robot manipulators. It is based on the well-known maximum likelihood method adopting particular techniques to facilitate the estimation: condition number reduction methods for the input data matrix with optimal trajectory planning, and two different methods for variances estimation. Moreover, the identification problem is solved with reference to the multi input multi output coupled system. A closed loop identification is needed because the system is open loop unstable, and, moreover, because to correctly execute the identification procedure, the robot has to track an optimal reference input. Some solutions are also presented to overtake common identification problems, such as bias of the estimated parameters, outliers detection and elimination, and noise sensitivity of the estimation. The presented procedure was successfully tested on a COMAU SMART3-S2 industrial manipulator demonstrating its efficiency.
    Advanced intelligent mechatronics, 2007 IEEE/ASME international conference on; 10/2007
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    ABSTRACT: The problem of estimating the thermal state of an induction cooking system is analyzed. The first step is to model the thermal system composed by the cooktop, the pot, and the pot content. Then, by relying on the formulated model, the aim is to design a suitable state observer, so that an estimation of the temperature of the cooking vessel content can be made online. Two kinds of observers are proposed. An Extended Kalman Filter (EKF) and a Sliding Mode Observer (SMO). A comparison of the performances which can be obtained with these two solutions is then made by relying on experimental results obtained on a real induction cooktop heating a pot containing a certain quantity of water.
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    ABSTRACT: In this work, the joint position tracking control problem of industrial robots is tackled. To cope with the model uncertainties and external disturbances affecting the robot, the Inverse Dynamic Controller (IDC) is combined with an approach based on higher order Sliding Mode Control (SMC) technique. We make use, in particular, of the so-called "Twisting" Second Order Sliding Mode Controller. Higher order SMC techniques transfer the inherent discontinuities to the time derivative of the input torque and this allows to obtain a continuous profile for the input torque, which is computed through integration of an appropriate discontinuous switching signal. Despite the chattering phenomenon is strongly attenuated, some residual problems (vibration and acustical noise) are still observed during the experimental implementation of such an approach in its standard formulation. To improve the system performance we suggest in this work an adaptation mechanism to adjust on-line the authority of the SMC. The logic is driven by a "sliding-mode indicator" that detects, on line, the occurrence of a sliding mode behaviour and uses this information for adaptation purposes. When large and fast control activity is demanded (e.g. to track fast reference trajectories) the adaptation unit reacts by automatically increasing the control authority of the SMC. On the other hand when small control authority is sufficient the control magnitude is lowered. Such a bidirectional adaptation logic significantly reduces the chattering. The proposed technique is theoretically analyzed and experimentally tested, and the results of comparative experiments are discussed in the paper.