Sensorless Optimal Interaction Control Exploiting Environment Stiffness Estimation

Roveda, Loris; Shahid, Asad Ali; Iannacci, Niccolò; Piga, Dario

doi:10.1109/tcst.2021.3061091

Cited by 29 publications

(17 citation statements)

References 39 publications

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“…Although the second is a realistic assumption, the first one limits possible applications. Online estimation of the environment shape has been investigated for rigid surfaces [32], [33] by employing force measurements, and for nonrigid surfaces [6] by estimating the environment stiffness in an indirect force control scheme. Computer vision-based solutions have also been explored for both rigid [34] and nonrigid [35] environments as well.…”

Section: Discussionmentioning

confidence: 99%

“…To the first category belong the impedance and admittance controllers [5]. These approaches are well suited for nonrigid environments, and they can achieve force control without the necessity of a force sensor, although the surface stiffness is still required to be known a priori, or it has to be estimated online as in [6]. To the second category belong the hybrid force/motion and the parallel position/force controllers.…”

Section: Introductionmentioning

confidence: 99%

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A Force/Motion Control Approach Based on Trajectory Planning for Industrial Robots With Closed Control Architecture

Gutiérrez–Giles

Evangelista-Hernandez

Arteaga

et al. 2021

IEEE Access

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Most industrial robots are provided by the manufacturer with a controller that cannot be modified by the user (e.g. a standard PID). This arrangement is commonly referred to as closed control architecture, since it is not possible to program arbitrary control laws. For the implementation of novel algorithms, it is on the contrary necessary to employ an open control architecture, which allows programming any control scheme. For that reason, it is customary to have testbeds that are made up of robot manipulators specially designed for this goal. Another disadvantage of the closed control architecture is that the controller provided by the manufacturer usually does not include a force control term since it allows only to program desired motion trajectories. To overcome these drawbacks without physically modifying the closed control architecture, this contribution presents a novel approach to simultaneously follow position and force trajectories by employing only motion planning, i.e. only by choosing the desired position trajectory. The approach is especially well suited for DC motor actuators with large gear reduction ratios as those of many industrial robots. The convergence of the manipulator position and applied force depends exclusively on the performance of the controller provided by the manufacturer. The approach is tested on a dual-arm cooperative manipulation system made up of two ABB IRB-2400 industrial robots with closed control architecture.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Force/Motion Control Approach Based on Trajectory Planning for Industrial Robots With Closed Control Architecture

Gutiérrez–Giles

Evangelista-Hernandez

Arteaga

et al. 2021

IEEE Access

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“…This means that, when interacting with a soft environment (i.e., 𝑛 𝑖 = 0), the controller is imposed to behave as the admittance controller; when interacting with a stiff environment (i.e., 𝑛 𝑖 = 1), the controller is imposed to behave as the impedance controller; and when interacting with a medium environment, the duty cycle 𝑛 𝑖 is adapted based on the defined relation in Equation (22), on the basis of the value of the interaction environment stiffness 𝐾 𝑒𝑛𝑣,𝑖 , and considering the stiffness range for the medium environment within the values 𝐾 𝑚𝑖𝑛 𝑒𝑛𝑣,𝑖 and 𝐾 𝑚𝑎𝑥 𝑒𝑛𝑣,𝑖 . The choice of such parameters converts the adaptation law described by Ott et al [13] and shown in Figure 10 into the one shown in Figure 11.…”

Section: Variable Duty 𝑛mentioning

confidence: 99%

“…Remark 1.The environment stiffness parameter 𝐾 𝑒𝑛𝑣,𝑖 estimation can be performed as described by the authors of [21,22] . Remark 2.The stability of the controller can be addressed following the work in [12,13] .…”

Section: Variable Duty 𝑛mentioning

confidence: 99%

Improved impedance/admittance switching controller for the interaction with a variable stiffness environment

Formenti¹,

Bucca²,

Shahid³

et al. 2022

Complex Eng Syst

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Hybrid impedance/admittance control aims to provide an adaptive behavior to the manipulator in order to interact with the surrounding environment. In fact, impedance control is suitable for stiff environments, while admittance control is suitable for soft environments/free motion. Hybrid impedance/admittance control, indeed, allows modulating the control actions to exploit the combination of such behaviors. While some work has addressed the proposed topic, there are still some open issues to be solved. In particular, the proposed contribution aims: (i) to satisfy the continuity of the interaction force in the switching from impedance to admittance control when a feedforward velocity term is present; and (ii) to adapt the switching parameters to improve the performance of the hybrid control framework to better exploit the properties of both impedance and admittance controllers. The proposed approach was compared in simulation with the standard hybrid impedance/admittance control in order to show the improved performance. A Franka EMIKA panda robot was used as a reference robotic platform to provide a realistic simulation.

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“…The adaptation of the Cartesian impedance control parameters has been also implemented in order to modulate the coupled robotenvironment interaction dynamics. Such a control approach has been extended in [35], proposing an optimized interaction controller exploiting the coupled robot-environment dynamics modeling.…”

Section: ) Sensorless Force Controlmentioning

confidence: 99%

Sensorless Optimal Switching Impact/Force Controller

et al. 2021

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Intelligent interaction control is required in many fields of application, in which different operative situations have to be faced with different controllers. Being able to switch between optimized controllers is, indeed, of extreme importance to maximize the task performance in the different operative conditions (i.e., free-space motion and contact), especially when considering sensorless robots. To deal with the proposed context, a sensorless optimal switching impact/force (OSIF) controller is proposed. The low-level robot control is composed of an inner joint position controller, fed by an outer Cartesian impedance controller with a reference position. The estimation of the external wrench is implemented by means of an Extended Kalman Filter (EKF). The high-level controller (feeding the Cartesian impedance controller with the setpoint) is composed of an optimized impact controller (LQR-based controller), an optimized force controller (SDREbased controller), and a continuous switching mechanism (Fuzzy Logic-based). In addition, the output of the switching mechanism is used to adapt the Cartesian impedance control parameters (i.e., stiffness and damping parameters). Experimental tests have been performed on a Franka EMIKA panda robot to validate the proposed controller. Obtained results show the capabilities of the OSIF controller, being able to detect task phase transitions while satisfying the target performance.

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Sensorless Optimal Interaction Control Exploiting Environment Stiffness Estimation

Cited by 29 publications

References 39 publications

A Force/Motion Control Approach Based on Trajectory Planning for Industrial Robots With Closed Control Architecture

A Force/Motion Control Approach Based on Trajectory Planning for Industrial Robots With Closed Control Architecture

Improved impedance/admittance switching controller for the interaction with a variable stiffness environment

Sensorless Optimal Switching Impact/Force Controller

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