Hybrid impedance and admittance control for optimal robot–environment interaction

Abstract

Compliant interaction between robots and the environment is crucial for completing contact-rich tasks. However, obtaining and implementing optimal interaction behavior in complex unknown environments remains a challenge. This article develops a hybrid impedance and admittance control (HIAC) scheme for robots subjected to the second-order unknown environment. To obtain the second-order target impedance model that represents the optimal interaction behavior without the accurate environment dynamics and acceleration feedback, an impedance adaptation method with virtual inertia is proposed. Since impedance control and admittance control have complementary structures and result in unsatisfactory performance in a wide range of environmental stiffness due to their fixed causality, a hybrid system framework suitable for the second-order environment is proposed to generate a series of intermediate controllers which interpolate between the responses of impedance and admittance controls by using a switching controller and adjusting its switching duty cycle. In addition, the optimal intermediate controller is selected using a mapping of the optimal duty cycle to provide the optimal implementation performance for the target impedance model. The proposed HIAC scheme can achieve the desired interaction and impedance implementation performance while ensuring system stability. Simulation and experimental studies are performed to verify the effectiveness of our scheme with a 2-DOF manipulator and a 7-DOF Franka EMIKA panda robot, respectively.

Design of a Wheelchair-Mounted Robotic Arm for Feeding Assistance of Upper-Limb Impaired Patients

“…Further investigations will be carried out in the future, aligning with previous simulation research efforts as reported in [28]. Additionally, future work will delve into control aspects, exploring impedance and admittance control for optimal robot-environment interaction, as proposed in works such as [29]. Attention will also be directed towards active learning of collision distance functionality, as suggested in [30] and [31].Furthermore, we aim to explore different end-effectors, such as grippers capable of manipulating not only food but also a wide range of objects, as proposed by Fu et al [32], Dong and Zhang [33], Carbone et al [34], and Yao et al [35].…”

“…Further investigations will be carried out in the future, aligning with previous simulation research efforts as reported in [28]. Additionally, future work will delve into control aspects, exploring impedance and admittance control for optimal robot-environment interaction, as proposed in works such as [29]. Attention will also be directed towards active learning of collision distance functionality, as suggested in [30,31].…”

Hybrid Adaptive Impedance and Admittance Control Based on the Sensorless Estimation of Interaction Joint Torque for Exoskeletons: A Case Study of an Upper Limb Rehabilitation Robot

“…Another study [18] proposed a hybrid impedance control where the controller concurrently achieves position motion tracking for rehabilitation and produces a force using an optimization process based on a musculoskeletal model. Recently, a hybrid impedance control mechanism for optimal environmental-robot interaction was presented in [19,20], which proposed an improved hybrid impedance control for variable stiffness environment interaction. Other parallel structured hybrid impedance control methods have been proposed elsewhere [21][22][23][24][25][26][27][28].…”

Development of a Multi-Robot System for Pier Construction

“…Admittance control is extensively researched and applied in contact-intensive applications such as automated assembly using robots and human-robot collaboration [18][19][20]. However, advanced admittance control systems that require modifications to joint control are impractical for application in commercial industrial robots due to their complexity.…”