Passivity-based control for haptic teleoperation of a legged manipulator in presence of time-delays

Abstract

When dealing with the haptic teleoperation of multi-limbed mobile manipulators, the problem of mitigating the destabilizing effects arising from the communication link between the haptic device and the remote robot has not been properly addressed. In this work, we propose a passive control architecture to haptically teleoperate a legged mobile manipulator, while remaining stable in the presence of time delays and frequency mismatches in the master and slave controllers. At the master side, a discrete-time energy modulation of the control input is proposed. At the slave side, passivity constraints are included in an optimization-based whole-body controller to satisfy the energy limitations. A hybrid teleoperation scheme allows the human operator to remotely operate the robot's endeffector while in stance mode, and its base velocity in locomotion mode. The resulting control architecture is demonstrated on a quadrupedal robot with an artificial delay added to the network.

Teleoperation of Humanoid Robots: A Survey

“…Then, a system is passive if the energy of the output waves is less than the energy of input waves. In a recent work by [124] on bilateral teleoperation of legged robot mobile manipulators, to ensure the passivity and stability they used energy tanks as energy observers and included that as a constraint to the robot whole-body control layer. The problem is that achieving passivity does not guarantee good performance [122], and stability and transparency are conflicting objectives [18].…”

High Utility Teleoperation Framework for Legged Manipulators Through Leveraging Whole-Body Control

“…In the effort of overcoming these limitations, motion capture suits are becoming more popular in research, where they are seen to control humanoid robots [18], quadrupeds [19], wheeled manipulators [20] and manipulators [21]. As such they have been seen to be utilised in research when coupled with a WBC to improve efficiency, through utilising redundancy, and stability.…”

“…Consequently, these frameworks are sub-optimal for completing jobs in hazardous environments, as quadrupedal manipulators offer a naturally more kinematically stable system. This has been resolved in [19] and [27] where a teleoperation-WBC frameworks for quadrupedal manipulators are presented. However, in [19] only the manipulator end-effector and gait commands can be sent to the robot and only end-effector and trunk commands can be sent in [27], which would prove insufficient when dealing with tasks that involve manipulation using more than one end-effector.…”