Kinesthetic Guidance Utilizing DMP Synchronization and Assistive Virtual Fixtures for Progressive Automation

Abstract

SUMMARYThe progressive automation framework allows the seamless transition of a robot from kinesthetic guidance to autonomous operation mode during programming by demonstration of discrete motion tasks. This is achieved by the synergetic action of dynamic movement primitives (DMPs), virtual fixtures, and variable impedance control. The proposed DMPs encode the demonstrated trajectory and synchronize with the current demonstration from the user so that the reference generated motion follows the human’s demonstration. The proposed virtual fixtures assist the user in repeating the learned kinematic behavior but allow penetration so that the user can make modifications to the learned trajectory if needed. The tracking error in combination with the interaction forces and torques is used by a variable stiffness strategy to adjust the progressive automation level and transition the leading role between the human and the robot. An energy tank approach is utilized to apply the designed controller and to prove the passivity of the overall control method. An experimental evaluation of the proposed framework is presented for a pick and place task and results show that the transition to autonomous mode is achieved in few demonstrations.

A passive admittance controller to enforce Remote Center of Motion and Tool Spatial constraints with application in hands-on surgical procedures

“…Active constraints or virtual fixtures were firstly introduced in tele-robotic manipulation by Rosenberg providing force feedback from virtual environments to reduce the cognitive load of the user [27,28] and have been utilized for both hands-on and teleportation applications in surgical [4-6, 9, 12, 29, 30] industrial [2,7,8,31,32] or even in underwater robotic tasks [11]. They can be classified as either virtual fixtures for enforcing barriers around forbidden regions [1,[9][10][11][12]30] or virtual fixtures for assisting guidance achieving an attractive behavior towards a desired path [2,[4][5][6][7][8]29]. Notice that an attractive virtual fixture in a region can be assumed as a forbidden-region virtual fixture for its complementary space and vice versa.…”

“…In surgery spatial constraints are related to forbidden regions. These constraints can be known analytically [1][2][3][4][5][6], can be generated utilizing Dynamic Movement Primitives that encode the demonstration trajectory [7,8] or provided as point clouds produced by the perception system [9][10][11][12]. RCM enforcement schemes are mainly proposed for robotic assisted minimal invasive surgery (RAMIS) [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26].…”

A control scheme for haptic inspection and partial modification of kinematic behaviors

“…In this way, we can guarantee the passivity of the system, which is one of our objectives. Notice that the energy provided by the energy tank is utilized for the advancement of the evolution of the DS, which is different to the common methods involving energy tanks for interaction with dynamical systems [16], [28], [29]. The latter utilize the stored energy to adjust the impedance.…”

Special Issue on Human–Robot Interaction (HRI)

“…Their approach is based on admittance control, applied to any position-controlled robot with mounted force/torque sensor at the end-effector and the developed system has been validated by experiments. Virtual fixtures, variable impedance control, and dynamic movement primitives are used synergistically to program a robot by demonstration in order to execute autonomously discrete motion tasks (Papageorgiou et al 6 ). The primitives encode the demonstrated trajectory and synchronize with the current demonstration from the user so that the generated reference motion follows the human's demonstration.…”