Fast redundancy resolution for high-dimensional robots executing prioritized tasks under hard bounds in the joint space

Abstract

A kinematically redundant robot with limited motion capabilities, expressed by inequality constraints of the box type on joint variables and commands, needs to perform a set of tasks, expressed by linear equality constraints on robot commands, possibly organized with priorities. Robot motion capabilities cannot be exceeded at any time, and the resulting constraints are to be considered as hard bounds. Instead, robot tasks can be relaxed by velocity scaling if no feasible solution exists. To address this redundancy resolution problem, we developed a method in which joint space commands are successively saturated and their effect compensated in the null space of a suitable task Jacobian (SNS, Saturation in the Null Space). Computationally efficient versions of the basic and optimal SNS algorithms are proposed here, based on a task augmentation reformulation, a QR factorization of the main matrices involved, and a so-called warm start procedure. The obtained performance allows to control in real time robots with high-dimensional configuration spaces executing a large number of prioritized tasks, and with an associated high number of hard bounds that saturate during motion

Control of Redundant Robots Under Hard Joint Constraints: Saturation in the Null Space

“…In this paper, we present the Saturation in the Null Space (SNS) method, consolidating and expanding the results of our more recent works [23]- [26].…”

“…With respect to our conference papers [23]- [26], many new contributions have been included here. A common formalism has been used for all SNS versions, with a more intuitive presentation of the basic algorithm.…”

Cinemática inversa de un robot redundante tipo scorbot – ER Vplus: influencia de índices de desempeño

“…Dentro de las posibles soluciones a esta redundancia cinemática se encuentran los enfoques de descomposición de tareas [8]- [10], criterios de desempeño del manipulador para evitar singularidades y para evitar obstáculos [14], [15] y criterios basados en su dinámica [15], [16].…”

Iterative path-accurate trajectory generation for fast sensor-based motion of robot arms

“…In addition to the above task requirements, Refs. [9,[37][38][39] allow to optimize further degrees of freedom (dof). In this way, collisions of the robot arm may be inhibited while tracking the pose of the tool center point (tcp).…”