Trajectory tracking with a 6R serial industrial robot with ordinary and non-ordinary singularities

Gracia, Luis; Andrés, Javier; Tornero, Josep

doi:10.1007/s12555-009-0111-1

Cited by 17 publications

(16 citation statements)

References 18 publications

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“…Otherwise, the robot configuration q is said to be singular and the desired workspace velocity vectorṗ d in general cannot be achieved. That is, the square error of equation (4) given byq d in (6) is non-zero unlessṗ d = Uξ, i.e.ṗ d lies in the column space of J, which represents a non-ordinary singularity [18].…”

Section: Algebraic Problem Of Redundancymentioning

confidence: 99%

“…Consequently, the sliding regime generated by switching law (18) produces such equivalent control without explicit knowledge of it, with a reasonably low computational cost; this is a distinctive advantage of sliding-mode strategies.…”

Section: Multiple Active Constraintsmentioning

confidence: 99%

“…We are interested in exploiting the exact approximation to the constraint boundary that allow variable structure laws such as (18) to deal with the control problem stated in Section 2. In particular, we will employ the ideas of Section 3 to perform an on-line robotic redundancy resolution so that C-space limits given by equation (11) redundancy resolution is to instantaneously modify the desired joint velocity vectorq d which is sent to the joint controllers of the robot when there is a risk of violating a given constraint.…”

Section: Redundancy Resolution Schemementioning

confidence: 99%

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A supervisory loop approach to fulfill workspace constraints in redundant robots

Gracia

Sala

Garelli

2012

Robotics and Autonomous Systems

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ElsevierGracia Calandin, LI.; Sala, A.; Garelli, F. (2012). A supervisory loop approach to fulfill workspace constraints in redundant robots. Robotics and Autonomous Systems. 60 (1) AbstractAn approach based on geometric invariance and sliding mode ideas is proposed for redundancy resolution in robotic systems to fulfill configuration and workspace constraints caused by robot mechanical limits, collision avoidance, industrial security, etc. Some interesting features of the proposal are that: (1) it can be interpreted as a limit case of the classical potential fieldbased approach for collision avoidance which requires using variable structure control concepts, (2) it allows reaching the limit surface of the constraints smoothly, depending on a free design parameter, and (3) it can be easily added as a supervisory block to pre-existing redundancy resolution schemes. The algorithm is evaluated in simulation on a 6R planar robot and on the freely accessible 6R robot model PUMA-560, for which the main features of the method are illustrated.

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Section: Algebraic Problem Of Redundancymentioning

confidence: 99%

Section: Multiple Active Constraintsmentioning

confidence: 99%

Section: Redundancy Resolution Schemementioning

confidence: 99%

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A supervisory loop approach to fulfill workspace constraints in redundant robots

Gracia

Sala

Garelli

2012

Robotics and Autonomous Systems

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“…In that case, it is said that the variable structure control given by (13) presents strong invariance to disturbance d [4].…”

Section: Strong Invariancementioning

confidence: 99%

“…The method can also be applied, for instance, to avoid configurations where the robot kinematics is close to being singular, e.g. elbow, shoulder and wrist singularities [13].…”

Section: Configuration Space Constraintsmentioning

confidence: 99%

A path conditioning method with trap avoidance

Gracia

Sala

Garelli

2012

Robotics and Autonomous Systems

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This work presents a sliding-mode method for robotic path conditioning. The proposal includes a trap avoidance algorithm in order to escape from trap situations, which are analogous to local minima in potential field-based approaches. The sliding-mode algorithm activates when the desired path is about to violate the robot workspace constraints, modifying it as much as necessary in order to fulfill all the constraints and reaching their limit surface at low speed. The proposed path conditioning algorithm can be used on-line, since it does not require a priori knowledge of the desired path, and improves the conventional conservative potential field-based approach in the sense that it fully exploits the robot workspace. The proposed approach can be easily added as an auxiliary supervisory loop to conventional robotic planning algorithms and its implementation is very easy in a few program lines of a microprocessor. The proposed path conditioning is compared through simulation with the conventional potential field-based approach in order to show the benefits of the method. Moreover, the effectiveness of the proposed trap avoidance algorithm is evaluated by simulation for various trap situations.

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