Singularity-free state-space representation for non-holonomic, omnidirectional undercarriages by means of coordinate switching

Connette, Christian; Hägele, Martin; Verl, Alexander

doi:10.1109/iros.2012.6386131

Cited by 12 publications

(22 citation statements)

References 17 publications

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“…In this case, the ICR is theoretically located at infinity. In order to solve the representational singularity, coordinate switching is one of the proposed methods [9] [10]. The latter refers to the situation where the ICR is located along the steering axes.…”

Section: Introductionmentioning

confidence: 99%

Path Tracking Control of Self-Reconfigurable Robot hTetro With Four Differential Drive Units

Shi

Elara

et al. 2020

IEEE Robot. Autom. Lett.

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The research interest in mobile robots with independent steering wheels has been increasing over recent years due to their high mobility and better payload capacity over the systems using omnidirectional wheels. However, with more controllable degrees of freedom, almost all of the platforms include redundancy, which are modeled using the instantaneous center of rotation (ICR). This paper deals with a Tetris-inspired floor cleaning robot hTetro which consists of four interconnected differential-drive units. Each module has a differential drive unit which can steer individually. Differing from most other steerable wheeled mobile robots, the wheel arrangement of this robot changes because of its self-reconfigurability. In this paper, we proposed a path tracking controller that can handle discontinuous trajectories and sudden orientation changes for hTetro. Singularity problems are resolved on both the mechanical aspect and the control aspect. The controller is tested experimentally with the self-reconfigurable robotic platform hTetro, and results are discussed.

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Section: Introductionmentioning

confidence: 99%

Path Tracking Control of Self-Reconfigurable Robot hTetro With Four Differential Drive Units

Shi

Elara

et al. 2020

IEEE Robot. Autom. Lett.

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“…In [10], a complex formulation provides a locally singular-free representation, by switching between several state space representations of the twist. In [11], a time optimal controller is developed to account for the joint velocity limits.…”

Section: Introductionmentioning

confidence: 99%

“…While they can handle the scenario 1 mentioned above, they are not suitable for scenario 2. The simulations in [10] do not provide information on joint axes rates in the vicinity and at the singular configurations.…”

Section: Introductionmentioning

confidence: 99%

Kinematic modeling and singularity treatment of steerable wheeled mobile robots with joint acceleration limits

Sorour¹,

Cherubini²,

Fraisse³

2016

2016 IEEE International Conference on Robotics and Automation (ICRA)

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Non-holonomic omnidirectional mobile robots have higher load carrying capacity than their holonomic counterparts. Once the steer joint configuration is initialized, they can perform arbitrarily complex three-dimensional trajectories in the plane of motion and, as such, are more suitable for industrial contexts. However, their kinematic model presents representational and structural singularities, solutions to which must respect actuator performance limits. Recent research efforts have provided either simple restricting of the velocity space (among which few considered hardware limits) or complex non-restricting (no hardware limits considered) solutions. Most of these efforts are providing solutions at the kinematic control level. Instead, here we propose both a representational singularity free kinematic model, and a simple numeric treatment for the kinematic singularity. We further provide a method to tune the latter, to respect the actuator acceleration limits. Thanks to its steer rate damping behavior, the method can be further extended, to respect joint limits. Another benefit is the treatment of the singularity at the level of the kinematic model, which enhances real time capabilities. The developed method has been tested successfully on the Neobotix-MPO700 mobile robot and shown superior results as compared to the embedded controller.

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“…Authors in [16] proposed an alternative ICR representation to avoid such singularities. Results in [16] are later extended in [17], where a singular-free switching state space has been proposed that addresses both inherent and presentation singularities. In another approach by [18], to avoid singularity, each wheel has been given an extra degree of freedom which makes the wheels footprint variable.…”

Section: Introductionmentioning

confidence: 99%

A novel time optimal path following controller with bounded velocities for mobile robots with independently steerable wheels

Oftadeh

Ghabcheloo

Mattila

2013

2013 IEEE/RSJ International Conference on Intelligent Robots and Systems

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Mobile robots with independently steerable wheels possess many high maneuverability features of omnidirectional robots while benefiting from better performance and capability of moving on rough terrains. However, motion control of such robots is a challenging task due to presence of singular configurations and unboundedly large steering velocities in the neighborhood of those singularities. Many proposed approaches rely on numerical solutions that keep the robot out of bulky regions around the singular points and hence lose some of the robot maneuverability. Based on a class of traditional path followers we design a new globally stable path following controller that exploits the high maneuverability of the platform. This design allows us to derive a set of closedform analytical functions that describe the robot base velocity as a function of the wheels driving and steering velocities while abide to the robot non-holonomic constraints. Those functions are then utilized to find the maximum instantaneous velocity of the body that keeps the wheels velocities under the prespecified bounds no matter how much the robot gets close or far from its singular configurations. The control algorithms developed in this paper have been evaluated on iMoro, a four wheel independently steered mobile manipulator designed and developed at IHA/TUT. Experimental data is also shown that show efficacy of the method.

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Singularity-free state-space representation for non-holonomic, omnidirectional undercarriages by means of coordinate switching

Cited by 12 publications

References 17 publications

Path Tracking Control of Self-Reconfigurable Robot hTetro With Four Differential Drive Units

Path Tracking Control of Self-Reconfigurable Robot hTetro With Four Differential Drive Units

Kinematic modeling and singularity treatment of steerable wheeled mobile robots with joint acceleration limits

A novel time optimal path following controller with bounded velocities for mobile robots with independently steerable wheels

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