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

Abstract

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.

Position-based visual servoing for pallet picking by an articulated-frame-steering hydraulic mobile machine

“…Alternative detection methods without the use of markers, for example, using active sensors, will also improve the reliability of the system. Further development of this work can be a visual servoing platform to utilize a path follower controller addressed in [25] for complex mobile robot architectures.…”

Path Following Controller for Differentially Driven Planar Robots with Limited Torques and Uncertain and Changing Dynamics

“…Their applications are widely spread across many industries such as service industry, agriculture, and defense. Although they somewhat lack in mobility when compared, for example, to pseudo-omnidirectional robots such as [1][2][3][4], differentially driven nonholonomic robots are in most cases more robust and affordable. In practice, most of these systems are provided with velocity control interfaces, such as the ROS differential drive controller interface [5] or those in the commercially available Pioneer and Khepera robots.…”

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

“…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. Such controller is shown to be successful in passing by singular configurations, while respecting the actuator velocity limits.…”

“…Acceleration limits were further taken into account in [8]. However, the methods developed in [11] and [8] result in the maximum steering/driving velocity for the axis passed by the ICR. While they can handle the scenario 1 mentioned above, they are not suitable for scenario 2.…”