Formation-Based Control Scheme for Cooperative Transportation by Multiple Mobile Robots

Abstract

This paper presents a motion-planning and control scheme for a cooperative transportation system comprising a single rigid object and multiple autonomous non-holonomic mobile robots. A leader-follower formation control strategy is used for the transportation system in which the object is assumed to be the virtual leader; the robots carrying the object are considered to be followers. A smooth trajectory between the current and desired locations of the object is generated considering the constraints of the virtual leader. In the leader-follower approach, the origin of the coordinate system attached to the centre of gravity of the object, which is known as the virtual leader, moves along the generated trajectory while the real robots, which are known as followers, maintain a desired distance and orientation in relation to the leader. An asymptotically stable tracking controller is used for trajectory tracking. The proposed approach is verified by simulations and real applications using Pioneer P3-DX mobile robots.

Steering-angle computation for the multibody modelling of differential-driving mobile robots with a caster

“…Pioneer P3-DX is a popular commercial mobile robot with a differential-driving architecture, which has been widely used by the research community. 6,11,13,17,20 In robots with this architecture, two independently driving wheels are mounted on the rear shaft coaxially, while a caster wheel is articulated freely onto the platform of the mobile robot on the front of its centre line. In order to facilitate the motion analysis and the multibody modelling, the sketch of the DDMR framework with its links and connecting joints is included in Figure 1, based on the design principles of the kinematic chain for an actual robot.…”

“…Due to their simple and reliable propulsion mechanism, DDMRs are adopted in almost all research fields: pathtracking, [5][6][7][8][9] trajectory-planning, [10][11][12][13][14] position-estimation, 15,16 navigation control [17][18][19] and multi-robot control. [20][21][22] Robot models are the indispensable basis for the various applications mentioned earlier. Generally speaking, kinematics models are more popular in applications, not only for estimation 15,16 and planning, 11,13,14 but also for control.…”

“…Generally speaking, kinematics models are more popular in applications, not only for estimation 15,16 and planning, 11,13,14 but also for control. 8,17,18,20 Most kinematics models involve differential equations due to the nonholonomic constraints of DDMRs, 7,14,15,19,22 while some kinematics models are based on geometric relations that rely on the instantaneous centre of curvature or trajectory approximation at each sampling instant. [16][17][18]20 Besides the robot kinematics, it is important to consider the robot dynamics when highspeed movement and/or heavy-load operations are required in realistic work fields.…”

“…8,17,18,20 Most kinematics models involve differential equations due to the nonholonomic constraints of DDMRs, 7,14,15,19,22 while some kinematics models are based on geometric relations that rely on the instantaneous centre of curvature or trajectory approximation at each sampling instant. [16][17][18]20 Besides the robot kinematics, it is important to consider the robot dynamics when highspeed movement and/or heavy-load operations are required in realistic work fields. 23 The dynamics models can associate platform twist with motor armature voltage, 5 or with duty ratio of pulse width modulation of motor voltage, 12 or relate wheel forces to robot acceleration.…”

Development of a Simulation Platform for Underwater Transportation using Two Hovering Autonomous Underwater Vehicles

“…In the formation keeping approach, the vehicles maintain a formation relative to the payload while transporting it towards the target location. The formation is maintained by means of communication between the vehicles and the payload [3].…”