Modeling and Path-Following Control of a Wheelchair in Human-Shared Environments

Abstract

This work presents the kinematic and dynamic modeling of a human–wheelchair system which considers that its center of mass is not located in the middle of the wheel’s axle. Furthermore, a novel motion controller is presented for a human–wheelchair system, which is capable of performing positioning and path-following tasks in human-shared environments. This controller design is based on two cascaded subsystems: a kinematic controller, and a dynamic controller that compensates the dynamics of the human–wheelchair system. Additionally, an algorithm based on fuzzy-logic is proposed and incorporated in the aforementioned path-following control for pedestrian collision avoidance. This methodology considers to quantify heuristics social rules to make a balance between modulating velocity or direction during the avoidance. Three different interference cases, commonly found during walking events, are tested in a structured scenario. The experimental results demonstrate that the system is capable of overcoming many usual interference situations with human obstacles. A good performance of the path-following control is also verified.

Three-Dimensional Unified Motion Control of a Robotic Standing Wheelchair for Rehabilitation Purposes

“…Simple PD servo controllers are considered to control each joint. They are described by the following expressions, according to [17]. 6)- (20), we obtain the dynamic model of the wheelchair; the control signals to be considered are the reference velocities of the wheelchair robot:…”

“…Traditionally, the motion control design of a mobile robot with differential drive has considered, as a point of interest, the center of the virtual axis (located between the fixed wheels of the robot) [ 34 ]. In this work, we consider a point of interest displaced from the center of the virtual axis of the fixed wheels, so that the dynamic compensation of the robotic system delivers a real behavior, i.e., the standing wheelchair robot corrects errors generated by different external factors, such as the user’s change in posture or the friction of the different surfaces, among others [ 17 , 21 ]. Figure 1 illustrates the point of interest displaced a distance “a” from the standing wheelchair robot.…”

“…To achieve this, these controllers are taken into account and included in the modeling developed in this work. Assuming that the right and left motors have similar characteristics, the actuator models, without considering inductance voltages, according to [ 17 ], are expressed in the form …”

“…Multiple methods are used for therapy of people with injuries, providing a better lifestyle for daily tasks. Thus, depending on the type of disability that the patient presents, there are robotic mechanisms that facilitate safe movements, and even most mechanisms offer a certain degree of autonomy to the person by providing motor assistance, e.g., crutches, walkers, canes, exoskeletons, and mobile chairs, among other prototypes that allow people to move around [ 17 , 18 ].…”

“…The independence of the robotic system is obtained through the automatic generation of tracking control, which allows following the desired trajectory of the wheelchair. The motion control of the robotic system may have three types of problems: ( i) point stabilization control : stabilizes the wheelchair with standing considering one target point [ 17 ]; ( ii) trajectory tracking control : whose purpose is to allow the standing wheelchair to follow a parameterized reference in time [ 33 ]; and ( iii) path-following control: allows the robotic system to converge with desired trajectory [ 21 ].…”