Front Casters Research Articles

Modelling and control of the motion of a trolley: Effect of motor dynamics on the dynamical model

This work deals with the modelling and control of the motion of a trolley. The trolley is composed from two rear wheels, each of them controlled separately by a DC-motor, and from a front castor wheel (see Figure 1). In order to obtain a set of dynamic equations of the trolley motion that include the motor dynamics, the trolley dynamics and the motor dynamics are coupled to obtain a set of third-order differential equations. Then two inverse dynamics transformations are applied successively, to enable one to use linear control for the design of guidance laws for steering the trolley.

Modeling and Control of a Hybrid Locomotion System

This paper describes a hybrid mobility system that combines the advantages of both legged and wheeled locomotion. The legs of the hybrid mobility system permit it to surmount obstacles and navigate difficult terrain, while the wheels allow efficient locomotion on prepared surfaces and provide a reliable passive mechanism for supporting the weight of the vehicle. We address the modeling, analysis and control of such hybrid mobility systems using the specific example of a wheelchair with two powered rear wheels, two passive front casters, and two articulated, two-degree-of-freedom legs. We exploit the redundancy in actuation to actively control and optimize the contact forces at the feet and the wheels. Our scheme for active traction optimization redistributes the contact forces so as to minimize the largest normalized ratio of tangential to normal forces among all the contacts. Simulation and experimental results for the prototype are presented to demonstrate and evaluate the approach.

Navigation and control of a system composed of a trolley and a mounted two-link manipulator

This work deals with the guidance and control of the motion of a system which is composed of a trolley and a mounted two-link manipulator. The trolley is composed from two rear wheels, each of them controlled separately, and from two front castor wheels (see Figure 1). Denote by ( x, y) the trolley's center of mass, and by α 1 and α 2 the angles with respect to the horizon of the manipulator arms. Given N points P i , i = 1, …, N in the horizontal plane, 2 N angles α kj , k = 1, 2, j = 1, …, N, a finite time interval [0, t f ], and a sequence of times τ 1 = 0 < τ 2 < … < τ N = t f . Based on a dynamical model of the system, and by using the concept of path controllability, a control law for the trolley's rear wheels and for the two-link manipulator torques is derived, to steer the system such that [( x, y), α 1, α 2] will pass through [ P j , α 1 j , α 2 j ] at the time τ j , j = 1, …, N, respectively.

Navigation and control of a trolley by using a dynamical model

This work deals with the guidance and control of the motion of a trolley. The trolley is composed from two rear wheels, each of them controlled separately, and from two front castor wheels (see Figure 1). Given N points P i , i = 1, …, N in the horizontal plane, a finite time interval [0, t f ], and a sequence of times τ 1 = 0 < τ 2 < ⋯ < τ N = t ƒ . Based on a dynamical model of the trolley, and by using the concept of path controllability, a control law for the trolley's rear wheels is derived, to steer the trolley's center ( x, y) in such a manner that ( x, y) will pass through P i at the time τ i , i = 1, …, N, respectively.