This paper discusses parallel wire mechanisms where an end-effector of the mechanism is suspended by multiple wires. The mechanisms enable not only three-dimensional (3-D) positioning but also 3-D orienting of the end-effector, unlike typical wire suspension-type mechanisms such as overhead crane. To discuss the parallel-wire-suspended mechanisms generally, two forms of basic dynamic equations are presented. Then the parallel wire mechanisms are classified into two types based on the basic equations. Dynamical properties of the two types of wire-suspended positioning mechanism are discussed. In this paper, one of the wire-suspended mechanism, incompletely restrained-type parallel wire mechanism, is mainly discussed on its inverse dynamics problem and its trajectory control problem. The inverse dynamics problem for the incompletely restrained-type mechanism plays an important role on its control problem, because the mechanism has low stiffness based on incomplete constraints on the suspended object which is governed by its dynamics. The paper proposes an antisway control method for the suspended object. In the method, the inverse dynamics calculation is used for nonlinear dynamics compensation to control the suspended object of the incompletely restrained parallel wire mechanism.

Proposes a feedback control method for wire-suspended mechanisms. The wire-suspended mechanisms are classified into two types, which are completely restrained type mechanisms and incompletely restrained type mechanisms. The paper discusses mainly incompletely restrained type mechanisms form the viewpoint of actual control. The incompletely restrained type wire-suspended mechanism has the merit that it enables three dimensional positioning and orientation of suspended object with simple mechanism using a small number of wires. However it also has the drawback that the manipulated object is easy to swing as seen in overhead crane which is a simple incompletely restrained type mechanism. For this reason, an anti-sway control method for incompletely restrained type mechanisms is needed. To resolve the problem of swing, inverse dynamics for general incompletely restrained type wire-suspended mechanism is discussed, then a feedback control method based on dynamics compensation is presented.

This paper discusses a feedback control method for incompletely restrained wire-suspended mechanisms. The incompletely restrained wire-suspended mechanism has a merit that it enables three dimensional positioning and orientating of suspended object with simple mechanism using a small number of wires. However it also has a drawback that the manipulated object is easy to swing as seen in overhead crane which is one of the simplest incompletely restrained mechanism. For this reason, anti-sway control method for incompletely restrained type mechanisms is needed. A key point of our method is exact linearization using inverse dynamics of the system. Feedback control method with exact linearization and measuring method for the suspended object are presented, and effectiveness of proposed methods are shown by an experiment.

Discusses an inverse dynamics problem and proposes a trajectory generation method for wire-suspended mechanisms. The wire-suspended mechanisms are classified into two types, which are completely restrained type mechanisms and incomplete by restrained type mechanisms. For the incompletely restrained type mechanisms, consideration of dynamics is important, because the motion of this mechanism is governed by its dynamics and kinematics, whereas the motion of the completely restrained type mechanism is determined by only its kinematics. The paper discusses mainly the incompletely restrained type mechanisms from the viewpoint of dynamical properties. The incompletely restrained type wire-suspended mechanism has a merit that it enables three dimensional positioning and orientating of suspended object with simple mechanism using a small number of wires. However it also has a drawback that the manipulated object is easy to swing as seen in overhead crane which as a simple incompletely restrained type mechanism. To overcome the problem, inverse dynamics for general incompletely restrained type wire-suspended mechanism is discussed, then a condition on desired trajectory of manipulated object is presented on the basis of the inverse dynamics analysis. Using the desired trajectory, an online trajectory modification method for the control of manually operated overhead crane is proposed.

Proposes a control method for a crane using inverse dynamics calculation of the system. The load of a crane is generally easy to swing and thus the work using the crane is dangerous. For preventing the unfavorable swing of the load, it is desirable to feedback the actual position of the load in a control method. As such a control law, state-feedback control based on linearization of the crane system is often used. However the method reduces control performance when rope length is changed, because of nonlinearity of the system. In the paper, a feedback control method is proposed where the inverse dynamics calculation is involved to compensate non-linear dynamics of the system. In the control system, an observer is used to get higher order derivatives of the position of load, which is needed for the inverse dynamics calculation. By using the control method, control performance is unchangeable for changing rope length. Numerical simulation and experiment are shown to verify the effectiveness of the proposed control method.

This paper discusses an inverse dynamics problem for a parallel wire mechanism with multi-degrees of freedom. Firstly, a crane-type parallel wires mechanism which has three trolleys and three wires is proposed for handling heavy objects. This handling mechanism enables not only three dimensional positioning but also orientating of objects, unlike typical crane mechanism. A dynamical model using wire force vector is derived. Based on the dynamical model with wire force vector, inverse dynamics problem is analytically solved by a linear equation in terms of the wire force vector. The trajectory of end-effector of the crane-type manipulator can be transformed into the trajectory of wire length and trolley position by the calculation method. Using the trajectory of wire length and trolley position, the end-effector of the crane-type manipulator is controlled. Two dimensional experimental crane-type manipulator is also developed to verify an effectiveness of the inverse dynamics calculation and the trajectory control method.