Xingguo Shao

Non-smooth dynamical analysis and experimental validation of the cable-suspended parallel manipulator

The cable-suspended parallel manipulator replaces the rigid links of traditional parallel robot. The unilateral property of the cable complicates the dynamic analysis of such manipulator and further induces difficulty in control problem. The set-valued tension law is proposed to model the unilateral constraint of the cable, and the dynamics of cable-suspended parallel manipulator is analyzed in the framework of non-smooth dynamics. The resulting non-smooth dynamics model consists of a set of differential–algebraic equations with inequality constraints. Its solution is found by the Moreau midpoint method. An experimental setup was established to verify and validate the effectiveness and accuracy of non-smooth dynamics. And the simulation results generally agree with the experimental results, which demonstrate that the non-smooth dynamics is effective and reasonable for the dynamic analysis of the cable-suspended parallel manipulator. The results of this article deeply reveal the dynamics of the cable-suspended parallel manipulator, and may be used to design more accurate controller for its trajectory control.

Forward kinematics analysis and experimental validation of a four-cable-driven under-constrained parallel mechanism

Taking the sinking winch mechanism as prototype, this paper studies the forward kinematics problem of a four-cable-driven under-constrained parallel mechanism. The tension states (slackness and tautness) and properties of the cables are incorporated into the forward kinematics model. We propose a new algorithm (named traversal algorithm) to solve the tensions in cables and the pose of platform, under the condition that only the lengths of four cables are known. The simulation and experimental results on forward kinematics demonstrate the effectiveness and correctness of the model and the traversal algorithm. The results of this paper can be used to evaluate the effect of the unequal cables’ lengths to the tension distribution of cables and pose of the platform for sinking winch mechanism.

Coupled Extensional-Torsional Vibration Frequency of Hoisting Rope in Tower-Type Friction Drive Hoist System

In order to avoid resonance, and to enhance safety of hoisting system and monitoring reliability, an impact mechanical model of mine hoisting rope for friction drive hoist system was built. According to Hamilton principle and considering the effect of oriented pulley and hoisting rope string, coupled extensional-torsional and extensional only mathematical models of hoisting rope were deduced. Mode shape and transcendental equation of angular frequency were obtained based on the hypothesis that the wave of vibration propagated with sine shape. With numerical calculation, results show that the frequency considering the effect of oriented pulley and hoisting rope string was slightly lower comparing with the frequency ignoring the effect at the bottom of shaft, but much different at the mouth; and there is significant difference between coupled frequency and extensional vibration only. Thereby, to make the design and monitoring of mine hoisting much more reliably, it is suggested that the extensional-torsional coupled vibration of hoisting rope, oriented pulley and hoisting rope string should be considered.

Realization and Performance of Serial Communication between Different Kinds of PLC

Communication between different kinds of Programmable Logic Controller (PLC), especially the Serial Communication (SC) between S7-300 and FX PLC, was investigated in this paper. The approach of SC between these two kinds of PLC was researched, and the communication performance was tested. On the basis of adequate analysis to the Programmable Port Protocol (PPP) of FX PLC, we designed the SC system structure, which was linking module CP340 of S7-300 to the programmable port of FX PLC with SC-08 programmable cable. And bidirectional semi-duplex SC was realized by configuration and programming to S7-300 PLC. In order to test the communication performance, we proposed a test scheme to measure the communication delay. The reading and writing communication delay were obtained, and the experimental result will be worked as reference when designing the networked control system in this communication structure.