Wire Rope Tension Research Articles

Kalman-Filter-Based Sensor Integration of Variable Power Assist Control Based on Human Stiffness Estimation

In applications such as robot collaborating with human operators, the robot system must operate more slowly and be more compliant to safe user interaction. Moreover, a consideration of the dynamic properties of human operators is also important for the human application. According to such requirements, this paper presents a novel sensorless force control approach for the robot-assisted motion of the human arm. A twin direct-drive motor system with a wire rope has been developed to provide a precise force sensation and safety for human-robot interaction. In order to control the wire rope tension and human interaction force, two mode designs of the force control are realized. The common mode is utilized for the control of wire rope tension. In the differential mode, the Kalman-filter-based sensor integration for the interaction force observer is proposed in this paper. By combining two motor encoders and a commercial acceleration sensor together, white Gaussian noise is reduced, and high accurate feedback of the contact force is obtained. A variable power assist control method based on a real-time estimation of the stiffness of the human arm is also introduced. By considering the stiffness in human arm movements, this method increases the efficiency of the force control system and realizes comfortable force for human-robot interaction. The effectiveness of the method is verified by experimental results.

Effect of Tension on Friction Coefficient Between Lining and Wire Rope with Low Speed Sliding

Abstract In order to obtain the exact friction coefficient between lining and wire rope, the tension of wire rope is studied as a factor which affects this coefficient. A mechanical model of a wire rope subjected to axial load was established to determine the torque of the wire rope. The contact motion between lining and wire rope was regarded as a screw rotation and the axial force of the lining resulting from the torque of the wire rope was analyzed. Theoretical formulas relating tension of the wire rope and the friction coefficient was obtained. Experiments between lining and wire rope with low sliding speed were carried out with friction tester made by us. Experimental results show that increment of the friction coefficient is proportional to that of the tension of the wire rope with a low sliding speed. The experimental results agree with the theoretical calculation; the errors are less than 6%, which proves the validity of the theoretical model.

The influence of rope tension on the LMA sensor output of magnetic NDT equipment for wire ropes

There are many different wire rope constructions in service which are used in a diverse range of applications. Ropes will be discarded, not only because of faults (typically broken wires) and/or owing to other damage such as wear, corrosion and structural deformations. Almost every rope must be and is inspected in service. As a support to visual inspection, magnetic testing is accepted on a world wide basis, and is probably the most effective way for locating degradation. However, debate is ongoing about the quantitative interpretation of the measurements so obtained. The authors have previously published work assessing the reliability of a range of sets of NDT equipment on different ropes and forms of rope degradation. This paper is based on further research work which was sponsored by the British Council and the Polish State Committee for Scientific Research (KBN). It focuses on the problems associated with the accuracy of non-destructive testing of wire ropes by equipment which incorporates a loss of metallic area (LMA) sensor. (The LMA sensor is probably the most popular for quantifying the level of metallic area loss). The new issue discussed in this paper is the practical study of the effect of tension in the wire rope under test on the LMA signal output. The analysis considers the influence of wire rope tension on: equipment calibration; the position of the null base line of the Hall effect (LMA) sensor; and, readings from the LMA trace. The MD120 was used during these tests. The results provide practical information for the user about the accuracy of NDT inspection using NDT equipment with Hall effect LMA sensors.

運搬用鋼索の張力測定器の試作とその実用性について

運搬用鋼索の張力測定器の試作とその実用性について