Experimental Identification of Stress-Strain Material Models of UHMWPE Fiber Cables for Improving Cable Tension Control Strategies
Ultra-high-molecular-weight polyethylene fibers like Dyneema or Spectra are employed in a vast variety of cable-driven parallel robots. The stress-strain dynamics of such cables are highly non-linear with time-varying mechanical parameters, resulting in involved modeling and control of robot dynamics. To improve controllability of cable robots, the cable stress-strain dynamics need to be known and explicitly considered feedforward or closed-loop control. A model can only be deemed suitable, if its inherent dynamics is confirmed through experiments and if it allows for reasonable parameter estimation. We present results of experimental identification of stress-strain dynamics of UHMWPE cables made of Dyneema in different stages of operation. Due to the internal material mechanics, four stages can be identified: the tensing and relaxing transition as well as plateaus coming from either. The implications of verified and parametrized stress-strain models for cable robot tension control strategies is expedited.
KeywordsCable-driven parallel robots Cable strain UHMWPE fibers Dyneema
The authors Ph. T. and A. P. would like to thank the German Research Foundation (DFG) for financial support of the project within the Cluster of Excellence in Simulation Technology (EXC 310/2) at the University of Stuttgart.
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