Some light materials, such as hollow sphere composite (HSC), carbon fiber reinforced plastic (CFRP), and aluminum alloy (AA), are currently used in the design of lightweight robotic arms. However, the high cost limit the use of HSC, the CFRP has a relatively low cost but poor processing property, and the AA has good processing property but relatively high density. To make up respective shortcomings, this study focuses on the design issues of lightweight robotic arms by using two kinds of materials. Based on the CFRP and AA, a hybrid structure design approach is proposed to minimize the total mass of the lightweight robotic arms with CFRP/AA hybrid structure. To accomplish the objective, structural dimensions and layer parameters in hybrid structures are parameterized as design variables subject to the strength, stiffness, and dynamic constraints. Moreover, the bonding strength of the interaction surfaces between CFRP and AA parts is also considered on the basis of the cohesive zone model (CZM). In optimization design, the ABAQUS and elitist non-dominated sorting genetic algorithm (NSGA-II) in modeFRONTIER utilizing the Python script are respectively employed for the structural analyses and iteration calculation. Finally, a design example and an experimental prototype are provided to validate the proposed method and compare with the previous AA prototype in mass with a reduction of 24.32%.INDEX TERMS Lightweight robotic arm, hybrid structure, optimization design, carbon fiber reinforced plastic, aluminum alloy.
The dynamic processes of a flexible manipulator consist of flexible and rigid motion components. The dynamic equations expressing the motion can be divided into two corresponding subsets, and a decomposed dynamic control (DDC) is proposed for the design of a controller for a flexible manipulator. The DDC is composed of flexible dynamic control and rigid dynamic control: the flexible dynamic control involves developing a desired trajectory through considerations of the physical properties of the device based on a feed-forward strategy; the rigid dynamic control aims at tracking the desired trajectory based on a feedback strategy. This report mainly investigates the flexible dynamic control which searches for a desired trajectory considering nonlinearity. An optimization method applying the Nelder-Mead simplex (NM) algorithm is proposed to obtain the desired trajectory. Numerical simulation and experimental results show that the optimization can deal with the extremely nonlinear problems. Additionally, the conclusion that optimization is strongly dependent on the accuracy of the model is possible, for further research, a more robust controller will be investigated.
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