Abstract
In order to effectively plan the robot gaits and foot workspace trajectory (WT) synchronously, a novel biologically inspired control strategy for the locomotion of a quadruped robot based on central pattern generator—neural network—workspace trajectory (CPG-NN-WT) is presented in this paper. Firstly, a foot WT is planned via the Denavit-Hartenberg (D-H) notation and the inverse kinematics, which has the advantages of low mechanical shock, smooth movement, and sleek trajectory. Then, an improved central pattern generator (CPG) based on Hopf oscillators is proposed in this paper for smooth gait planning. Finally, a neural network is designed and trained to convert the CPG output to the preplanned WT, which can make full use of the advantages of the CPG-based method in gait planning and the WT-based method in foot trajectory planning simultaneously. Furthermore, virtual prototype simulations and experiments with a real quadruped robot are presented to validate the effectiveness of the proposed control strategy. The results show that the gait of the quadruped robot can be controlled easily and effectively by the CPG with its internal parameters; meanwhile, the foot trajectory meets the preplanned WT well.
Highlights
Compared with wheeled robots, quadruped robots with their good environmental adaptability and motion flexibility have become a research hot spot in recent years [1,2,3,4,5,6,7]
The typical central pattern generator (CPG) models for legged robots’ locomotion control can be roughly divided into three categories: CPG model based on neuron oscillators, CPG model based on nonlinear oscillators and other kinds of CPG model
CPG-NN-workspace trajectory (WT)-based shown in where the its components andvalidity configurations are the same as described in control strategy, the virtual prototype simulation based on Webots and the experiments with a real
Summary
Compared with wheeled robots, quadruped robots with their good environmental adaptability and motion flexibility have become a research hot spot in recent years [1,2,3,4,5,6,7]. Most of the previous studies focused on the CPG model concerned with the CPG output waveform and the inter-coordination of the joints within a leg to and its structure and connection topological relations, while only few studies were concerned with the meet the desired foot WT [4]. The general operation operation mode while using WT-based control strategy is: firstly, planning a foot WT with a specific mode while using WT-based control strategy is: firstly, planning a foot WT with a specific advantage; advantage; secondly, solving the intra-leg joints’ coordinated function via inverse kinematics; secondly, solving the intra-leg joints’ coordinated function via inverse kinematics; coupling coupling the legs in an “up layer” through certain phase relationships to obtain the relative the legs in an “up layer” through certain phase relationships to obtain the relative gait
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