| Guide dog robot(GDR)is an important power device used to guide the blind people to walk stably.It carries a variety of intelligent technologies.Among them,force interaction is a popular research area of GDR.Nowadays,there still exist problems with the fluency and experience of interaction between GDR and blind people.Therefore,this paper proposed a force interaction mode based on flexible cable,and established a coupling dynamic model of blind people,flexible cable and GDR.To maintain the tension at the end of flexible cable constant,this paper puts forward the vehicle control strategy of blind people under different walking conditions.Aiming at the existing problems of GDR force interaction,the research has achieved the following results:Firstly,based on the continuity of walking process,the rolling foot model of lower limb describing the motion of supporting leg was improved,and the whole walking process was modeled and analyzed;Based on the kinematic model of human lower limb rolling foot and upper limb multi-rod swing model,the kinematic model of human walking was established,and the speed output of COM and hand joint was realized;The experiment of capturing key markers with high-speed camera was carried out to obtain the speed of human COM and the hand joint in the walking process,and the accuracy of human walking kinematic model was verified.Secondly,based on the elastic catenary model,a flexible cable mechanic model was proposed,then its mathematical model was solved and analyzed by MATLAB software;The force transmission characteristics of rigid rod,spring and flexible cable as force interaction medium were studied,then the superiority of flexible cable as force interaction medium was proved;According to the actual demand of the project and the interactive experience demand of blind people,the flexible cable under different elastic modulus,linear density,cross-sectional area and other parameters was simulated and analyzed.The selection mechanism of flexible cable parameters was condensed.Thirdly,the longitudinal dynamic model of GDR was studied,and the transmission model between the motor torque output and the driving speed of GDR was constructed;According to the actual road driving demand,the rated power,torque,maximum speed and other parameters of the power plant were determined,and the parameter matching and selection mechanism of the driving motor were put forward;Based on the human walking kinematic model proposed in this paper,the human walking state was divided into three working conditions;According to the sensitivity requirements of the sensor,the effective interaction region is divided on the cable tension characteristic curve,and the characteristic curve in this region was Gaussian fitted;Based on this,the predicted basic motion control strategy of GDR was proposed.Finally,using the proposed basic motion control strategy of the GDR and taking the tension value at the end of the flexible cable as the feedback,the numerical simulation experiment was carried out under the common working conditions(general working condition,switching working condition and comprehensive working condition)that the human body walks.Both simulation and experiment realized the speed following of the blind people,which has verified the effectiveness of the control strategy. |
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