Posture and Vibration Control Based on Virtual Suspension Model for Multi-Legged Walking Robot

Until now, studies on suspension control by using frequency response analysis that have been reported are almost for motorcar, but not for multi-legged walking robot. However, because of the disturbances, such as the various frequency properties of terrain, the collision and the slip between foot of robot and ground, the dynamic changes of the supported weight by each leg and the centre of gravity of robot with the change of the walking pattern, tiny vibration of robot's body occur when robot walks, especially on rough terrain. This tiny vibration can become unstable big vibration when the above disturbances to the posture of robot exist, which will influence normal walk and work of robot. Recently there are some studies about the posture control of multi-legged walking robot (Shin-Min Song & Keneth J.Waldron, 1989); (Kan Yoneda, et al, 1994); (Qingjiu Huang, et al, 2000); (Qingjiu Huang & Kenzo Nonami, 2002); (Qingjiu Huang, et al, 2003), but no any study on the tiny vibration control of robot's body. Moreover, only posture control can not effectively decrease the tiny vibration of body when robot walks, especially on rough terrain. Therefore, it is necessary to study suspension and its control algorithm to decrease the tiny vibration of body for multilegged walking robot. In this chapter, we treat a six-legged walking robot as a study example of the multi-legged walking robot, and introduce the newest study on a control for the posture and vibration of the robot using suspension mechanism to realize the better stability and the better adaptability of its walking for unknown rough terrain. On the other hand, until now most reported studies on suspension control are performed on the basis of real suspension model with spring and damper (Nurkan Yagiz, et al, 2000); (Makoto Yokoyama, et al, 2001). However, for large scale multi-DOF system, such as multilegged walking robots, it is difficult to equip lots of springs and dampers to the robot. Therefore, in this chapter, we introduce a new control method for the posture and vibration of the six-legged walking robot (Qingjiu Huang, et al, 2007), which is based on not a real suspension model but a virtual suspension model consisting of virtual spring and damper. And then considering the nonlinear disturbances and trade-off problem in the design of suspension, a robust control using sliding mode control based on the constructed virtual suspension model for the posture and vibration of the six-legged walking robot is proposed and introduced. O pe n A cc es s D at ab as e w w w .ite ch on lin e. co m