Abstract
Virtual model control is a motion control framework that uses virtual components to create virtual forces/torques, which are actually generated by joint actuators when the virtual components interact with robot systems. Firstly, this paper employs virtual model control to do a dynamic balance control of whole body of quadruped robots' trot gait in a bottom controller. In each leg, there exists a designed swing phase virtual model control and a stance phase counterparts. In the whole body, virtual model control is utilized to achieve a attitude control containing roll, pitch and yaw. In the attitude control, a forces/torques distribution method between two stance legs is pre-investigated. In a high-level implemented controller, an intuitive velocity control approach proposed by Raibert is applied for the locomotion of quadruped robots. Secondly, an anti-disturbance control, which contains compensating gravity, adjusting step length, adjusting swing trajectory, adjusting attitude, and adjusting virtual forces/torques, is investigated to improve the robustness, terrain adaptability, and dynamic balance performance of quadrupedal locomotion. Thirdly, a trajectory tracking control method based on an intuitive velocity control is addressed through considering four factors: terrain complexity index, curvature radius of given trajectory, distance to terminal, and maximum velocity of quadruped robots. Finally, simulations validate the effectiveness of proposed controllers.
Highlights
Nowadays, legged robots have been a research hotspot and gained various attention [1]–[3]
Zero moment point (ZMP) has been a popular method to analyze the stability of legged robots [6], [7]
Boston Dynamics employed the idea of spring loaded inverted pendulum (SLIP) model to guide the locomotion of Bigdog [9]
Summary
Nowadays, legged robots have been a research hotspot and gained various attention [1]–[3]. Adding − τi on the lateral joint θ1 would produce a similar trunk roll control result as the virtual torque Tα It will cause a lateral force on the foot of stance leg, which will result in a unnecessary lateral movement. Combining equations (10),(11),(14),(15),(16),(17),(18),(19), the virtual model control of leg in stance phase can be concluded as: 1) the virtual forces along three axes are utilized to control the body RBO height, adjust the lateral velocity and forward direction; 2) extra torques − τi are added on the lateral joint θ1 to do the trunk roll control; 3) the pitch control is transferred to a translational control in z axis; 4) two inverse forward forces Fx are added on two stance legs to do the yaw control. An anti-disturbance control associated with virtual model control is essential
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
