The compliant effect of controlled spine on interaction with the ground in quadruped trotting

Abstract

The spine plays important roles in the quadruped locomotion. These effects not only stand out in high-speed gait but also function in low-speed gait, especially the transition gait – trotting gait. In order to investigate the effects of the spine on the motion performance of the quadruped trotting, the spine with two joints is applied into the structure of the quadruped robot. This structure is inspired from the analyses for the canine, which imitates the configuration of thoracic vertebra, front lumbar vertebra and hind lumbar vertebra. Different from the quadruped robot with the passive spine or the active spine by inputting position, a compliant control is applied to the spinal joints. The feature of force control not only possesses the soft feature of the passive spine but also has the advantage of enlarging the motion ability. In the simulation process, a large amount of analyses are carried out including the influence of the control parameters of the controlled spine, the comparison with the quadruped robot with rigid torso and the gait simulation when the robot moves on the flat ground and across an obstacle. The results reveal that the controlled spine has an excellent compliant effect on the interaction with the ground. It contributes to reducing the ground reaction forces; meanwhile, the compliant effect is beneficial for improving the stability. By establishing the prototype robot and performing the motion experiment, the compliant effect of the spine is proven effective.

Multi-constraint spatial coupling for the body joint quadruped robot and the CPG control method on rough terrain

“…The foot-end coordinates in the single-leg coordinate system can be obtained by the coordinate transformation matrix B T L [10].…”

“…The rigid body quadruped robot is prone to movement instability, such as 'ground dragging' of the hind legs, oscillation of the body, and inability to adjust to terrain fluctuation. In contrast, the active body joint quadruped robot can effectively avoid this phenomenon [10][11][12].…”

Effect of Mass-Center Position of Spinal Segment on Dynamic Performances of Quadruped Bounding with a Flexible-Articulated Spine

“…The dynamics equation of continuous states is established completely according to the phase transitions of the leg shown in Figure 2 [18,19], but not the phase transitions of the quadruped robot [12], which makes the dynamics calculation more simple and convenient. Based on the Newton-Euler method, the dynamics equation of continuous states in state space can be presented as…”

High-speed running quadruped robot with a multi-joint spine adopting a 1DoF closed-loop linkage

“…Underactuated cable driving is a common method for coordinating the joint rotation of a spine structure, where cables are placed across multiple joints and driven by a number of actuators smaller than the number of joints ( Zhao et al., 2012 ; Seok et al., 2014 ; Eckert et al., 2015 ; Lei et al., 2022 ). Compared to the method of implementing actuators in each joint ( Eckert et al., 2020 ; Li et al., 2020 ), this method can reduce the number of actuators to match that of a single-joint spine structure, thereby reducing the weight of robot. Additionally, the actuators that drive the cables can be located distally relative to the moving parts of the spine structure, thereby making the spine structure more compact.…”