关键词: 四足机器人, 两自由度脊柱, 连续型脊柱, 被动柔顺性

Abstract: Due to the insufficient motion flexibility of quadruped robots, this paper designs a quadruped bionic robot with a two-degree-of-freedom continuous spine structure based on the characteristics of biological spines. By adopting the integrated design of spine units and limit mechanisms, the robot can maintain the bending ability of the spine at 45°in both the horizontal and vertical biaxial directions, and the motion performance of the robot is improved through the coordination of the spine and the legs. A coordinated kinematic model of the spine-leg is established based on coordinate transformation and the improved Modified Denavit-Hartenberg (MDH) method. It is calculated that the spine can expand the working space of the front leg foot by 2.0 times in the horizontal direction and 0.91 times in the vertical direction. The test experiments show that the continuous spine robot can achieve biaxial bending motion within the range of 0~30°, and the maximum error of angle control does not exceed 3°. The spine reduces the forward turning radius by 37%, which can effectively assist the quadruped robot in turning. In the bound gait experiment, the shortest distance between the legs is 474.7 mm, and the longest distance reaches 861.6 mm, which is 1.47 times the body length (586.6 mm), verifying the advantages of the bionic spine in expanding the motion space.

Key words: quadruped robot, two-degree-of-freedom spine, compliant spine, passive compliance