This paper proposes a novel legged locomotion principle for tracking the quadruped-robot base spatial motion which can generate automatically the trotting and walking gaits without flight phases. The principle is based on a new legged locomotion generator using the robot centroidal properties without a massless-leg assumption. Our quadruped robot is newly designed with symmetric legged dynamics properties using parallelogram mechanisms, and the corresponding generalized dynamics model is built. The centroidal momentum and dynamics models are established by combining the centroidal properties of the base and each leg, in which the virtual joint between the base and each leg CoM is used instead of the real joints. The stance legs follow the base motion with respect to contact constraints. The swing legs compensate for the delay influences (to centroidal motion) by the stance legs. By combining the whole-body kinematics model and the kinematics constraints relating to the contact constraints and the parallelogram mechanism, the adaptive swing-leg motion is achieved in the running process without pre-defined trajectories. When two swing legs land at different timings, the walking gait is applied. We also propose a new state machine for switching the locomotion gaits between walking and trotting, which also serves the torque controller which determines the dimension of the legged control states and the contact Jacobian. We apply our hierarchical torque controller to enable the robot with compliant dynamics properties. Therefore, our new locomotion principle integrates the system design, motion generation and whole-body torque control together, so that this one common framework is able to handle several locomotion gaits. To verify the usefulness and validity of our new locomotion principle based legged motion generator, we run several simulations: walking, trotting, turning, recovering from big lateral push force acting on the base.

本文提出了一种用于跟踪四足机器人基础空间运动的新型腿式运动原理，该原理可以自动生成没有飞行阶段的小跑和行走步态。该原理基于使用机器人质心属性的新型腿式运动发生器，而没有无质量腿假设。我们的四足机器人采用平行四边形机构新设计的对称腿动力学特性，并建立了相应的广义动力学模型。通过结合基部和每条腿的质心属性建立质心动量和动力学模型，其中使用基部和每条腿之间的虚拟关节 CoM 代替真实关节。站立腿根据接触约束遵循基本运动。摆动腿补偿站立腿的延迟影响（对质心运动）。通过结合全身运动学模型和与接触约束和平行四边形机构相关的运动学约束，在跑步过程中实现自适应摆动腿运动，无需预先定义轨迹。当两条摆腿在不同时间落地时，采用步行步态。我们还提出了一种新的状态机，用于在步行和小跑之间切换运动步态，它还为扭矩控制器提供服务，该控制器确定腿控制状态和接触雅可比矩阵的维度。我们应用我们的分层扭矩控制器来使机器人具有合规的动力学特性。因此，我们的新运动原理集成了系统设计，运动生成和全身扭矩控制结合在一起，使这个通用框架能够处理多种运动步态。为了验证我们新的基于运动原理的腿式运动发生器的有效性和有效性，我们运行了几个模拟：行走、小跑、转弯、从作用在底座上的大横向推力中恢复。