仿落猫着陆特性的机器人任意姿态安全跌落机理及实现方法研究

The robots which work in the complex environmental conditions, such as planetary exploration, deep well rescue, military reconnaissance, have the danger to fall from the high places. It is important to solve the problem of safe landing when robots falling down. A cat has the interesting characteristics to right its body and land safely when it falls from high, because of its flexible spinal column and flexible legs and feet, which can be used in the robot landing system. To take the body structure and action feature of a cat as the research objects, the mechanism of automatic righting and safe landing with any posture of a falling cat will be researched. Based on the 3D spinal column-leg system, the kinematic model and the dynamic model of coupled rigid-flexible multibody will be built, the relationship of body’s bend/ twist, legs’ swing and the air attitude adjustment will be studied; the influence of the landing posture and the flexibility of body, legs, feet on landing stability will be revealed. The soft cables and springs will be used to design the flexible actuators. The active flexible spinal column mechanism, hip joint swing mechanism, leg buffer mechanism will be designed. The control strategy which combines trajectory planning and sensory feedback will be used, a self-adaptive system based on compliant mechanisms will be built, a four-legged robot imitating cat will be designed and optimized, and a prototype will be made. The project will reveal the laws of the safe landing of a robot falling from high, which will provide the theoretical basis and design experience of the safe landing system for the future design of four-legged robots. So it will further enlarge the application environments of robots.

机器人在星球探测、深井救援、军事侦察等复杂环境下工作时有从高处跌落的危险，解决机器人跌落安全问题尤为重要。猫从高处跌落时能够依据弹性脊椎骨、柔性腿足进行身体姿态变换并安全着地，这为机器人跌落安全仿生设计提供了有益的借鉴。本项目以猫的身体结构和动作特征作为研究对象，研究猫在任意姿态跌落过程中自动翻正并稳定着陆的内在规律；建立基于三维脊柱-腿系统的运动学和刚柔耦合多体动力学模型；探究躯干弯曲扭转、腿部偏摆与空中姿态调整的关系；揭示着陆姿态及躯干、腿、足的柔顺性对着陆稳定性的影响机制。利用软索、弹簧等柔性单元，设计主动柔顺脊柱机构、髋关节摆动机构、腿部缓冲机构，采用基于轨迹规划与传感相结合的反馈控制策略，建立基于柔顺机构的自适应系统，优化设计出一种仿猫四足机器人，制作出原理样机。项目成果将揭示机器人跌落安全机理，为以后的四足机器人跌落安全设计提供理论依据和经验积累，进一步扩大机器人的应用领域。

机器人在星球探测、深井救援、军事侦察等复杂环境下工作时有从高处跌落的危险，解决机器人跌落安全问题尤为重要。自由下落猫的身体结构和动作特征可为解决四足机器人的安全着陆问题提供有益借鉴。国内外学者就猫的自由下落原理已提出多种假设和计算模型，并在机器人上进行了初步应用，但并未对整个下落触地过程及四肢运动、柔性关节等对落猫运动的影响进行系统研究。本项目以猫的身体结构和动作特征作为仿生原型；首先，分析了使猫得以实现自动翻正安全着陆的生理特点和影响仿猫机器人安全跌落的因素；然后，基于角动量守恒定理分别建立了机器人翻正、俯仰过程的运动学模型，分析了弯腰、腰部扭转、腿部摆动等与空中姿态调整的关系；将落猫机器人的姿态控制问题转变成非完整系统的运动规划问题，分别建立能量最优及时间最优的优化模型，求解了系统的最优控制输入；基于经典碰撞理论和能量定理，建立了触地缓冲阶段的动力学模型，分析了着陆姿态及躯干、腿、足的柔顺性对着陆稳定性的影响；利用旋转关节的扭簧、腿部的线性弹簧等柔性单元，设计了仿猫机器人缓冲机构；最后，研制了试验样机，采用了基于轨迹规划与传感相结合的反馈控制策略，进行了实验分析。研究发现：不同的着陆姿态及躯干、腿、足的柔顺性将影响机器人的着陆稳定性、腿部受力、躯干加速度、关节扭矩等关键性能及参数；而弯腰、腰部扭转、腿部摆动等动作的合理规划可以有效调整着陆姿态，并达到减少能耗、减少调整时间的作用。上述研究成果能够为以后的四足机器人跌落安全设计提供理论依据和经验积累，同时对跳跃机器人、空投机器人、空间机器人的设计也有一定借鉴意义。