控制步行机足运动的一种方法—修正组合摆线法

基于接近感器所获得的地面信息，研究腿在转移支撑点时运动的控制问题，提出用“修正组合摆线”作为足的运动轨迹，解决足对不平地面的自适就问题。从而避免了腿的急动和足与地面间的冲击，并且使不平地面的自适应步态成为简单的周期步态。     

一种六足步行机器人的自由步态算法

本文探讨了适用于六足步行机器人的步态类型和机器人腿运动的三个约束条件,提出了一种适用于六足步行机器人在不规则地形上运动的自由步态算法.机器人在大部分的地形状况下以标准模式行走.当标准模式失效时,则采用自适应模式,对机器人状态进行调整,以实现正常的行走运动.在保证运动速度和能量效率的前提下,使机器人具备良好的地形适应能力.最后,文章给出了算法的程序流程图,并在MATLAB下进行了仿真验证.     

基于改进蚁群算法的四足机器人步态规划

四足机器人关节众多、运动方式复杂,步态规划是四足机器人运动控制的基础。传统的算法多基于仿生原理,缺乏广泛适应性。 在建立运动学方程的基础上,提出了一种基于改进蚁群算法的步态规划算法。该算法利用了四足机器人4条腿运动的线性无关性,将步态规划问题转换为在四维空间里求取最长路径问题。仿真结果表明,该算法得出了满足约束条件的所有步态,最后通过机器人样机检验,验证了该算法求取结果的有效性和合理性。     

四足机器人步态生成算法研究与仿真

在四足机器人行走动态控制的研究中,为使四足机器人能在复杂地面状况下行走,提出了一种四足机器人在不平坦地面爬行时的平动步态生成算法.首先构建四足机器人步行机构模型,根据静态稳定性对角线原理的判定确定机器人腿的摆动顺序;以平动步态为例根据机器人前行方向、初始位姿、地面不平坦等因素计算一个步态周期后机器人的位姿从而实现平动直线行走的连续步态算法.考虑了机器人机构约束以及状态变化因素使机器人在每一个步态周期都能跨出尽可能大的步幅实现行走效率的最大化.通过仿真验证了算法的正确性.仿真结果对四足机器人步态稳定性的研究及实现具有实际的参考价值.     

控制六足仿生机器人三角步态的研究

基于仿生学原理,在分析六足昆虫运动机理的基础上,对六足仿生机器人的三角步态运动原理进行了分析.论文涉及六腿机器人步态研究的一些基本参数的描述,讨论了用相对运动的原理研究步态的方法,结合慧鱼机器人组合包中的构件拼出六足仿生机器人.该机器人模型结构简单,设计独特,能前进和后退,且能避开小型障碍物.基于三角步态运动原理对其进行了反复实验,实验结果表明六足仿生机器人具有较好的机动性和稳定性.     

步行机器人的研究

1.首先介绍了步行机步态的定义及四足步行机的对称规则步态,在此基础上,对四足步行机稳定性问题进行了深入的研究,提出了基于能量考虑(计入运动速度影响)稳定性分析计算的能量法.2.详细讨论了运动主平面与垂直旋转轴具有偏距的圆柱型空间缩放式腿机构运动学,对四足步行机进行了与运动学控制有关的运动分析,给出了步行机运动速度与步态之间的关系,机体速度加速度与足端速度加     

基于静平衡的四足机器人直行与楼梯爬越步态

为提升四足机器人的障碍爬越能力,采用稳定裕度作为四足机器人静态稳定的判据,以落足点形成的 象限边界明确了不同初始位姿机器人的迈腿可能性．基于迈腿次序将所有步态划分为24 种类型．利用运动空间需 求最小、稳定裕度最大、步态协调性最好3 个基本评价指标,对四足机器人的24 种基本步态进行了对比分析．提出 了基于投影分析法结合平面静平衡步态理论的楼梯爬越步态研究方法,并以上述3 个特性参数最佳为要求,对楼梯 爬越步态进行了系统仿真,所得结果为四足机器人的直行与楼梯爬越步态选择提供了理论依据．实验表明了所研究 方法的有效性．     

基于主支撑腿运动优化的仿人机器人快速步态规划算法

提出一种基于主支撑腿运动优化的快速步态规划算法，利用快速动态步行的特点，规划ZMP(Zero Moment Point)适时地离开质心投影并始终停留在稳定的支撑区域内．规划过程中考虑了仿人机器人摆动足触地时的碰撞，整个步态产生于深度的优化过程．     

具有2DOF铰接式躯干的仿猎豹四足奔跑机器人

为了探索脊柱运动对腿运动的增强机理,设计了具有2自由度铰接式躯干的仿猎豹四足奔跑机器人。对带腾空相的跳跃（bound）步态奔跑运动的力学过程进行描述,采用阻尼型弹性负载倒立摆（D-SLIP）模型建立了四足机器人动力学模型。依据猎豹的奔跑运动模式,对四足机器人脊柱关节与腿关节的耦合运动进行了轨迹规划。提出一种改进的粒子群优化（PSO）算法,解决了机器人脊柱关节驱动机构尺寸和运动轨迹控制参数之间目标互斥的嵌套优化问题。对四足机器人跳跃奔跑运动进行动力学仿真,结果表明：脊柱与腿的协调运动可以增大奔跑步幅,使机器人产生腾空相,从而提高机器人的奔跑速度。     

基于CPG的六足机器人运动步态控制方法

中枢模式发生器（CPG）在六足机器人的运动步态控制中起着至关重要的作用。为了研究六足机器人的运动控制方法,首先基于仿生学原理设计了六足机器人的机械结构,并在虚拟样机软件ADAMS中搭建其三维模型;其次选择Hopf振荡器作为CPG单元,并改进了振荡器模型;然后设计了六足机器人的CPG网络拓扑结构,包含单腿关节映射函数方案和腿间CPG环形耦合网络方案,并对其进行了改进;最后通过ADAMS和MATLAB联合仿真实验,验证了所设计六足机器人的运动稳定性和CPG控制方案的可行性与有效性。仿真结果表明,该方法能够满足六足机器人不同运动步态的控制需求,对六足机器人的运动控制具有一定的实际应用价值。     

Fault-Tolerant Gait Planning for a Hexapod Robot Walking over Rough Terrain

Multi-legged robots need fault-tolerant gaits if one of attached legs suffers from a failure and cannot have normal operation. Moreover, when the robots with a failed leg are walking over rough terrain, fault-tolerance should be combined with adaptive gait planning for successful locomotion. In this paper, a strategy of fault-tolerant gaits is proposed which enables a hexapod robot with a locked joint failure to traverse two-dimensional rough terrain. This strategy applies a Follow-The-Leader (FTL) gait in post-failure walking, having the advantages of both fault-tolerance and terrain adaptability. The proposed FTL gait can produce the maximum stride length for a given foot position of a failed leg and better ditch-crossing ability than the previous fault-tolerant gaits. The applicability of the proposed FTL gait is verified using computer graphics simulations.     

Generation of a continuous free gait for quadruped robot over rough terrains

Generating a robust gait is one of the most important factors to improve the adaptability of quadruped robots on rough terrains. This paper presents a new continuous free gait generation method for quadruped robots capable of walking on the rough terrain characterized by the uneven ground and forbidden areas. When walking with the proposed gait, the robot can effectively maintain its stability by using the Center of Gravity (COG) trajectory planning method. After analyzing the point cloud of rough terrain, the forbidden areas of the terrain can be obtained. Based on this analysis, an optimal foothold search strategy is presented to help quadruped robot to determine the optimum foothold for the swing foot automatically. In addition, the foot sequence determining method is proposed to improve the performance of robot. With the free gait proposed in this paper, quadruped robot can walk through the rough terrains automatically and successfully. The correctness and effectiveness of the proposed method is verified via simulations.     

A desired landing points walking method enablinga planner quadruped robot to walk on rough terrain

It is necessary for legged robots to walk stably and smoothly on rough terrain.In this paper,a desired landing points(DLP) walking method based on preview control was proposed in which an off-line foot motion trace and an on-line modification of the trace were used to enable the robot to walk on rough terrain.The on-line modification was composed of speed modification,foot lifting-off height modification,step length modification,and identification and avoidance of unsuitable landing terrain.A planner quadruped robot simulator was used to apply the DLP walking method.The correctness of the method was proven by a series of simulations using the Adams and Simulink.     

A fault tolerant gait for a hexapod robot over uneven terrain

The fault tolerant gait of legged robots in static walking is a gait which maintains its stability against a fault event preventing a leg from having the support state. In this paper, a fault tolerant quadruped gait is proposed for a hexapod traversing uneven terrain with forbidden regions, which do not offer viable footholds but can be stepped over. By comparing performance of straight-line motion and crab walking over even terrain, it is shown that the proposed gait has better mobility and terrain adaptability than previously developed gaits. Based on the proposed gait, we present a method for the generation of the fault tolerant locomotion of a hexapod over uneven terrain with forbidden regions. The proposed method minimizes the number of legs on the ground during walking, and foot adjustment algorithm is used for avoiding steps on forbidden regions. The effectiveness of the proposed strategy over uneven terrain is demonstrated with a computer simulation.     

Hazard avoidance for high‐speed mobile robots in rough terrain

Unmanned ground vehicles have important applications in high speed rough terrain scenarios. In these scenarios, unexpected and dangerous situations can occur that require rapid hazard avoidance maneuvers. At high speeds, there is limited time to perform navigation and hazard avoidance calculations based on detailed vehicle and terrain models. This paper presents a method for high speed hazard avoidance based on the “trajectory space,” which is a compact model‐based representation of a robot's dynamic performance limits in rough, natural terrain. Simulation and experimental results on a small gasoline‐powered unmanned ground vehicle demonstrate the method's effectiveness on sloped and rough terrain. © 2006 Wiley Periodicals, Inc.     

Negotiating Uneven Terrain with a Compliant Designed Unmanned Ground Vehicle Equipped with Locomotive Master‐Slave Operation

In recent years, a number operational unmanned ground vehicles (UGVs) have been developed that can negotiate irregular terrain. They have a number of degrees‐of‐freedom (DOF) giving them enhanced mobility, e.g., the ability to climb stairs and over obstacles. However, operating them remotely is complicated because their controllers are similar to conventional control pads or joysticks used in computer games or toys. It is hard for the operator to achieve an intuitive and natural feel, thus mistakes are common. To intuitively control the locomotion of a UGV with many DOFs, a master‐slave operation was implemented. A novel UGV called Kurogane, which consists of a typical crawler combined with a human‐like torso section, was developed. The torso section is controlled via a wearable controller interface. In addition, the UGV is equipped with models of muscle viscoelasticity and stretch reflex, called the involuntary autonomous adaptation system, inspired by the adaptive compliance of animals. The proposed system can autonomously and flexibly react and adapt to irregular terrain in real time. Therefore, the operation of Kurogane is simple and does not require great skill or precision. Experimental results show that it performs well over a fixed step, stairs, and rough outdoor terrain. © 2013 Wiley Periodicals, Inc.     

Development of a control system for an omni-directional vehicle with step-climbing ability

This paper proposes a control method for wheels to pass over rough terrain. In our previous work, we have developed a holonomic mobile mechanism capable of running over steps. The mechanism realizes omni-directional motion on a flat floor and passes over uneven ground in forward and backward directions. The vehicle has seven special wheels with cylindrical free rollers and two passive body axes that can adapt to rough terrain. Seven actuators are located in each wheel; therefore, our vehicle system requires the rotation velocity of each wheel to be coordinated. However, it is difficult to keep such coordination among the wheels — as the vehicle passes over the step, the load applied to the wheel tends to heavy and irregular. Therefore, we propose a new control system for synchronization among the wheels. In this paper, the following two topics are discussed: the load adjustment so as not to exceed the maximum torque of the actuator in some of the wheels and keeping the balance of rotation velocity among the wheels. Our novel control method adjusts the output value by referring to the state of the other wheels. The performance of our system is investigated by means of computer simulations and experiments using our prototype vehicle.     

Foot Force Based Reactive Stability of Multi-Legged Robots to External Perturbations

Many environments and scenarios contain rough and irregular terrain and are inaccessible or hazardous for humans. Robotic automation is preferred in lieu of placing humans at risk. Legged locomotion is more advantageous in traversing complex terrain but requires constant monitoring and correction to maintain system stability. This paper presents a multi-legged reactive stability control method for maintaining system stability under external perturbations. Assuming tumbling instability and sufficient friction to prevent slippage, the reactive stability control method is based solely on the measured foot forces normal to the contact surface, reducing computation time and sensor information. Under external perturbations, the reactive stability control method opts to either displace the CG or the foot contacts of the robot based on the measured foot force distribution. Details describing the reactive stability control method are discussed including algorithms and an implementation example. An experimental demonstration of the reactive stability control method is presented. The experiment was conducted on a hexapod robot platform retrofitted with a tiny computer and force sensitive resistors to measure the foot forces. The experimental results show that the presented reactive stability control strategy prevents the robot from tipping over under external perturbation.     

A terrain-following control approach for a VTOL Unmanned Aerial Vehicle using average optical flow

This paper presents a nonlinear controller for terrain following of a vertical take-off and landing vehicle (VTOL). The VTOL vehicle is assumed to be a rigid body, equipped with a minimum sensor suite (camera, IMU and barometric altimeter) maneuvering over a textured rough terrain made of a concatenation of planar surfaces. Assuming that the forward velocity is separately regulated to a desired value, the proposed control approach ensures terrain following and guarantees that the vehicle does not collide with the ground during the task. The proposed control acquires an optical flow from multiple spatially separate observation points, typically obtained via multiple cameras or non collinear directions in a unique camera. The proposed control algorithm has been tested extensively in simulation and then implemented on a quadrotor UAV to demonstrate the performance of the closed-loop system.     

Development of vehicles with legs and wheels

This paper deals with the design of the foot trajectory for a quadruped walking machine. Such walking machines should be capable of both uneven terrain walking and high-speed flat surface walking. The static walking method was used for uneven terrain walking and the dynamic walking method was used for plane walking. In the case of dynamic walking, the relative speed between the foot and the ground causes instability in the balance of the body. A foot trajectory is designed based on two points: the kinematics of foot motion and the relationship between joint motion and joint driving torque. A method for reducing the impact force upon initial contact with a floor by designing a periodic foot trajectory based on the wave motion of a cam is discussed. In this method, vertical and horizontal motions of the foot trajectory were generated independently using cycloidic motion. We named this trajectory the composite cycloid foot trajectory. We further developed a modified cycloidic foot trajectory by smoothing the joint angular acceleration.