Cheetah Robot Research Articles

Attitude control in the Mini Cheetah robot via MPC and reward-based feed-forward controller

In this paper, a model-free approach, based on a generalization of unsupervised Self Organizing Feature Maps, is introduced to compensate for attitude control errors in a simulated mini cheetah quadruped platform. Traditional techniques mainly exploit the potentialities of convex model predictive control (MPC) to efficiently regulate the robot attitude while moving in unstructured environments. However, they are based on the knowledge of the analytical model of the robot. If the robot structure undergoes significant modifications due, for example to an unbalancing of the robot weight caused by a load charged of the robot center of mass, the added value of a model-free, adaptive unsupervised nonlinear controller, acting as a feed-forward error compensator, shows its real effect when integrated with the model-based approach. Moreover, the proposed solution, acting as a self-learning feedforward controller, contributes to the control action only when needed, preserving the basic performance of the ongoing MPC action. The design of the control scheme and simulation results will be reported, showing the impact of the introduced model-free compensation on the quadruped robot locomotion.

Energy-based analysis of bioinspired mechanism for cheetah robot leg

Energy-based analysis of bioinspired mechanism for cheetah robot leg

Geometrical synthesis method and parametric optimization of galloping robot leg mechanism

Subject of Research. The paper presents geometrical synthesis results of kinematic schemes for a femur and a whole leg mechanisms of a cheetah robot, which is able to jump in place and run at various speed. We substantiate the topology of mechanisms, describe their operation principles, characteristics and distinctive features, involving the controlled reconfiguration of mechanisms for changing the trajectory of the ground-contact point, and the use of flexible elements and links with variable length to ensure energy-efficient locomotion. Method. A structure scheme of the whole cheetah robot leg was obtained by attaching four movable links to the femur mechanism, imitating large and small tibial bones, metatarsus and sartorius muscle. The obtained structure was decomposed into three mechanism components: a “minitaur”, two-rocker four-bar lambda mechanism and a rocker-slider mechanism. The kinematic schemes of the above-mentioned mechanisms were synthesized by the method of extreme discrete positions with the result that the kinematic scheme of the whole leg with intermediate positions was obtained. The parametric optimization algorithm was described and the minitaur objective function was given using mathematical programming. Main Results. The kinematic scheme of the whole cheetah robot leg is obtained in the first approximation without taking into account the robot dynamics, location of flexible elements and their resonance necessary for the resonance behavior in order to achieve energy-efficient movement. Modeling results of the robot dynamics according to the synthesized scheme are given. Stable behavior is obtained both while jumping in place and running. Practical Relevance. The study is carried out for the development of an energy-efficient four-legged galloping cheetah robot performing energy recovery with the help of flexible elements. The synthesized kinematic scheme is applicable for detailed analyzes of dynamics, kinetostatics, energy recovery and losses upon impact with the ground surface, and for the robot prototype design.

Modeling and Simulation of Hexapod Kinematics with Central Pattern Generator

<span>The revealed secrets of nature always led humans to their aspiring achievements. The fastest animal on land is Cheetah and similar robot has developed by engineers so far to attain a record speed of 20mph among legged robots. But in nature there are some insects those are far ahead of cheetah in speed with a unit of body length per second. Insects are small in their body size with legs usually countable from 4 to 12 or more. With more legs they can have more stability and can adapt to different terrain faster while walking. Six legged robot (hexapod) is generally expect to attain higher speed in terms of body length per second, since the nature has proof for it. Bio-inspired Central Pattern Generator (CPG) is in use for so far in robotic world to mimic the locomotion patterns of insects and other animals. Currently the hybrid controller of CPG and reflex is going on and this paper suggests a new architecture for the system. Neural Network modeled CPG acts as the motor neuron for each joint of the leg. In each instant a neural network models the gait of the robot by learning procedure from the reflex system. This is like the Central Nervous System (CNS) selecting gait of an animal according to the terrain that travels. CNS takes sensory feedback from eyes, force on each leg and body balance from cochlea to adapt the gait for current terrain. This paper in first place tries to simulate the gait patterns for a hexapod.</span>

Control of a Cheetah Robot in Passive Bounding Gait

Passive dynamics is always one of research emphases of the legged robots. Studies have proved that cheetah robot could achieve stably passive bounding motion under proper initial conditions in the ideal case. However, the actual robot must have energy dissipation because of friction and collision compared with the theoretical model. This paper aims to propose a control method that can drive the cheetah robot running in passive bounding gait. First, a sagittal-plane model with a rigid torso and two compliant legs is introduced to capture the dynamics of robot bounding. Numerical return map studies of the bounding model reveal that there exists a large variety of passively cyclic bounding motions (fixed points). Based on the distribution law of fixed points, an open-loop control method including touchdown angle control strategy and leg length control strategy is put forward. At last, prototype of the cheetah robot is designed and manufactured, and locomotion experiment are carried out. The experiment results show that the cheetah robot can achieve a stable bounding motion at different speeds with the proposed control method.

Development of visual display with anti-vibration system for camera on MIT Cheetah robot

Development of visual display with anti-vibration system for camera on MIT Cheetah robot

Design Principles for Energy-Efficient Legged Locomotion and Implementation on the MIT Cheetah Robot

This paper presents the design principles for highly efficient legged robots, the implementation of the principles in the design of the MIT Cheetah, and the analysis of the high-speed trotting experimental results. The design principles were derived by analyzing three major energy-loss mechanisms in locomotion: heat losses from the actuators, friction losses in transmission, and the interaction losses caused by the interface between the system and the environment. Four design principles that minimize these losses are discussed: employment of high torque-density motors, energy regenerative electronic system, low loss transmission, and a low leg inertia. These principles were implemented in the design of the MIT Cheetah; the major design features are large gap diameter motors, regenerative electric motor drivers, single-stage low gear transmission, dual coaxial motors with composite legs, and the differential actuated spine. The experimental results of fast trotting are presented; the 33-kg robot runs at 22 km/h (6 m/s). The total power consumption from the battery pack was 973 W and resulted in a total cost of transport of 0.5, which rivals running animals' at the same scale. 76% of the total energy consumption is attributed to heat loss from the motor, and the remaining 24% is used in mechanical work, which is dissipated as interaction loss as well as friction losses at the joint and transmission.

The structural design, simulation analysis and parameter optimisation of the cheetah robot's leg components

The design and analysis of the cheetah robot's leg is directly associated with the bionic shape, bionic structure, bionic function and the bionic materials, even the bionic control. Adopting the essences of the cheetah skeleton system, we finish the design, the simulation and the optimisation of the bionic cheetah leg. After the strength, stiffness, stability, reliability and the durability are ensured, the basic shape and size are constructed according to the properties of functions and connections. After applying load, a finite element analysis (FEA) is carried out. According to the results of FEA, the design is well optimised. The methods described herein combines the advantages of CAD and CAE technology, which can significantly enhance not only the accuracy, rationality and speed during the design of the bionic cheetah robot's leg, but also the level of optimisation of biomimetic robots.

Key Technology Analysis of BigDog Quadruped Robot

The core technology of the Big Dog quadruped robot is analyzed. Adapting to the rough terrain is the main design clues of the Big Dog. Improving horizontal and vertical degrees of freedom linkage ability is the main innovation of structure design. Not good motion characteristics, such as robot's center of gravity ups and downs and self disturbance are the main reasons for being difficult to control. The components and advantage of the hydraulic power system are analyzed. Solving the driver problem of legged vehicles is the fundamental goal of the hydraulic system development. Supporting leg slipping or not, pitch and roll angle of the body too large or not are the main parameters as monitoring robot's movement condition. IMU and joint encoder can detect the state parameters of the body and limbs. Terrain of foot placement can be restored by pressure sensor. Three-in-one can build a virtual model. By the virtual model, robot's center of gravity and other key control process parameters can be calculated. At the same time, locomotion control system can do action drill roughly and accurate planning of kinematics or dynamics. The deviation of planning and prototype model is taken as the feedback for closed-loop control. LS3 constructs the navigation system of three-dimensional laser scanner and binocular vision as the main. LS3 can stride across rocky terrain by visual terrain reconstruction. Software system can integrate all the basic functions as an organic whole. Autonomy and intelligence of robot are discussed. Big Dog/LS3 and Curiosity Mars Rover are compared and analyzed. Big Dog has three big problems currently: instantaneously unable to increase hydraulic value significantly, all kinds of damage in mechanical transmission, bionic design not thoroughness. For the inadequacies of Big Dog, several improvements are analyzed on the LS3. Petman, Cheetah and Wildcat robot are briefly analyzed. Atlas biped robot has crash protection function and can recovery equilibrium status quickly after external force hitting by virtual model.

System Design of a Cheetah Robot Toward Ultra-high Speed

High-speed legged locomotion pushes the limits of the most challenging problems of design and development of the mechanism, also the control and the perception method. The cheetah is an existence proof of concept of what we imitate for high-speed running, and provides us lots of inspiration on design. In this paper, a new model of a cheetah-like robot is developed using anatomical analysis and design. Inspired by a biological neural mechanism, we propose a novel control method for controlling the muscles' flexion and extension, and simulations demonstrate good biological properties and leg's trajectory. Next, a cheetah robot prototype is designed and assembled with pneumatic muscles, a musculoskeletal structure, an antagonistic muscle arrangement and a J-type cushioning foot. Finally, experiments of the robot legs swing and kick ground tests demonstrate its natural manner and validate the design of the robot. In the future, we will test the bounding behaviour of a real legged system.

Animal Ontologies and Media Representations: Robotics, Puppets, and the Real of War Horse

Through examining the shift from the literary representation of the horse, to its depiction by puppets, to the cinematic “real” bodies onscreen in the production development of the film War Horse , this essay suggests that performance offers an imaginative space that can enable us to reconceptualize the interspecies relationships between the human and the nonhuman. It examines these performance spaces alongside technological developments that have revolved around the bodies of animals, interweaving the move in military developments from the live horse, to the tank, to the animal-shaped drone/robot. Tracing an interspecies reliance between humans and animals that has its roots in mechanical representations of animals, such as automata and the early cinematic exploration of animal bodies, the essay raises questions about the possibilities of performance to foster more collaborative interchanges between human and nonhuman animals. The reliance upon animal bodies in historical and current military development, such as DARPA’s hummingbird drone and Cheetah robot, have allowed technologized “animals” to replace humans in extreme situations, while engagement with the animal through the puppet form, despite its absence, reminds us of its presence.