AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |
Back to Blog
Webots static friction4/10/2023 ![]() Starting with the one legged hopper, a lot of control systems developed by using this SLIP model. On the other hand, dynamic walking of animals (or running) is modeled by SLIP technique. For this reason ZMP method is suitable for static walking. As a control technique ZMP relies on the idea of balancing all the moments of parts to the fixed contact point on ground by applying the actuation forces. These calculations can be done using some mathematical models such as ZMP (Zero Moment Point) or SLIP (Spring Loaded Inverted Pendulum). In both walking control techniques the leg positions, the joint speeds and the joint angles must be calculated continuously. The dynamically stable legged robots are more difficult to design and analyze than the static one, because of this reason the early development of legged robots focus on statically stable machines. Even much faster movements can be achieved with the dynamic walking, most of the researcher’s works on that area focused on static stability algorithms more than dynamic stability control techniques. The problem of controlling a dynamic system is much harder than that of controlling a static one. In the dynamic walking, there are some occasions that the COG-projecting point is outside the support polygon and that the static stability is broken during walking. Hence, the static stability is guaranteed during walking. In the static walking, the projection of the robot's CoG (Center of Gravity) is always inside the contact polygon. Legged locomotion can be categorized into static and dynamic walking. The researchers try to overcome the first problem by new actuator designs and optimization techniques on system parameters selection. Due to the improper selection of actuators or incorrectly adjusted system parameters, legged mobile robots may become less efficient. Legged mobile robots, by their nature, cannot work as efficiently as wheeled mobile robots. Researchers working on legged mobile robots generally focus on two main problems: the design and the control. According to a project in, 50% of the earth surface is unreachable for wheeled vehicles. demining or extra-terrestrial exploration missions) legged locomotion becomes an obligation. Even if the wheeled locomotion allows the robot to move quickly, it is not possible to use it everywhere because of the paved surface requirement. For that reason, it is necessary to investigate legged robots stability and walking conditions with large disturbances. Due to random surface of way, to follow prescribed trajectory with wheeled mobile robots is very difficult. In mobile robotic applications wheeled mobile robots, decreases the stability and make it difficult to follow prescribed trajectory with accuracy. Furthermore the proposed reference model on ODE system is always communication with IMU (Inertial Measurement Unit) sensor connected to mobile six legged robot’s body. ![]() The reference model which is employed in model based control system was assumed using ODE (Open Dynamics Engine) physical simulator. ![]() ![]() In this proposed algorithm a model based control system is used to implement posture control algorithm for the mobile robot stability control. This paper presents a posture control algorithm for balancing an experimental six-legged mobile robot against to external dynamic effects. Consequently, real-time application results of the six-legged mobile robot on a moving platform are observed and the results have shown better performance as depicted on graphs. For this reason, all the dynamic effects including externally applied forces to the real robot can be considered in the control process without making any assumptions. The reference model created on the ODE is always in communication with the IMU (Inertial Measurement Unit) sensor connected to the robot's body. The reference model used in model-based control was created using the ODE (Open Dynamics Engine) physics simulator. A model-based control structure is preferred in order to implement the posture control algorithm to the robot control. In this study, a posture control algorithm was developed to automatically balance a six-legged mobile robot against external dynamic effects such as incline or contact polygon changes. However, with the dynamic simulators developed in recent years, it has become possible to create dynamic models without making any assumptions. In order to model these complex dynamic structures, some assumptions must be made, such as no-friction, rigid links or non-redundancy. Legged locomotion systems, especially anthropomorphic mechanisms, can be modeled by using highly complex dynamic structures. ![]()
0 Comments
Read More
Leave a Reply. |