Design and Research of All-Terrain Wheel-Legged Robot

Aiming at the crossing problem of complex terrain, to further improve the ability of obstacles crossing, this paper designs and develops an all-terrain wheel-legged hybrid robot (WLHR) with strong adaptability to the environment. According to the operation requirements in different road conditions, the robot adopts a wheel and leg compound structure, which can realize the transformation of wheel movement and leg movement to adjust its motion state. The straight and turning process of the robot is analyzed theoretically, the kinematics model is established and solved, and obstacle crossing analysis is carried out by establishing the mathematical model of front wheel obstacle crossing when the robot meets obstacles. To verify the analysis results, ADAMS software is used to simulate and analyze the process of robot running on the complex road surface and obstacles-crossing. Finally, a theoretical prototype is made to verify its feasibility. Theoretical analysis and experimental results show that the designed WLHR is feasible and has the stability of the wheeled mechanism and the higher obstacle crossing ability of the legged mechanism so that the robot can adapt to a variety of complex road conditions.

Design, Simulation and Fabrication of Quadrupedal Robot Integrated using Five-Jointed Legs with Suspension Spring

In this paper, a complete description of the design process for a four-legged locomotion robot or also known as quadrupedal robot will be presented. The quadrupedal robot is purposely designed as the Messenger Robot 2 (MR2) to participate in Robocon 2019. To overcome the challenges in Robocon 2019, each leg of the quadrupedal robot is designed with five joints integrated with a compression spring at the foot for suspension. The quadrupedal robot consists of a total sixteen standard servomotors where groups of four servos actuate leg joints of the quadrupedal robot. Furthermore, there are an additional three servomotors, where one servomotor is a joint at each front leg to allow the robot to rotate its orientation, and the last servo for an extension mechanism system. Finally, the simulation and experimental results demonstrated that the quadrupedal robot achieves a stable walking motion with the fastest locomotion of two legs contacting the ground at half walking cycle. In the future, the legged mechanism of the quadrupedal robot will be further improved and optimized toward the generalization of the dynamic legged locomotion in other challenging terrains.

Design and analysis of a novel multi-legged horse-riding simulation vehicle for equine-assisted therapy

A novel multi-legged horse-riding simulation vehicle aiming at providing the equine-assisted therapy is proposed, the functions of which include both transportation and rehabilitation. The whole system consists of a walking system constructed with four identical-legged units, a control system, an energy system, and a riding system. Based on the requirements of the foot trajectory, the configuration of the whole close-chain legged mechanism serving as a legged unit is designed with the structure of a single leg. The kinematics of the legged mechanism is built using the vector loop method, and the dimension is optimized adopting the sequence quadratic program. With the established mathematic model, the form-position inversion method is developed for the fluctuation analysis of the riding platform, and its modified algorithm is proposed according to the walking properties. The closed fluctuating curve group is obtained when the riding platform walks on a treadmill with a constant speed, and two functional curves are selected and analyzed for different walking modes. Combined with the practical requirements of different intensities, the sensitivity analysis is carried out for the reconfigurable process to adjust the fluctuation amplitude. A series of dynamic walking simulations are conducted and analyzed, and a prototype is fabricated to verify the expected functions of the multi-legged riding simulation vehicle. The study provides a new idea and an application reference for equine-assisted therapy system.

Kinematic effects of number of legs in 6-DOF UPS parallel mechanisms

SUMMARYIn this paper, we study the kinematic effects of number of legs in 6-DOF UPS parallel manipulators. A group of 3-, 4-, and 6-legged mechanisms are evaluated in terms of the kinematic performance indices, workspace, singular configurations, and forward kinematic solutions. Results show that the optimum number of legs varies due to priorities in kinematic measures in different applications. The non-symmetric Wide-Open mechanism enjoys the largest workspace, while the well-known Gough–Stewart (3–3) platform retains the highest dexterity. Especially, the redundantly actuated 4-legged mechanism has several important advantages over its non-redundant counterparts and different architectures of Gough–Stewart platform. It has dramatically less singular configurations, a higher manipulability, and at the same time less sensitivity. It is also shown that the forward kinematic problem has 40, 16, and 1 solution(s), respectively for the 6-, 3-, and the 4-legged mechanisms. Superior capabilities of the 4-legged mechanism make it a perfect candidate to be used in more challenging 6-DOF applications in assembly, manufacturing, biomedical, and space technologies.

Design and optimization of a dual quadruped vehicle based on whole close-chain mechanism

A new “whole close-chain mechanism” concept is proposed for the design of the modular legged unit of walking vehicles. Based on this concept, the walking vehicle called dual quadruped vehicle is developed and constructed. The vehicle designed as an omnidirectional carrying platform contains two identical single-driven quadruped mechanisms. The details of the design procedure are given, including the single close-chain legged mechanism, the modular legged unit, and the dual quadruped vehicle. The construction description of the single leg is presented. With the optimum design of the whole close-chain legged mechanism, the two foot-point characteristic trajectories are investigated. Based on the strategies of the legged module integration, the best phase configuration in pitching movement and the steering analysis are discussed and illustrated. Dynamic simulations and experiments are performed to verify the validity of the theoretical analysis of the new concept and the maneuverability of the vehicle prototype.

Workspace Analyzing for Hybrid Serial-Parallel Mechanism of a New Bionic Quadruped Robot

In this paper, a new bionic quadruped robot was proposed by us. The mechanism of robot we analyzed is as a hybrid series-parallel mechanism, so a new methods for constructing the kinematic model of the bionic quadruped robot very quickly and efficiently was introduced. we analyzed the workspace of the legged mechanism by using geometric composition method and numerical analysis method in the following section. Furthermore, the kinematic model of the parallel mechanism of the multi-motion mode bionic quadruped robot was constructed when the robot was in the stance phase, we also construct and solve the inverse kinematic model of the parallel mechanism of the robot, and the simulation results provide a better method for the robot’s workspace analyzing;Finally, the simulation experiment showed that the method we presented above could provide a good support for the multi-motion mode bionic quadruped robot walking smoothly and automatically.