Leg-wheel Mobile Robot Research Articles

A Low-Energy Consumption Planning Method for Multi-Locomotion Wheel-Legged Mobile Robots

Mobile robots can replace humans to fulfill tasks in dangerous environments, which has been a research focus in recent years. This paper proposes a wheel-legged mobile robot with multi-locomotion and a low-energy consumption planning method. Different from the existing wheel-legged mobile robots, it can realize low-energy movement in different terrains with simple structures, and it can realize three modes: synchronous, tumbling, and curl–stretch. Then, based on the kinematics and dynamics model, a low-energy planning method is proposed, and low-energy motion planning is carried out for the three modes to obtain the low-energy driving law in each mode. A robot prototype is developed, and the experimental results show that the robot can move through the three modes with lower energy consumption in all three terrains. The planning method provides an effective reference for applying wheel-legged mobile robots.

Design, Analysis, and Experiment of a Wheel-Legged Mobile Robot

In this paper, a wheel-legged mobile robot is proposed. The parameter design of the wheel-leg structure is completed using geometric analysis and statics modeling. The curling mechanism is chosen as the main part of the robot, expanding the robot’s application scenarios. Particle swarm optimization is used to determine the number of body sections and their length. After dynamic simulation, rubber is selected as the wheel-leg cover material. Based on the above results, a prototype is made and subject to experiments in different terrains. The experiment results verify that the robot is adaptable to multiple terrains with strong obstacle-crossing ability.

Design and Analysis of Transformable Wheel-legged Mobile Robot

Wheeled mobile robot has good ground motion ability, fast moving speed and low energy consumption, but poor obstacle surmounting performance. In order to make the mobile robot have the motion performance in complex environments, the wheel mechanism and the wheel-leg mechanism are coupled and designed, and a deformable wheel-leg structure is designed. The mobile robot can not only move in the wheel mode, but also switch to the wheel-leg mode to adapt to the complex motion environment. The deformable wheel-leg mechanism is composed of a four-bar linkage, and the static analysis of key components is carried out in ANSYS.

Analysis of Motion Characteristics and Stability of Mobile Robot Based on a Transformable Wheel Mechanism

In this research, we propose a novel wheel-legged mobile robot to address the problems of insufficient obstacle-crossing performance and poor motion flexibility of mobile robots in non-structural environments. Firstly, we designed the transformable wheel mechanism and tail adaptive mechanism. Secondly, the kinematic model of the robot is established and solved by analyzing the whole motion and wheel-legged switching motion for the operation requirements under different road conditions. By synthesizing the constraint relationships among the modules and analyzing the robot’s obstacle-crossing abilities, we systematically established the mechanical model of the robot when it encounters obstacles. Thirdly, we studied the stability of the robot based on the stable cone method in the case of slope and unilateral transformation wheel deployment and achieved the tipping condition in the critical state. Finally, we used ADAMS software to simulate and analyze the driving process of the robot in various types of terrain and obstacles in order to verify that it has superior performance through obstacles and motion flexibility. The analysis shows that the robot can passively adapt to various complex and variable obstacle-filled terrains with obstacle heights which are much higher than its center of gravity range. The results of the study can provide a reference for the structural optimization and the obstacle-crossing performance improvement of mobile robots.

Configuration Design and Gait Analysis of Wheel-Legged Mobile Robot Based on the Rubik’s Cube Mechanism

In order to improve the obstacle-crossing ability, motion stability and load-bearing capacity of mobile robots for different terrains, the Rubik’s Cube mechanism (RCM) with strong coupling and variable topology is introduced into the field of mobile robots, and a wheel-legged mobile robot (WLMR) based on RCM is proposed. Aiming at the problems of the classical three-order RCM, such as small internal space, difficult processing and demanding precision, a new type of chute third-order RCM is designed, and its mechanical characteristics analysis and feasibility analysis are carried out. What’s more, a driving configuration analysis method is established according to different driving configuration relationships, and the configuration of WLMR is determined by the configuration stability analysis. Then, a WLMR with polymorphism is designed, and gait planning and gait stability analysis are conducted. Eventually, the co-simulation and prototype experiments are performed to verify the efficiency of the WLMR’s straight motion, in-situ rotation, obstacle-crossing and morphology transformation in complex environments. This research not only provides a reference for the design of polymorphous mobile robots, but also opens up ideas for the application of the RCM in daily production and life.

Design and motion analysis of reconfigurable wheel-legged mobile robot

An adaptive wheel-legged shape reconfigurable mobile robot, based on a scissor-like mechanism, is proposed for an obstacle detecting and surmounting robot, moving on complex terrain. The robot can dynamically adjust its own shape, according to the environment, realizing a transformation of wheel shape into leg shape and vice versa. Each wheel-legged mechanism has one degree of freedom, which means that only the relative motion of the inner and outer discs is needed to achieve the transformation of the shape into a wheel or a leg. First, the force analysis of the conversion process of the wheel-legged mechanism is carried out, while the relationship between the driving torque and the friction factor in the non-conversion trigger stage and in the conversion trigger stage is obtained. The results showed that the shape conversion can be better realized by increasing the friction factor of the trigger point. Next, the kinematics analysis of the robot, including climbing the obstacles, stairs and gully, is carried out. The motion of the spokes tip is obtained, in order to derive the folding ratio and the surmountable obstacle height of the wheel-legged mechanism. The parameters of the wheel-legged structure are optimized, to obtain better stability and obstacle climbing ability. Finally, a dynamic simulation model is established by ADAMS, to verify the obstacle climbing performance and gait rationality of the robot, in addition to a prototype experiment. The results showed that the surmountable obstacle height of the robot is about 3.05 times the spoke radius. The robot has the stability of a traditional wheel mechanism and the obstacle surmount performance of a leg mechanism, making it more suitable for field reconnaissance and exploration missions.

Kinematic modelling and analysis of single leg in hybrid wheel-legged mobile robot

Mobile manipulators are extensively used in various applications. Most of the mobile manipulators are built on a wheeled mobile platform. A wheeled mobile platform performs well on flat terrains but is not suitable for navigation in rough terrains. The legged robots are commonly used for rough terrain applications. However, the navigation speed of legged robots is lesser than wheeled mobile robots. This paper focuses on the development of hybrid wheellegged robots to overcome the above difficulties. The proposed model is quadruped with five degrees of freedom in each leg. The development of the kinematic model, its dimensional synthesis, and motion study for a single leg is presented in detail. DH-conventions are used for kinematic modelling, manipulability index is used for dimension synthesis, and motion study is carried out in ADAMS.

Design of Kinematic Mechanism of Wheel-legged Robot

Mobile robots can be roughly categorized in wheeled type, tracked-skidded type, legged type, trunked type, etc. Among them, the wheeled mobile robot can move on the flat road, but with poor performance when crossing an obstacle; the legged type mobile robot has a slow motion speed and poor bearing capacity; the tracked-skidded mobile robot has a large weight; while the trunked mobile robot has limited use occasions. In order to overcome these shortcomings, this paper studies the wheel-legged structure and distributes the performance of various commonly used structures. On the other hand, by analyzing the newly emerged structure, the impact of the organization’s own shortcomings on performance is hoped to be reduced. By comparing the structure and distribution of different leg configurations, the advantages of the locomotion performance of each type of wheel-legged mobile robot and the development trend of the wheel-legged mobile robot in the future are analyzed.

Simplification of Motion Generation in the Singular Configuration of a Wheel-Legged Mobile Robot

Simplification of Motion Generation in the Singular Configuration of a Wheel-Legged Mobile Robot

A transformable wheel-legged mobile robot: Design, analysis and experiment

This paper proposes a new type of transformable wheel-legged mobile robot that could be applied on both flat and rugged terrains. It integrates stability and maneuverability of wheeled robot and obstacle climbing capability of legged robot by means of a wheel-legged transformable mechanism. These two modes can be switched easily with two spokes touching terrain. In this paper, the motion analysis of the proposed robot under wheeled mode, legged mode and transformable mode are carried out after briefly introducing the concept and control system design. Then, the obstacle climbing strategies under wheeled and legged modes are obtained. Finally, a prototype of the proposed robot is designed and manufactured based upon the simulation analysis. And the experiment results validate the effectiveness of the proposed transformable wheel-legged mobile robot. A new type of transformable wheel-legged mobile robot is proposed.The transformable mechanism integrates mobility and over-obstacle capability.The applicable condition of obstacle avoidance is given in detail.The experiment results validate the effectiveness of the proposed robot.

Comparison of Methods for Solving the Singular Configuration of a Wheel-Legged Mobile Robot

Comparison of Methods for Solving the Singular Configuration of a Wheel-Legged Mobile Robot

Functional Redesign of Mantis 2.0, a Hybrid Leg-Wheel Robot for Surveillance and Inspection

The paper discusses the redesign of the second version of the Mantis hybrid leg-wheel mobile robot, conceived for surveillance and inspection tasks in unstructured indoor and outdoor environments. This small-scale ground mobile robot is characterized by a main body equipped with two front actuated wheels, a passive rear axle and two rotating legs. Motion on flat and even ground is purely wheeled in order to obtain high speed, high energetic efficiency and stable camera vision; only in case of obstacles or ground irregularities the front legs realize a mixed leg-wheel locomotion to increase the robot climbing ability; in particular, the outer profile of the legs, inspired by the praying mantis, is specially designed to climb square steps. The multibody simulations and the experimental tests on the first prototype have shown the effectiveness of the mixed leg-wheel locomotion not only for step climbing, but also on uneven and yielding terrains. Nevertheless, extensive experimental tests have shown that the front wheels may slip in the last phase of step climbing in case of contact with some materials. In order to overcome this problem, the leg design has been modified with the introduction of auxiliary passive wheels, which reduce friction between legs and step upper surface; these wheels are connected to the legs by one-way bearings, in order to rotate only when they are pulled by the front wheels, and remaining locked when they have to push forward the robot. The influence of the auxiliary wheels on the front wheels slippage is investigated by means of theoretical analysis and multibody simulations.

Real-Time Motion Generation and Control Systems for High Wheel-Legged Robot Mobility

A wheel-legged mobile robot (WLMR) has both leg and wheel structures. WLMRs have adaptability advantages because they can change locomotion methods depending on the terrain. However, the location of a WLMR's center of gravity (CoG) is very high; thus, almost all existing WLMRs move statically. In this paper, whole body motion generation and various control systems are studied to facilitate higher WLMR mobility. To this end, a zero moment point (ZMP) is introduced as a stability index. In addition, WLMRs are modeled as single point mass linear inverted pendulums. Subsequently, online CoG pattern generation methods are proposed; one is a preview control approach, and a second is an approach that realizes the desired ZMP pattern using a zero-phase low-pass filter. It is then possible to generate the desired CoG patterns more easily and faster than with a preview control approach. The CoG patterns based on the single point model are constructed via the resolved-momentum-control approach. Finally, the effectiveness of the whole body motion pattern generated by the proposed methods is validated by simulations and experiments.

Feedforward Compensation Methods for Zero Moment Point Error from Gyrating Locomotion of Wheel-Legged Mobile Robot based on Previewing Centrifugal Force

Feedforward Compensation Methods for Zero Moment Point Error from Gyrating Locomotion of Wheel-Legged Mobile Robot based on Previewing Centrifugal Force

Dynamic Analysis of the Wheel-Legged Mobile Robot

The design of the wheel-legged mobile robot is mainly used for the early toxic gas leakage warning and disaster relief in the field of wild environment. The robot needs to cross some obstacles such as ditch and step when carrying out a task. The paper analyzes the strategies of robot passing the all kinds of obstacles. Considering the influence of disturbance by uneven road surface, the dynamic model of robot crossing the step and groove on the uneven road surface is built based on the robots structural features. While the control model of front wheel-leg is also presented based on the robot dynamic model. The results of simulation expriments demonstrate the correctness of the built dynamic model and laid the foundation for the design of the robot control system.

Research on Kinematic of the Wheel-Legged Robot Based on Uneven Road Surface

A new type of wheel-legged mobile robot is presented in the paper, which is mainly used for early toxic gas leakage warning and disaster relief in the field of wild environment. The paper first presents the structure feature of the new wheel-legged mobile robot. According to the structure of the robot, the kinematics model about robot moving on the smoothing-riding surface is built. On this basis, considering the effects of the disturbance by uneven road surface the paper carries out the robots kinematics analysis. To simulate the result of robot moving on the real road surface, the paper researches on the robots kenimatics by inputing some typical ground driving to the robot. The result of the simulation experiment shows that the robot pose error is more increasing. So the influence of ground disturbance to robot should be took into account in designing the control symstem, which can decrease the pose error and make robot move more accurately.

The Kinematic Analysis of the Walking Mechanism Based on the Leg-Wheel Mobile Robot

In the studying and designing process for the robotic walking system, a theoretical analysis and simulation on the kinematic characteristics of the walking mechanism of the robot is done. From our experiments, the characteristic curves of velocity and acceleration of the drop-foot point are obtained. The walking mechanism is stable in the translation cycle, which contributes to the stability of the robot motion, while the robot still can move at a certain speed. The stress of the walking mechanism is complicated in the step cycle, because both the velocity and acceleration get a certain amount of mutation.

Stability Control and Simulation of Wheel-Legged Mobile Robot in Mechanical Engineering

The wheel-legged mobile robot in a complex three-dimensional environment has strong through capacity .Study is very critical for the stability of the control of their body systems. In this paper , based on analysis of the structure of wheel-legged mobile robot designed, the stability is evaluated by the use of (Effective Mass Center) EMC , and the stability domain is established accordingly. A fuzzy adaptive PID control method is created , and verified by ADAMS and MATLAB co-simulation . Simulation results show that the robot in different terrestrial environment, can maintain good stability.

Development of a Hybrid Wheel-Legged Mobile Robot WR-3 Designed for the Behavior Analysis of Rats

This paper presents the design and development of a bio-inspired mobile robot called WR-3 (Waseda Rat no. 3). The purpose of the robot is to work as an experimental tool to study social interaction between rats and robots. According to the results of the analysis of the motion of rats, their behavior can be divided into two phases: movement and interaction. Therefore, a novel hybrid mechanism that uses wheels during the movement phase and legs while interacting has been designed to actuate WR-3. Consequently, the robot can move at a high speed using its wheels, and reproduce the rat's interaction behavior using its legs and other parts. Based on body structure of a mature rat, WR-3 has been designed with similar dimensions and shape as a mature rat, and the quality of the shape imitation has been verified by the experiments of a rat's interestingness to the robot and stuffed rat. Evaluation experiments show that WR-3 is capable of reproducing a rat's actions such as chasing, rearing, grooming, mounting, etc., similar to a real rat. Furthermore, preliminary social interaction tests with living rats reveal that WR-3 is to some extent able to evoke natural reactions form a real rat and is therefore able to perform a certain level of realistic interaction.

Dynamic Simulation-Based Action Planner for a Reconfigurable Hybrid Leg–Wheel Planetary Exploration Rover

In this paper, an action planning algorithm is presented for a reconfigurable hybrid leg–wheel mobile robot. Hybrid leg–wheel robots have recently receiving growing interest from the space community to explore planets, as they offer a solution to improve speed and mobility on uneven terrain. One critical issue connected with them is the study of an appropriate strategy to define when to use one over the other locomotion mode, depending on the soil properties and topology. Although this step is crucial to reach the full hybrid mechanism's potential, little attention has been devoted to this topic. Given an elevation map of the environment, we developed an action planner that selects the appropriate locomotion mode along an optimal path toward a point of scientific interest. This tool is helpful for the space mission team to decide the next move of the robot during the exploration. First, a candidate path is generated based on topology and specifications' criteria functions. Then, switching actions are defined along this path based on the robot's performance in each motion mode. Finally, the path is rated based on the energy profile evaluated using a dynamic simulator. The proposed approach is applied to a concept prototype of a reconfigurable hybrid wheel–leg robot for planetary exploration through extensive simulations and real experiments.