![A mechanical design sketch of the single actuator differentailly driven robot used in [7].](https://www.researchgate.net/profile/Mohamad-Alsalman/publication/281836118/figure/fig1/AS:613444780847111@1523268041247/A-mechanical-design-sketch-of-the-single-actuator-differentailly-driven-robot-used-in-7_Q320.jpg)
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Modeling, Analysis, and Controllability of a Single-Actuator Differentially-Driven Robot
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In this paper, we develop an elaborate three-dimensional dynamical model for a novel single-actuator variable-diameter differentially-driven robot by taking recourse to Lagrangian formulation. Utilizing this model, we were able to analyze the various parameters and develop design tools that could be used in realizing such a robot with certain motion requirements. Given the single actuator design that inherently limits steering, the proposed model is an excellent platform to test optimal path planning techniques such as Dubins curves. We study the effect of dynamical forces on following time-optimal trajectories and finally we analyze the controllability of our system.
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... His design, seen in Fig.1, includes flexible wheels that are passively actuated by transferring the mass concentration of the system along the wheel axis. Alsalman et al. [5] altered Sfeir's design by replacing the pendulum with a rotating disk, and modeled the system for motion over flat terrain, taking into account the dynamics involved in the disk actuation and the effects of the parameters of the system on the flexible design of the wheels. This paper expands on that work by looking into rough terrain mobility and the constraints involved in the process. ...
In this paper, a three dimensional model for a variable-diameter wheeled mobile base is introduced which is tailored for modeling locomotion on rough terrain. The motion planning of the introduced model is novel, since the forward motion of the robot is governed by a central rolling disk, while its steering is governed by the lateral shifting of the disk, thus yielding relatively complex equations of motion. To simplify the numerical simulations, new constraint stabilization techniques are developed to transform the Differential Algebraic Equations (DAE) of motion to ordinary differential equations (ODE). Using the developed model, several locomotion simulations are performed to traverse optimal planar trajectories as well as to mitigate bumps or disturbances in the terrain.
The purpose of this study is to implement a trajectory-tracking control system with attitude compensation for a new 1-DOF-driven robot called Lizard-Inspired Single-Actuated Robot (LISA). Previous studies have proposed various morphologies for 1-DOF robots, which present certain challenges. LISA, a multi-legged robot capable of propulsion and turning within a single DOF, overcomes these challenges. In this study, we formulate the kinematics of LISA, considering turning angle, stride length, posture, and turning radius. A unique robot coordinate is defined to derive the kinematics, enabling a symmetric representation of crucial state quantities such as turning angles and link angles. Subsequently, we design the trajectory-tracking control system with attitude compensation, comprising feed forward control, PD control, and attitude compensation control. This control system exhibits the characteristic that, when LISA has a significant attitude error relative to the reference trajectory, the attitude compensator corrects LISA's orientation, while PD control is employed for smaller errors to control LISA's trajectory. This characteristic is achieved by tuning the output ratio of the PD control input to the attitude compensation input. The effectiveness of the designed control system is initially validated through numerical simulations, employing linear and circular trajectories for verification. We also demonstrate that the control system proposed in this paper has a broader stabilization region compared to the conventional LISA control system. Finally, we verify the effectiveness of the designed control system through implementation experiments, confirming its efficacy as a trajectory-following control system for LISA.
In this study, trajectory-tracking control for a lizard-inspired single-actuated robot (LISA) is implemented using a novel morphology. A high degree of reproducibility is obtained between the results of kinematic analysis and the behavior of the actual robot. Several 1-degree-of-freedom (DOF)-driven robots have been proposed. However, the application of these robots is severely restricted because of their inherent morphology limitations. LISA is a multilegged robot that can overcome these disadvantages and propel and turn with 1-DOF. In this study, we formulate the kinematics, such as the turning angle and stride length, of LISA. Furthermore, a unique robot coordinate is defined to enable the symmetrical representation of critical robot state quantities. Next, a trajectory-tracking control system based on the proportional-integral-derivative (PID) control is designed, and it is verified by both experiments and numerical simulations. Finally, the results of the experiments and numerical simulations are quantitatively compared according to the root mean square, and the reproducibility of the kinematics analysis and the behavior of the actual system are discussed. This study makes the following contributions: (1) The morphology of LISA facilitates analytical results with only kinematic analysis, which is considerably simpler than dynamics analysis. (2) LISA achieved sufficiently good kinematic performance for the required motions. Experiments revealed that the designed trajectory-tracking control system allows for LISA to appropriately track several types of trajectories.
A novel high adaptability out-door mobile robot with diameter-variable wheels was proposed in this paper. The robot has advantages of good climbing obstacle capability, high terrain adaptability and stability for the self-adapting suspension and walking wheel combining the efficiency of wheels with the climbing mobility of legs. The mechanism structure and working principle were described. The kinematics model and dynamic model are presented of the folding and unfolding of the wheel and interaction between wheel and terrain respectively. A simulation in MSC.ADAMS has been carried out to verify the operation and the reality of the prototype. The simulation results show that the robot with diameter-variable wheels has good performance of climbing obstacles in the rough terrain.
In this paper, we introduce a concept design for a single-actuator differentially driven robot. The design is based on connecting two variable-diameter wheels to the same drive shaft. The wheels are designed to have engineered stiffness so that the diameters of the wheels are varied by shifting the weight of the drive mechanism from side to side. We also develop the kinostatic and dynamic models of the mobile platform, which is used later to perform motion planning techniques.
In this paper, we present a deformable wheel robot using the ball-shaped waterbomb origami pattern, so-called magic-ball pattern. The magic-ball origami pattern is a well-known pattern that changes its shape from a long cylindrical tube to a flat circular tube. By using this special structure, a wheel with mechanical functionalities can be achieved without using many mechanical parts. Moreover, because of the characteristic that the structure constrains its own movement, it is possible to control the whole shape of the wheel using only few actuators. And also, from analysis of the wheel structure in kinematic model, the performance of the wheel and determine the condition for actuators can be predicted. We think that the proposed design for the deformable wheel shows the possibility of using origami structure as a functional structure with its own mechanism.
IMPASS (Intelligent Mobility Platform with Active Spoke System) is a novel locomotion system concept that utili zes rimless wheels with individually actuated spokes to provide the ability to step over large obstacles like legs, adapt to uneven surfaces like tracks, yet retaining the speed and simplicity of wheels. Since it lacks the complexity of legs and has a large effective (wheel) diameter, this highly adaptive system can move over extreme terrain with ease while maintaining respectable travel speeds. This paper presents the concept, preliminary kinematic analyses and design of an IMPASS based robot with two actuated spoke wheels and an articulated tail. The actuated spoke wheel concept allows multiple modes of motion, which give it the ability to assume a stable stance using three contact points per wheel, walk with static stability with two contact points per wheel, or stride quickly using one contact point per wheel. Straight-line motion and considerations for turning are discussed for the one-and two-point contact schemes followed by the preliminary design and recommendations for future study.