Lateral Stability of a Mobile Robot Utilizing an Active Adjustable Suspension

Abstract

Mobile robots are expected to traverse on unstructured terrain, especially uneven terrain, or to climb obstacles or slopes. This paper analyzes one such passively–actively transformable mobile robot that is principally aimed at the above issue. A passive locomotion traverses on a rough and flat terrain; an active reconfiguration with an active suspension. This paper investigates the lateral stability of this mobile robot when it reconfigures itself to adjust its roll angle with the active suspension. The principles and configurations of the robot and its active suspension are presented. To analyze the effects of the suspensions’ inputs on robot stability, a mathematic model of the robot on side slopes is presented. Based on the evaluation method of the stability pyramid theory, an analytical expression representing the relationship between the input of the active suspension (linear actuator length) and stability evaluation index on transverse slopes is obtained. The results show that there is an increase in both the lateral stability and minimum lateral tip-over angle under different ground clearances when adjusting the active inputs. Furthermore, the models presented here provide theoretical references and optimization directions for the design and control of mobile robots with adjustable suspensions.

On the Suspension Design of Paquitop, a Novel Service Robot for Home Assistance Applications

“…Therefore, a non-axisymmetric footprint is preferable to a symmetric one so tha robot is able to offer, when needed, a reduced profile to pass through confined spac is worth noticing that the presence of four contact points with the ground implies the n of using an adequate suspension system, necessary to assess the soil unevenness an enhance its capability to overpass reasonably low obstacles without compromisin whole balance. In fact, most indoor robots do not make use of suspensions, while out rovers provided with suspensions often adopt active systems [19,20]. To contain costs complexity of the project, a passive suspension approach is preferable.…”

“…Figure 10 reports the test results for Case study 2. About the vertical motion of the platform, it is evident that, due to the presence of the kinematic constraint (20), the one-arm configuration does not filter enough the vertical disturbance introduced by the step. For this reason, the architectures 2A and 2AR show better behaviour at overpassing obstacles, with a maximum vertical displacement from the static equilibrium condition 80.74% and 82.56% lower, respectively, than the variation evaluated for design 1A.…”

Multi-terrain Quadrupedal-wheeled Robot Mechanism: Design, Modeling, and Analysis

“…This paper builds upon the concepts in the abovementioned pieces of literature from an engineering standpoint. For active suspension, we have developed a design similar to that of [5], [4], [9]. To improve on these, we incorporated servomotors in our suspension system.…”

“…To improve on these, we incorporated servomotors in our suspension system. Unlike that of Jiang et al [9], which is a linear-motor actuated rocker-and-balance mechanism, ours is an electronically controlled servomechanism that has higher precision in the control of the pitch and roll motion of the robot, during navigation. For steering, we drew insights from [3], [8], to formulate a skid-steering control model for our robot.…”

Trajectory Optimization for Hybrid Wheeled-Legged Robots in Challenging Terrain

“…Other active articulated wheeled robots that employ kinematic reconfigurability methods for traversing uneven terrain can be found in (Wettergreen et al, 2010;Freitas et al, 2010;Inotsume et al, 2013;Jiang et al, 2019). On the other hand, the wheeled-legged robots presented in (Suzumura and Fujimoto, 2012;Giftthaler et al,2017;Giordano et al, 2009) use a kinematic-based control algorithm to generate velocity commands for the wheels, but they only present results for flat terrain navigation and do not consider the terrain in the planning algorithm.…”