Soft Steps: Exploring Quadrupedal Locomotion With Modular Soft Robots (original) (raw)
Related papers
IEEE Robotics and Automation Letters, 2019
Like their natural mammalian and reptilian counterparts, legged soft robots require robust walking dynamics and untethered functionality in order to swiftly maneuver through unstructured environments. Progress in this domain requires careful selection of soft limb actuators and integration of power and control electronics into a soft robotics platform capable of biologically-relevant locomotion speeds without dependency on external hardware. We demonstrate this with an untethered soft palm-sized, 25g soft electrically actuated quadruped (SEAQ; Fig. 1(a)) that is capable of crawling at a maximum speed of 0.56 body length per second (3.2cm/s) and making 90 degree turns in two complete gait cycles (~5s). The robot is composed of a flexible printed circuit board and electrically-powered soft limbs that contain shape memory alloy (SMA) wires inserted between pre-stretched layers of a soft, thermally-conductive elastomer. Its versatile mobility and robust dynamics are demonstrated by its ability to walk on a variety of surfaces-including inclines, rocky and granular surfaces, and steps that are over half the robot height-and maintain continuous forward locomotion through confined space or after being dropped from an elevated height. In addition to these locomotion studies, we perform an experimental study on the blocking force of a single actuator to provide independent support for the feasibility of untethered soft robot walking with SMA-based actuation.
Study on Soft Robotic Pinniped Locomotion
2023 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)
Legged locomotion is a highly promising but under-researched subfield within the field of soft robotics. The compliant limbs of soft-limbed robots offer numerous benefits, including the ability to regulate impacts, tolerate falls, and navigate through tight spaces. These robots have the potential to be used for various applications, such as search and rescue, inspection, surveillance, and more. The state-ofthe-art still faces many challenges, including limited degrees of freedom, a lack of diversity in gait trajectories, insufficient limb dexterity, and limited payload capabilities. To address these challenges, we develop a modular soft-limbed robot that can mimic the locomotion of pinnipeds. By using a modular design approach, we aim to create a robot that has improved degrees of freedom, gait trajectory diversity, limb dexterity, and payload capabilities. We derive a complete floating-base kinematic model of the proposed robot and use it to generate and experimentally validate a variety of locomotion gaits. Results show that the proposed robot is capable of replicating these gaits effectively. We compare the locomotion trajectories under different gait parameters against our modeling results to demonstrate the validity of our proposed gait models.
Planning Natural Locomotion for Articulated Soft Quadrupeds
2022 International Conference on Robotics and Automation (ICRA)
Embedding elastic elements into legged robots through mechanical design enables highly efficient oscillating patterns that resemble natural gaits. However, current trajectory planning techniques miss the opportunity of taking advantage of these natural motions. This work proposes a locomotion planning method that aims to unify traditional trajectory generation with modal oscillations. Our method utilizes task-space linearized modes for generating center of mass trajectories on the sagittal plane. We then use nonlinear optimization to find the gait timings that match these trajectories within the Divergent Component of Motion planning framework. This way, we can robustly translate the modesaware centroidal motions into joint coordinates. We validate our approach with promising results and insights through experiments on a compliant quadrupedal robot.
Design, Fabrication, and Locomotion Analysis of an Untethered Miniature Soft Quadruped, SQuad
IEEE Robotics and Automation Letters, 2020
The conventional robotics, which involves utilization of robots made out of hard materials like metals and hard plastics, has helped humankind automate many different sorts of labor and such robots have been assisting the humans in various tasks. Nevertheless, some applications require very delicate interactions and adaptability of the robots to unstructured elements and obstacles; which can only be provided by softness. The miniature and untethered robot in this work is fully made out of soft structural materials and uses a flexible circuit board. Only the electronic components, actuators and several little connection parts are hard. Its soft legs, body, and circuit enables it to overcome obstacles that conventional hard miniature robots tend to be stopped by. For the soft robot presented, walking and obstacle climbing experiments were done and pitch angle, roll angle, robot's centroid position and stiffness analyses were conducted. Additionally, three other robots are fabricated in hard body-hard leg, hard body-soft leg, and soft body-hard leg configurations and the effects of body and leg compliance on the locomotion performance are investigated. The results show that a soft body-soft leg robot configuration can scale an obstacle 1.44 times its body height whereas the hard bodied and hard legged robot can only go over 0.88 times its body height. The results also indicate that the softness of the body effects the scalable obstacle height more than the softness of the legs at this length scale.
Design, Simulation, Fabrication and Planning of Bio- Inspired Quadruped Robot [May 2014]
This work reports design, simulation, fabrication, and planning of bio-inspired quadruped robot. This dissertation deals with two types of bio-inspired quadruped locomotion patterns, namely, mammalian and reptilian. Legged locomotion is one of the most successful locomotion patterns found in the nature. Quadruped walking in many mammals and reptiles have made them very successful in surviving against tough environments such as uneven terrains. Nature evolved legged locomotion over half a billion years. It should be noted that the biological evolution favoured legged locomotion instead of wheeled locomotion in spite of wheeled locomotion being fast. This is because more than half of Earth’s landmass has highly rough terrain and can be traversed by legged rather than wheeled locomotion. We thus take inspiration from the nature to develop legged robots that can traverse on rough terrains and has advantage over wheeled robots. We developed alligator-inspired robot at the Mechatronics la...
Starleth: A compliant quadrupedal robot for fast, efficient, and versatile locomotion
2012
This paper introduces StarlETH, a compliant quadrupedal robot that is designed to study fast, efficient, and versatile locomotion. The platform is fully actuated with high compliant series elastic actuation, making the system torque controllable and at the same time well suited for highly dynamic maneuvers. We additionally emphasize key elements of a powerful real time control and simulation environment. The work is concluded with a number of experiments that demonstrate the performance of the presented hardware and controllers.
Teleoperation of Soft Modular Robots: Study on Real-time Stability and Gait Control
Soft robotics holds tremendous potential for various applications, especially in unstructured environments such as search and rescue operations. However, the lack of autonomy and teleoperability, limited capabilities, absence of gait diversity and real-time control, and onboard sensors to sense the surroundings are some of the common issues with soft-limbed robots. To overcome these limitations, we propose a spatially symmetric, topologically-stable, soft-limbed tetrahedral robot that can perform multiple locomotion gaits. We introduce a kinematic model, derive locomotion trajectories for different gaits, and design a teleoperation mechanism to enable realtime human-robot collaboration. We use the kinematic model to map teleoperation inputs and ensure smooth transitions between gaits. Additionally, we leverage the passive compliance and natural stability of the robot for toppling and obstacle navigation. Through experimental tests, we demonstrate the robot's ability to tackle various locomotion challenges, adapt to different situations, and navigate obstructed environments via teleoperation.
Based on the analogy of biological and mechatronical locomotion systems a general abstract modular structure is presented that is capable to model biological and technical quadrupedal locomotion systems. The basic structural elements used for the different kinds of subsystems are described in their function and interaction. The methodology is applied to the four legged walking machine BISAM to retrieve a dynamic system model controlled by the existing behavior based motion controller. As a contribution to the improvement of the foot positioning a model based motor controller has been formulated using the inherent knowledge of the dynamic system model.
Generating gaits for physical quadruped robots
Proceedings of the 13th annual conference companion on Genetic and evolutionary computation - GECCO '11, 2011
Creating gaits for legged robots is an important task to enable robots to access rugged terrain, yet designing such gaits by hand is a challenging and time-consuming process. In this paper we investigate various algorithms for automating the creation of quadruped gaits. Because many robots do not have accurate simulators, we test gait-learning algorithms entirely on a physical robot. We compare the performance of two classes of gait-learning algorithms: locally searching parameterized motion models and evolving artificial neural networks with the HyperNEAT generative encoding. Specifically, we test six different parameterized learning strategies: uniform and Gaussian random hill climbing, policy gradient reinforcement learning, Nelder-Mead simplex, a random baseline, and a new method that builds a model of the fitness landscape with linear regression to guide further exploration. While all parameter search methods outperform a manually-designed gait, only the linear regression and Nelder-Mead simplex strategies outperform a random baseline strategy. Gaits evolved with HyperNEAT perform considerably better than all parameterized local search methods and produce gaits nearly 9 times faster than a hand-designed gait. The best HyperNEAT gaits exhibit complex motion patterns that contain multiple frequencies, yet are regular in that the leg movements are coordinated.
Development of a Biomimetic Quadruped Robot
Journal of Bionic Engineering, 2007
This paper presents the design and prototype of a small quadruped robot whose walking motion is realized by two piezocomposite actuators. In the design, biomimetic ideas are employed to obtain the agility of motions and sustainability of a heavy load. The design of the robot legs is inspired by the leg configuration of insects, two joints (hip and knee) of the leg enable two basic motions, lifting and stepping. The robot frame is designed to have a slope relative to the horizontal plane, which makes the robot move forward. In addition, the bounding locomotion of quadruped animals is implemented in the robot. Experiments show that the robot can carry an additional load of about 100 g and run with a fairly high velocity. The quadruped prototype can be an important step towards the goal of building an autonomous mobile robot actuated by piezocomposite actuators.