Sequential Motion Planning for Bipedal Somersault via Flywheel SLIP and Momentum Transmission with Task Space Control

In this paper, we present a sequential motion planning and control method for generating somersaults on bipedal robots. The somersault (backflip or frontflip) is considered as a coupling between an axile hopping motion and a rotational motion about the center of mass of the robot; these are encoded by a hopping Spring-loaded Inverted Pendulum (SLIP) model and the rotation of a Flywheel, respectively. We thus present the Flywheel SLIP model for generating the desired motion on the ground phase. In the flight phase, we present a momentum transmission method to adjust the orientation of the lower body based on the conservation of the centroidal momentum. The generated motion plans are realized on the full-dimensional robot via momentum-included task space control. Finally, the proposed method is implemented on a modified version of the bipedal robot Cassie in simulation wherein multiple somersault motions are generated

Design of high-performance legged robots: A case study on a hopping and balancing robot

The availability and capabilities of present-day technology suggest that legged robots should be able to physically outperform their biological counterparts. This thesis revolves around the philosophy that the observed opposite is caused by over-complexity in legged robot design, which is believed to substantially suppress design for high-performance. In this dissertation a design philosophy is elaborated with a focus on simple but high performance design. This philosophy is governed by various key points, including holistic design, technology-inspired design, machine and behaviour co-design and design at the performance envelope. This design philosophy also focuses on improving progress in robot design, which is inevitably complicated by the aspire for high performance. It includes an approach of iterative design by trial-and-error, which is believed to accelerate robot design through experience. This thesis mainly focuses on the case study of Skippy, a fully autonomous monopedal balancing and hopping robot. Skippy is maximally simple in having only two actuators, which is the minimum number of actuators required to control a robot in 3D. Despite its simplicity, it is challenged with a versatile set of high-performance activities, ranging from balancing to reaching record jump heights, to surviving crashes from several meters and getting up unaided after a crash, while being built from off-the-shelf technology. This thesis has contributed to the detailed mechanical design of Skippy and its optimisations that abide the design philosophy, and has resulted in a robust and realistic design that is able to reach a record jump height of 3.8m. Skippy is also an example of iterative design through trial-and-error, which has lead to the successful design and creation of the balancing-only precursor Tippy. High-performance balancing has been successfully demonstrated on Tippy, using a recently developed balancing algorithm that combines the objective of tracking a desired position command with balancing, as required for preparing hopping motions. This thesis has furthermore contributed to several ideas and theories on Skippy's road of completion, which are also useful for designing other high-performance robots. These contributions include (1) the introduction of an actuator design criterion to maximize the physical balance recovery of a simple balancing machine, (2) a generalization of the centre of percussion for placement of components that are sensitive to shock and (3) algebraic modelling of a non-linear high-gravimetric energy density compression spring with a regressive stress-strain profile. The activities performed and the results achieved have been proven to be valuable, however they have also delayed the actual creation of Skippy itself. A possible explanation for this happening is that Skippy's requirements and objectives were too ambitious, for which many complications were encountered in the decision-making progress of the iterative design strategy, involving trade-offs between exercising trial-and-error, elaborate simulation studies and the development of above-mentioned new theories. Nevertheless, from (1) the resulting realistic design of Skippy, (2) the successful creation and demonstrations of Tippy and (3) the contributed theories for high-performance robot design, it can be concluded that the adopted design philosophy has been generally successful. Through the case study design project of the hopping and balancing robot Skippy, it is shown that proper design for high physical performance (1) can indeed lead to a robot design that is capable of physically outperforming humans and animals and (2) is already very challenging for a robot that is intended to be very simple

生物の二関節間筋腱複合体を規範とした脚ロボットの開発

電気通信大学201

Analytical Center of Mass Trajectory Generation for Humanoid Walking and Running with Continuous Gait Transitions

We present an analytical trajectory generation framework for the combined computation of multiple walking and running sequences with continuous gait transitions. This framework builds on the Divergent Component of Motion (DCM)-based walking algorithm and the spline-based trajectory generation of the Biologically Inspired Deadbeat (BID) control for running. We describe our approach to generating closed-form center of mass (CoM) trajectories for walking and running by alternately linking the two gaits through continuity constraints. Thereby, we distinguish between vertical and horizontal planning. The vertical trajectory is computed in a forward recursion from the first to the last gait sequence. Due to the coupling of the gait sequences in the horizontal direction, we show the efficient generation of the horizontal CoM trajectory in a single matrix calculation. Subsequently, we unify the control strategies using a DCM tracking controller for the complete trajectory and integrate the proposed framework into an inverse dynamics-based whole-body controller. Finally, the presented approaches are validated in simulations with the humanoid robot Toro

DISEÑO Y PROTOTIPADO DE UN ROBOT MÓVIL AUTÓNOMO Y TELE-OPERADO (DESIGN AND PROTOTYPING OF AN AUTONOMOUS AND TELE-OPERATED MOBILE ROBOT)

Resumen En este artículo se presenta el diseño, modelado y prototipado de un robot móvil con aplicaciones potenciales en exploración de zonas accidentadas o de difícil acceso, reconocimiento, seguridad, defensa, rescate, entre otras. El sistema mecánico está basado en la configuración diferencial de robots móviles. El prototipo utiliza dos motores eléctricos de alta potencia que le permiten sortear obstáculos y navegar en terrenos difíciles con buena precisión y a una velocidad máxima de 20 km/h. El sistema de control está basado en un sistema embebido y dos sensores principales: una cámara RGB y un arreglo de sensores ultrasónicos que habilitan la navegación autónoma. Adicionalmente el robot propuesto puede ser tele-operado utilizando un casco de realidad virtual y un dispositivo háptico kinestésico mientras que la transmisión de video y el intercambio de datos se realizan por un módulo de comunicación de radiofrecuencia (RF). Palabras Clave: Navegación autónoma, robot móvil, sensado ultrasónico, tele-operación, vehículo diferencial, visión por computadora. Abstract This paper presents the design, modeling, and prototyping of a mobile robot with potential applications in the fields of exploration, reconnaissance, security, defense, rescue, among others. The mechanical system is based on the differential drive structure driven by two high-power electrical motors that allow the prototype to negotiate obstacles and navigate rough terrain with a high degree of accuracy at a maximum speed of 20 km/h. The control system is based on an embedded micro-controller architecture and two main sensors: a color camera and an array of ultrasonic sensors, which enable autonomous navigation of the robot. In addition, the robot can also be tele-operated using a virtual reality helmet and a kinesthetic haptic device while video and data exchange are provided by a RF communication link. Keywords: Autonomous navigation, differential vehicle, machine vision, mobile robot, tele-operation, ultrasonic sensing