Ryuma Niiyama

Athlete Robot with applied human muscle activation patterns for bipedal running

The essential component of legged locomotion is control of the ground reaction force. To understand the role of the musculoskeletal body in dynamic locomotion, we investigate bipedal running using a musculoskeletal “Athlete Robot”. The configuration of the muscles in the robot is compatible with the human. The spring-like property of the human lower leg during running is modeled as an elastic blade foot based on findings from biomechanics. The motor command of the robot is represented by time series data of muscle activation. The muscle activation patterns are determined from numerical calculation using a model of the musculoskeletal leg based on the measurement of muscle activity and kinetic data of the human movements. In the simulation results, the robot runs 8 steps with a speed of 3 m/s. We also demonstrate that the real bipedal robot is able to run for several steps.

jamSheets: thin interfaces with tunable stiffness enabled by layer jamming

This works introduces layer jamming as an enabling technology for designing deformable, stiffness-tunable, thin sheet interfaces. Interfaces that exhibit tunable stiffness properties can yield dynamic haptic feedback and shape deformation capabilities. In comparison to the particle jamming, layer jamming allows for constructing thin and lightweight form factors of an interface. We propose five layer structure designs and an approach which composites multiple materials to control the deformability of the interfaces. We also present methods to embed different types of sensing and pneumatic actuation layers on the layer-jamming unit. Through three application prototypes we demonstrate the benefits of using layer jamming in interface design. Finally, we provide a survey of materials that have proven successful for layer jamming.

Biomechanical Approach to Open-Loop Bipedal Running with a Musculoskeletal Athlete Robot

In this study, a musculoskeletal robot is used as a tool to investigate how animals control their complex body. Sprinting is a challenging task that requires maximizing the potential resources of a musculoskeletal structure. Our approach to robotic sprinting is the Athlete Robot — a musculoskeletal robot with elastic blade feet controlled by feedforward motor command. We use a catapult launcher to provide a stable start to a sprint, and then examine the relation between the initial velocity imparted by the launcher and the change in orientation of the robot. We also investigate the influence of the change in elasticity of the blade foot. The results show that acceleration causes anterior inclination after the first step. The elasticity of the foot dominates the duration of the support phase. The musculoskeletal system of the Athlete Robot is modified to suit catapulted running. Based on the results from real robot experiments, we can provide a consistent propelling force using the catapult launcher. We demonstrate the Athlete Robot running for five steps after a catapult launch, using only feedforward command.

Design principle based on maximum output force profile for a musculoskeletal robot

Purpose – The purpose of this paper is to focus on an engineering application of the vertebrate musculoskeletal system. The musculoskeletal system has unique mechanisms such as bi‐articular muscle, antagonistic muscle pairs and muscle‐tendon elasticity. The “artificial musculoskeletal system” is achieved through the use of the pneumatic artificial muscles. The study provides a novel method to describe the force property of the articulated mechanism driven by muscle actuator and a transmission.Design/methodology/approach – A musculoskeletal system consists of multiple bodies connected together with rotational joints and driven by mono‐ and bi‐articular actuators. The paper analyzes properties of the musculoskeletal system with statically calculated omni‐directional output forces. A set of experiments has been performed to demonstrate the physical ability of the musculoskeletal robot.Findings – A method to design a musculoskeletal system is proposed based on an analysis of the profile of convex polygon of m...

Sticky Actuator: Free-Form Planar Actuators for Animated Objects

We propose soft planar actuators enhanced by free-form fabrication that are suitable for making everyday objects move. The actuator consists of one or more inflatable pouches with an adhesive back. We have developed a machine for the fabrication of free-from pouches; squares, circles and ribbons are all possible. The deformation of the pouches can provide linear, rotational, and more complicated motion corresponding to the pouchs geometry. We also provide a both manual and programmable control system. In a user study, we organized a hands-on workshop of actuated origami for children. The results show that the combination of the actuator and classic materials can enhance rapid prototyping of animated objects.

Pouch Motors: Printable/inflatable soft actuators for robotics

We propose a new family of fluidic soft actuators called Pouch Motors. The pouch motors are developed to create printable actuators for enhancing mass-fabrication of robots from sheet materials using easily accessible tools. The pouch motor consists of one or more gas-tight bladders (called pouches) fabricated by heat bonding. We developed two types of actuators from inflatable pouches: the linear pouch motor and the rotational pouch motor. Our theoretical analysis predicts the static force-length and moment-angle relationships of these actuators under pressure control. We compare the theoretical bounds with actual results achieved using several fabricated devices. We developed a fabrication process of pouch motors using a heat stamping technique that allows mass-manufacturing. We also demonstrate three robot bodies with embedded pouch motors: a parallel gripper, a robotic arm with antagonistic actuation, and legged walking robot with a self-contained miniature pneumatic system.

Neural-body coupling for emergent locomotion: A musculoskeletal quadruped robot with spinobulbar model

To gain a synthetic understanding of how the body and nervous system co-create animal locomotion, we propose an investigation into a quadruped musculoskeletal robot with biologically realistic morphology and a nervous system. The muscle configuration and sensory feedback of our robot are compatible with the mono- and bi-articular muscles of a quadruped animal and with its muscle spindles and Golgi tendon organs. The nervous system is designed with a biologically plausible model of the spinobulbar system with no pre-defined gait patterns such that mutual entrainment is dynamically created by exploiting the physics of the body. In computer simulations, we found that designing the body and the nervous system of the robot with the characteristics of biological systems increases information regularities in sensorimotor flows by generating complex and coordinated motor patterns. Furthermore, we found similar results in robot experiments with the generation of various coordinated locomotion patterns created in a self-organized manner. Our results demonstrate that the dynamical interaction between the physics of the body with the neural dynamics can shape behavioral patterns for adaptive locomotion in an autonomous fashion.

Weight and volume changing device with liquid metal transfer

This paper presents a weight-changing device based on the transfer of mass. We chose liquid metal (Ga-In-Tin eutectic) and a bi-directional pump to control the mass that is injected into or removed from a target object. The liquid metal has a density of 6.44g/cm3, which is about six times heavier than water, and is thus suitable for effective mass transfer. We also combine the device with a dynamic volume-changing function to achieve programmable mass and volume at the same time. We explore three potential applications enabled by weight-changing devices: density simulation of different materials, miniature representation of planets with scaled size and mass, and motion control by changing gravity force. This technique opens up a new design space in human-computer interactions.

Self-folding and self-actuating robots: A pneumatic approach

Self-assembling robots can be transported and deployed inexpensively and autonomously in remote and dangerous environments. In this paper, we introduce a novel self-assembling method with a planar pneumatic system. Inflation of pouches translate into shape changes, turning a sheet of composite material into a complex robotic structure. This new method enables a flat origami-based robotic structure to self-fold to desired angles with pressure control. It allows a static joint to become dynamic, self-actuate to reconfigure itself after initial folding. Finally, the folded robot can unfold itself at the end of a robotic application. We believe this new pneumatic approach provides an important toolkit to build more powerful and capable self-assembling robots.

A musculoskeletal bipedal robot designed with angle-dependent moment arm for dynamic motion from multiple states

When robots make smooth transitions in dynamic motions, they must exert large force over widely various postures. To expand the range of postures that robots can take during dynamic motions, we propose that robots be designed with an Angle-Dependent Moment Arm (ADMA) with biased pivot, for which torque characteristics of actuators attached to joints are adjustable. From jumping simulations of robotic legs designed with ADMA, we demonstrate that ADMA improves robustness to postural and motion timing changes by shifts of the optimal posture, which are also observed in jumping experiments using a full-sized, bipedal robot. Graphical Abstract