Skin deformation haptic devices worn on the finger pad provide realistic touch feedback during interactions with virtual objects. Two primary challenges in creating such devices are: first, making a multidegree-of-freedom device (DoF) that is small and lightweight so it does not encumber the wearer and second, providing accurate control of forces displayed to the finger pad. This work presents a 4-DoF finger pad haptic device, called Fourigami, that addresses these challenges. We address the first challenge using origami manufacturing methods and pneumatic actuation to fabricate a 25 g prototype that displays normal, shear, and twist and can be easily worn on the finger pad. We address the second challenge using a low-profile, 6-DoF, force/torque sensor to control forces displayed to the finger. Fourigami has a bandwidth ranging from 2 to 4 Hz depending on direction, and when acting on a human finger, it exerts forces ranging from$\pm$1.0 N in shear, 4.2 N in normal, and$\pm$4.2 N$\cdot$mm of twist. Finally, we demonstrate the device’s efficacy when rendering haptic feedback to a user tracking a sinusoidal trajectory and a trajectory representing interactions with a virtual object.

Robotic origami design allows creating meso-scale robotic systems and mechanisms not limited by degrees of freedom, miniaturization and assembly downsides of conventional transmission mechanisms. However, unlike the traditional rigid approaches, robotic origami application has been limited by the complex deformation and kinematics of the compliant joints and actuation based on active materials or conventional electric motors. To generalize their application at meso-scale requires a combination of the predictability of traditional rigid kinematics and the manufacturing flexibility of robotic origami. Here we present a study of conventional transmission mechanisms, including a slider-crank and cam-follower, made in quasi-2D form by selective machining and stacking of multiple layers of composite material with minimal assembly. Owing to a compliant design powered by low-profile piezoelectric motors, our 5.3 mm thick and lightweight mechanisms transmit rotational motion to translational movements in and out-of-plane. We develop analytic models that we validate in terms of force and motion output on our prototypes.

Robotic origami allows rapid prototyping of intelligent robots and machines constructed from thin sheets of functional materials. Multimaterial-based design freedom of origami robots creates functional versatility; however, the design parameters pose challenges in their mechanical layout and fabrication. While the conventional robot design follows a coherent and well-established design process, the construction of origami robots requires close study of their three-dimensional (3-D) and two-dimensional (2-D) geometries, compliant mechanisms, functional material specific components, and 2-D fabrication methods. In this paper, we report a systematic design methodology for building origami-inspired machines and robots based on these four essential design features. We provide their comprehensive formulation, comparing them to conventional robots and highlighting design challenges as well as potentials. We demonstrate the applicability of our procedure to the majority of origami robots in the literature and also validate it by designing a centimeter-scale jumping and crawling origami robot, Tribot, as a showcase. The 6-g Tribot crawls with fixed steps in a closed loop, adjusts its vertical jumping height by power modulation, and overcomes obstacles of 45-mm height by side jumps. This paper advances the design and fabrication methodology of origami robots, with customizable functionality from the ground-up.

There are several challenges in down-sizing robots for transportation deployment, diversification of locomotion capabilities tuned for various terrains, and rapid and on-demand manufacturing. In this paper we propose an origami-inspired method of addressing these key issues by designing and manufacturing a foldable, deployable, and self-righting version of the origami robot Tribot. Our latest Tribot prototype can jump as high as 215 mm, five times its height, and roll consecutively on any of its edges with an average step size of 55 mm. The 4 g robot self-deploys nine times of its size when released. A compliant roll cage ensures that the robot self-rights onto two legs after jumping or being deployed and also protects the robot from impacts. A description of our prototype and its design, locomotion modes, and fabrication is followed by demonstrations of its key features.

Origami robots (Robogamis) use architecture to strategically activate different sets and sequence of actuators to achieve large variety of reconfigurable forms. Tribot is a unique mobile origami robot that can simultaneously choose between two modes of locomotion: jumping and crawling. When assembled, Tribot measures 64 × 34 × 20 mm3, weighs 4 g, crawls at 17% of its body length per gait cycle and jumps seven times its height repeatedly without needing to be reset. To optimize the practicality of the nominally 2D design, we made two different approaches to build the prototypes. For one of them, we used the “traditional”, monolithic, layer-by-layer robogami fabrication method and the second, we printed out most parts using a multi-material 3D printer. By showing the performance of two prototypes side-by-side, we show that with the 3D printer, we can minimize the number of functional layers and reduce the fabrication time. The embedded sensors allow Tribot's crawling gait pattern and jumping height to be modulated with a closed loop control. We compare the expected gait step size and displacement to that of the presented prototype while describing the design and control parameters to achieve the experimental results. We also illustrated the preliminary graphical design tool platform developed to optimize the next design iteration of Tribot.

This work focuses on the design of driver for PiezoLegs actuator used for high precision positioning purposes. Motor is driven with the set of periodical voltages with known frequency, amplitude and phase shift between the phases. Motor's operation has been investigated in detail and clear relationships between the amplitude and phase shifts between the phases and motor step size have been established. According to the motor analysis, set of design requirements for the design of driver is given. Particular solution meeting these requirements and satisfying the given design constraints is presented. Driver is experimentally evaluated for power consumption and analyzed in frequency domain, it's performance is compared to the performance of a commercially available driver for the same motor. Designed driver shows improved performance.

This article presents a kinematic model and control of a galvanometric laser beam steering system for high precision marking, welding or soldering applications as a microfactory module. Galvo systems are capable of scanning laser beam with relatively high frequencies that makes them suitable for fast processing applications. For the sake of flexibility and ease of use 2D reference shapes to be processed are provided as CAD drawings. Drawings are parsed and interpolated to x - y reference data points on MATLAB then stored as arrays in C code. C header file is further included as reference data points to be used by the system. Theoretical kinematic model of the system is derived and model parameters are tuned for practical implementation and validated with respect to measured positions on rotation space with optical position sensor and image field with position sensitive device. Machining with material removal requires high power laser to be employed that makes position measurement on image field unfeasible. Therefore for closed loop applications optical position sensor embedded in galvo motors is used for position feedback. Since the model approved to be approximately linear in the range of interest by simulations, a PI controller is used for precise positioning of the galvo motors. Experimental results for tracking circular and rectangular shape references are proved to be precise with errors of less than 2%.

This work presents functional description of a walking piezoelectric motor and its control in nanometer precision. For this purpose a dynamical model of the actuator is derived based on simple mass spring damper system. Model parameters are estimated from step response plot and the system is expressed with second order transfer function. Additional identification experiments verified the theoretical kinematics of the bimorph legs. These experiments demonstrate approximately linear relation between the legs displacement in x and y directions to the applied voltages. Based on derived system model and identification results a PI controller followed by Hadamard transformation is proposed as a controller scheme. Experimental results for staircase and sinusoidal references reveal precise positioning capabilities of the system with the proposed control scheme down to few nanometers.