Force Capabilities of Two-Degree-of-Freedom Serial Robots Equipped With Passive Isotropic Force Limiters

This paper proposes the use of passive force and torque limiting devices to bound the maximum forces that can be applied at the end-effector or along the links of a robot, thereby ensuring the safety of human-robot interaction. Planar isotropic force limiting modules are proposed and used to analyze the force capabilities of a two-degree-of-freedom planar serial robot. The force capabilities at the end-effector are first analyzed. It is shown that, using isotropic force limiting modules, the performance to safety index remains excellent for all configurations of the robot. The maximum contact forces along the links of the robot are then analyzed. Force and torque limiters are distributed along the structure of the robot in order to ensure that the forces applied at any point of contact along the links are bounded. A power analysis is then presented in order to support the results. Finally, examples of mechanical designs of force/torque limiters are shown to illustrate a possible practical implementation of the concept.

Development of Manufacturing Method for Truss Core Panel Based on Origami-Forming

Although honeycomb panel is widely used in various stages, its adhesive for gluing honeycomb core and plate may burn by fire, leading to the requirement of another lightweight and high stiffness panel. Recently, an Origami structure called Truss Core Panel (TCP) is known as a lightweight structure that has equivalent bending stiffness as honeycomb panel, and safer in fire. However, some difficulties are found in forming TCP in general. In this study, a new forming process of TCP based on origami-forming is developed. In particular, the TCP is partitioned into several parts that are flat unfoldable into 2D crease patterns. After that, blanks of material are cut as the shapes of those crease pattern, and be formed by a robot system to get the desired 3D shape. Firstly, partition method by dividing TCP into pyramid cores and sheet plate is presented, suggesting an ability to manufacture a wider range of structure than before. Tools arrangement of robot device and a countermeasure for springback are considered. Next, by applying Origami unfolding technique, an improvement of partition method is proposed: dividing TCP into cores rows, and then searching for a Origami crease pattern in order to fold that cores row. The cutting method of every core is modified for reducing the number of facets, making the problem simpler. Finally, an Origami crease pattern based on this new cutting method is presented, producing cores row with any number of cores.

Design of a Novel Flexible Endoscope-Cardioscope

In this paper, we present a novel flexible endoscope which is well suited to minimally invasive cardiac surgery (MICS). It is named ‘the Cardioscope’. The Cardioscope is composed of a handle, a rigid shaft, a flexible section and the imaging system. The flexible section is composed of an elastic tube, a number of spacing discs, a constraint tube and four tendons. Compared with other flexible endoscopes, the Cardioscope is much more dexterous. The maximum bending angle of the Cardioscope is 190°. Ex-vivo tests show that the cardioscope is well suited to (MICS), it provides much larger scope of vision than rigid endoscopes and provides good manipulation inside the confined environment. In the test, the Cardioscope successfully explores the full heart through a single hole, which shows the design is promising. Despite it was designed for MICS, the Cardioscope can also be applied to other minimally invasive surgeries, such as laparoscopy, neurosurgery, transnasal and transoral surgery.

Multistable Behavior of Compliant Kaleidocycles

We present an analysis of the compliant kaleidocycle, a mechanism which, unlike other compliant mechanisms, may undergo continuous rotation. We analyze the strain energy characteristics of this mechanism during its motion and show that by varying the stiffness and orientation of the flexures, kaleidocycles may be designed to achieve customizable multistable behavior. These devices may be designed to include up to four distinct stable equilibrium positions and may also include regions of neutral stability.

Optimization of a Dynamic Model of Magnetic Actuation of an Origami Mechanism

Self-folding origami has the potential to be utilized in novel areas such as self-assembling robotics and shape-morphing structures. Important decisions in the development of such applications include the choice of active material and its placement on the origami model. With proper placement, the error between the actual and target shapes can be minimized along with cost, weight, and power requirements. Through the incorporation of dynamic models of self-folding origami mechanisms into an optimization routine, optimal orientations for magnetically-active material are identified that minimize error to specified target shapes. The dynamic models, created using Adams 2014, are refined by improvements to magnetic material simulation and more accurate joint stiffness characterization. Self-folding dynamic models of the waterbomb base and Shafer’s Frog Tongue are optimized, demonstrating the potential use of this process as a design tool for other self-folding origami mechanisms.

Novel Configurations for Hybrid Transmissions Using a Simple Planetary Gear Train

This paper presents a design approach to systematically synthesize feasible configurations for series-parallel and parallel hybrid transmissions subject to design constraints and required operation modes using a simple planetary gear train (PGT). The configuration synthesis process includes two main steps: 1) assign inputs and output powers to the PGT subject to power constraints by the power arrangement process; and 2) assign clutches and brakes to the obtained systems subject to desired operation modes by the clutch arrangement process. By applying the proposed design approach, nine clutchless and 31 clutched configurations for series-parallel and parallel hybrid systems are synthesized, respectively. For each type of the hybrid systems, we analyzed kinematic and power flow of a new configuration to demonstrate the feasibility of the synthesized systems. The design approach can be used to systematically synthesize future hybrid transmissions with different mechanisms, design constraints, and desired operation modes.

Design of a Soft Multi-Degree of Freedom Tool Positioner With Variable Stiffness Integrating Molded Air Muscles Actuation, Granular Jamming and Dielectric Elastomer Sensing

Soft technology is more and more present in robotics allowing safe interaction with humans, high dexterity in constrained environments, and safe manipulation of fragile or undefined objects. However, soft robotics is limited by a fundamental trade-off between available workspace and stiffness. Position feedback is also challenging as soft robots generally use deformable mechanisms instead of discrete joints. Here, the design of a soft four-degree-of-freedom tool positioner integrating a brake system and a soft sensor is proposed to address these issues. The design integrates molded air muscle actuators, granular jamming brakes, and Dielectric Elastomer Sensors (DES). The design is experimentally validated based on the requirements of a manipulator for liver cancer treatment, which is a representative application of soft robotics. The use of granular jamming mitigates the fundamental trade-off of soft robotics as it allows the manipulator to reach a large workspace (1500 cm3) while having the capacity to provide a high stiffness (up to19 times the initial stiffness). DES provides satisfactory position feedback, demonstrating a 0.69 mm accuracy that is lower than the 1 mm requirement. The proposed design using granular jamming and DES could greatly benefit human-safe and medical robotics.

A Preliminary Process for Origami-Adapted Design

The ancient art of origami has several attributes that are desirable in the design of engineered products such as deployability, stowability, and flat sheet manufacturing. Origami-adapted design aspires to transform the characteristics of an origami paper model into a usable product while maintaining functionality. Engineers have managed to design several origami-adapted products that are innovative in their respective fields. Despite the existence of these origami-adapted products, the process of origami-adapted design is still not well understood. This research seeks to develop an understanding of the origami-adapted design process, the steps involved, and the necessary tools with the goal of promoting the future development of additional origami-adapted products.

A Systematic Exploration of Wing Size on Flapping Wing Air Vehicle Performance

The design of a flapping wing air vehicle is dependent on the interaction of drive motors and wings. In addition to the wing shape and spar arrangement, sizing and flapping kinematics affect vehicle performance due to wing deformation resulting from flapping motions. To achieve maximum payload and endurance, it is necessary to select a wing size and flapping rate that will ensure strong performance and compatibility with drive motor capabilities. Due to several conflicting trade-offs in system design, this is a challenging problem. We have conducted an experimental study of several wing sizes at multiple flapping rates to build an understanding of the design space and ensure acceptable vehicle performance. To support this study, we have designed a new custom test stand and data post-processing procedure. The results of this study are used to build a design methodology for flapping wing air vehicles with improved performance and to highlight system design challenges and strategies for mitigation. Using the methodology described in this paper, we have developed a new flapping wing air vehicle called the Robo Raven II. This vehicle uses larger wings than Robo Raven and flight tests have confirmed that Robo Raven II has a higher payload capacity.

Design Methodologies for Soft-Material Robots Through Additive Manufacturing, From Prototyping to Locomotion

Soft material robots have gained interest in recent years due to the mechanical potential of non-rigid materials and technological development in the additive manufacturing (3D printing) techniques. The incorporation of soft materials provides robots with potential for locomotion in unstructured environments due to the conformability and deformability properties of the structure. Current additive manufacturing techniques allow multimaterial printing which can be utilized to build soft bodied robots with rigid-material inclusions/features in a single process, single batch (low manufacturing volumes) thus saving on both design prototype time and need for complex tools to allow multimaterial manufacturing. However, design and manufacturing of such deformable robots needs to be analyzed and formalized using state of the art tools. This work conceptualizes methodology for motor-tendon actuated soft-bodied robots capable of locomotion. The methodology relies on additive manufacturing as both a prototyping tool and a primary manufacturing tool and is categorized into body design & development, actuation and control design. This methodology is applied to design a soft caterpillar-like biomimetic robot with soft deformable body, motor-tendon actuators which utilizes finite contact points to effect locomotion. The versatility of additive manufacturing is evident in the complex designs that are possible when implementing unique actuation techniques contained in a soft body robot (Modulus discrepancy); For the given motor-tendon actuation, the hard tendons are embedded inside the soft material body which acts as both a structure and an actuator. Furthermore, the modular design of soft/hard component coupling is only possible due to this manufacturing technique and often eliminates the need for joining and fasteners. The multi-materials are also used effectively to manipulate friction by utilizing soft/hard material frictional interaction disparity.