A Curved Compliant Differential Mechanism With Neutral Stability

Differential mechanisms are remarkable mechanical elements that are widely utilized in various systems; nevertheless, conventional differential mechanisms are heavy and difficult to use in applications with limited design space. This paper presents a curved differential mechanism that utilizes a lightweight, compliant structure. This...

Compliant variable negative to zero to positive stiffness twisting elements

Compliant mechanisms have the potential to be utilized in numerous applications where the use of conventional mechanisms is unfeasible. These mechanisms have inherent stiffness in their range of motion as they gain their mobility from elastic deformations of elements. In most systems, however, complete control over the elasticity is desired....

Symmetric Kinetostatic Behavior From Asymmetric Spatially Curved Beams

A cantilevered rod's endpoint has a symmetric stiffness profile throughout its range of motion. Generally, this is not the case for spatially curved compliant beams, particularly if they are asymmetric, i.e., their fixation is not in the symmetry plane of their endpoint operating field. This paper discusses a technique for obtaining symmetric...

A compliant Continuously Variable Transmission (CVT)

Continuously Variable Transmissions (CVT) can serve as subsystems for a variety of machineries and robotic systems. A compliant CVT mechanism based on the warping of twisting beams is presented here. The design works based on the demonstrated fact that the twist on one side of a beam can be transferred via sectional warping and propagate...

Characterization of spatially curved beams with anisotropically adaptive stiffness using sliding torsional stiffeners

Compliant mechanisms (CM) with adaptive stiffness have been widely used in robotics and machine design applications. This paper proposes adapting the endpoint stiffness of a spatially curved compliant beam using a movable torsional stiffener and a new graphical characterization method for the resulting anisotropic stiffness of the endpoint...

A Curved Compliant Differential Mechanism With Neutral Stability

Differential mechanisms are remarkable mechanical elements that are widely utilized in various systems; nevertheless, conventional differential mechanisms are heavy and difficult to use in applications with limited design space. In this paper, a curved lightweight compliant type of differential mechanism is presented. This mechanism acquires...

Neutrally stable transition of a curved-crease planar shell structure

Elastic neutral stability in compliant mechanisms is a remarkable appearance since it requires the energetic state of the structure to remain unchanged during a deformation mode. Several examples in literature require either plastic deformation or external constraints to be enforced to obtain a state of pre-stress and often require the use of...

A Design Tool for Passive Wrist Support

A design tool for passive wrist support using compliant spatial beams as gravity balancer is presented. The aim of this assistive device is to reduce required effort for pronation-supination and flexion-extension by 70% to help patients with muscular weakness keeping their hand’s posture and doing daily tasks, while the forearm is rested. To...

Asymmetric Spatial Beams with Symmetric Kinetostatic Behaviour

A method to achieve symmetric kinetostatic behaviour in an extensive working range at the endpoint of an asymmetric spatial beam, using cross-section optimization, is presented. The objective function of the optimization is defined as expanding the beam working range to the desired region, simultaneously maximizing symmetric behaviour in it....

Study on the large-displacement behaviour of a spiral spring with variations of cross-section, orthotropy and prestress

This work is dedicated to the study of the large-displacement behaviour of a spiral spring. Parameters that influence the local torsion stiffness of the beam that constitutes the spiral are varied and their effect is studied. Cross-sectional shape, orthotropic material orientation and prestress are the three classes of parameters that are...

Inspiration from folding patterns

Origami is generally associated with decorative art, not the engineering<br/>world. For some time now, however, engineers have been using the gigantic<br/>database of origami folding patterns as inspiration for designing deployable<br/>mechanisms that can be fabricated efficiently from a flat sheet material.<br/>Most of these mechanisms do not...

Design and optimization of a general planar zero free length spring

A zero free length (ZFL) spring is a spring with special properties, which is commonly used in static balancing. Existing methods to create ZFL springs all have their specific drawbacks, which rises to the need of a new method to create such a spring. A method is proposed to design planar ZFL springs with specified stiffness (250–750 N/m)...

Gravity balanced compliant shell mechanisms

The research on compliant shell mechanisms is a new and promising expansion of the well established compliant mechanisms research area. Benefits of compliant shell mechanisms include being spatial and slender, having organic shapes and their high tailorability of the load-displacement response. This work focusses on the design of a shell with...

Static balancing of an inverted pendulum with prestressed torsion bars

This paper presents a method for the design of a statically balanced inverted pendulum. The non-linear moment-rotation characteristic of the pendulum's weight is approximated by a piecewise linear characteristic. Each transition is realized by engaging or disengaging one or more torsion bars, by means of mechanical stops. The whole set of...

A monolithic compliant large-range gravity balancer

A new monolithic fully compliant gravity balancer is designed with help of a design approach based on shape optimization. The balancer consists of one single clamped-clamped complex-shaped beam on which a weight is attached. The beam is modeled as a planar isogeometric Bernoulli beam. The goal function of the optimization consists of an...

Shape optimization and sensitivity of compliant beams for prescribed load-displacement response

This paper presents the shape optimization of a compliant beam for prescribed load-displacements response. The analysis of the design is based on the isogeometric analysis framework for an enhanced fidelity between designed and analysed shape. The sensitivities used for an improved optimization procedure are derived analytically, including...

A monolithic compliant large-range gravity balancer

A new monolithic fully compliant gravity balancer is designed with help of a design approach based on shape optimization. The balancer consists of one single complex-shaped beam on which the weight is attached. The beam is modeled as a planar isogeometric Bernoulli beam. The goal function of the optimization consists of an energy based...