Optimal Design of a Compliant Constant-Force Mechanism to Deliver a Nearly Constant Output Force Over a Range of Input Displacements

Liu, Chih‐Hsing; Hsu, Mao Cheng; Chen, Ta Lun; Chen, Yang

doi:10.1089/soro.2019.0122

Cited by 39 publications

(27 citation statements)

References 41 publications

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“…The first element of (9) gives the common mode force control response, and the second element of (10) gives the differntial mode position control response. The virtual space common mode and differential mode acceleration references are calculated by a force controller (proportional controller) and by a position regulator (proportional derivative controller) as in (12) and (13). The term C p (s) is defined as in (14).…”

Section: Controller Designmentioning

confidence: 99%

“…Casavola et al have proposed constrained teleoperation based on predictive control technique and master-replica command governors for accuracy constraints by putting bounds on the maximum end-effector tracking error concerning the nominal path and constraints on the maximum contact force (11) . Grippers with constant-force mechanism which passively maintains a constant prespecied contact force have been studied for robotic automation, precision manipulation, and overload protection (12) (13) . Arevalo et al have demonstrated the variable stiffness actuator provides compliance and improves the safety features of Cobots in robot-assisted doppler sonography (14) .…”

Section: Introductionmentioning

confidence: 99%

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Excess Force Reduction in Bilateral Control for Precise and Safe Operation

Ruwanthika

Katsura

2022

IEEJ Journal IA

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This paper proposes a constrained bilateral control method to maintain a safe force limit in a remote environment in an event where the operator applies excessive force on the master system. The disturbance observer compensates system disturbances, and the reaction force observer (RFOB) estimates the external force exerted on individual. The paper introduces a force regulator called excess force reduced RFOB (EFR RFOB) to reduce the excessive force applied by the operator to the safe force limit. The amount of excess force is determined by adding the master-side RFOB output and the replica-side safe force limit. Acceleration-based bilateral control is implemented in a virtual space with a master virtual force input, virtual position response, and replica real force-position responses. It realizes transparency in the virtual space. This paper derives the relation between master-side real and virtual space variables to facilitate reproducibility between the master operator and replica environment. The restrained master force-position responses in the virtual space realize precise and safe force control on the replica-side in real space. The proposed method is verified using experiments.

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Section: Controller Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Excess Force Reduction in Bilateral Control for Precise and Safe Operation

Ruwanthika

Katsura

2022

IEEJ Journal IA

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“…2 Soft and compliant robotic systems generally have the potential to handle unexpected interactions with unstructured environments or humans in more sophisticated ways than rigid robots. 3,4 rubber-like resins, 12,14 vulcanized rubbers, 18,19 and thermoplastic elastomers (TPEs) 8,9,11,20 are often used in prototyping soft grippers.…”

Section: Introductionmentioning

confidence: 99%

“…29 The algorithms of topology optimization methods are extensively investigated in the literature over the past several decades [29][30][31][32][33] and have been used in developing various soft robotic grippers. [8][9][10][11]14,16,17,20,[34][35][36][37] For example, Wang et al 10 developed a cable-driven two-finger soft gripper with multiple input ports; a topology optimization method is used to synthesize the compliant finger considering multiple working conditions. A three-finger cable-driven soft robotic gripper presented by Chen et al 35 is prototyped with a 3Dprinted TPE and can be used to grip objects up to 1 kg.…”

Section: Introductionmentioning

confidence: 99%

“…9,11 The numerical results show that the recent finger design 11 is with a lower driving force and a lower maximum equivalent stress during operation comparing to the previous design. 8 To regulate the maximum output force, an absorber-type constant-force mechanism 20 is developed and installed on an electric gripper drive to provide passive force control and overload protection during gripping operation; the numerical computation in Ref. 20 is treated as an error minimization problem between the output and objective forces within a desired input displacement range while updating the density variables to obtain an optimal material layout during topology optimization.…”

Section: Introductionmentioning

confidence: 99%

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Topology Optimization and Prototype of a Multimaterial-Like Compliant Finger by Varying the Infill Density in 3D Printing

Liu

Yang

2022

Soft Robotics

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This study presents a multimaterial topology optimization method for design of multimaterial compliant mechanisms. Traditionally, the objective function in topology optimization for design of structures is to minimize the strain energy (SE). For synthesis of compliant mechanisms, the objective function is usually to maximize the mutual potential energy (MPE). To design an adaptive compliant gripper for grasping size-varied objects, a multicriteria objective function considering both the SE and MPE at two different output ports is proposed in this study. In addition, based on the fact that different infill densities in three-dimensional (3D) printing leads to prototypes with different equivalent mechanical properties, this article proposes that a multimaterial design can be approximated by varying the values of infill densities in different portions of a 3D-printed component, which enables the multimaterial designs to be prototyped using the general low-cost, single-material fused deposition modeling 3D printing machines. The proposed method is used to design and prototype a bi-material compliant finger which is 3D printed using a flexible thermoplastic elastomer with infill densities of 30% and 100%. The experimental results demonstrate that the bi-material finger is a better design in terms of reducing the driving force while increasing the output displacement at the fingertip comparing to the single-material finger design with the same volume and weight. Furthermore, a two-finger gripper with two identical multimaterial-like compliant fingers is prototyped and installed on a six-axis industrial robot. The experimental tests are performed to demonstrate the effectiveness of the presented design.

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Statistical modeling and optimization of process parameters for additive manufacturing of styrene–ethylene–butylene–styrene block copolymer parts using solvent cast 3D printing technique

Kumar,

Pandey,

Jha

et al. 2024

Polymer Engineering & Sci

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Additive manufacturing of thermoplastic elastomers is challenging using fused deposition modeling due to their high melt viscosity, low column strength, and poor fusion among layers. Solvent‐cast 3D printing (SC‐3DP) is an efficient alternative to successfully 3D print such materials. However, selection of suitable 3D printing parameters is crucial to realize parts with optimum physicomechanical properties. In this work, statistical modeling and SC‐3DP parameter optimization for styrene–ethylene–butylene–styrene (SEBS) block copolymer were performed. The effect of 3D printing process parameters on shrinkage, relative density, and tensile strength was analyzed using response surface methodology. Experiments were planned as per central composite design and analysis of variance was performed to evaluate the significant parameters. SEBS content in the polymer solution significantly affected the shrinkage of SC‐3DP samples. Moreover, relative density and tensile strength were significantly affected by print speed and layer height. A significant interaction between print speed and layer height was also noticed for tensile strength and relative density of printed samples. Multi‐objective optimization using genetic algorithm was also performed to minimize shrinkage and maximize relative density and tensile strength. Finally, a case study was conducted comparing the physicomechanical properties of SC‐3DP samples printed at optimized process parameters and compression molded samples.Highlights Statistical models were developed using response surface methodology. Genetic algorithm based multi‐objective optimization was performed. Optimum solvent‐cast 3D printing (SC‐3DP) process parameters were determined.

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Optimal Design of a Compliant Constant-Force Mechanism to Deliver a Nearly Constant Output Force Over a Range of Input Displacements

Cited by 39 publications

References 41 publications

Excess Force Reduction in Bilateral Control for Precise and Safe Operation

Excess Force Reduction in Bilateral Control for Precise and Safe Operation

Topology Optimization and Prototype of a Multimaterial-Like Compliant Finger by Varying the Infill Density in 3D Printing

Statistical modeling and optimization of process parameters for additive manufacturing of styrene–ethylene–butylene–styrene block copolymer parts using solvent cast 3D printing technique

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