Scaling laws for robotic transmissions

Saerens, Elias; Crispel, Stein; García, Pablo López; Verstraten, Tom; Ducastel, Vincent; Vanderborght, Bram; Lefeber, Dirk

doi:10.1016/j.mechmachtheory.2019.06.027

Cited by 22 publications

(10 citation statements)

References 26 publications

(33 reference statements)

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“…The form is given by y = kx a , where the reference parameter is x and the scaling parameters are k and a. Scaling laws were used for instance for designing complex mechatronic systems [22], for motor geometry design [23] and for designing gearmotors for robots [24] [25]. Scaling parameters used here are summarized in Table II with details in next subsections.…”

Section: Appendixmentioning

confidence: 99%

Multimodal Hydrostatic Actuators for Wearable Robots: A Preliminary Assessment of Mass-Saving and Energy-Efficiency Opportunities

Denis

Lecavalier

Plante

et al. 2022

2022 International Conference on Robotics and Automation (ICRA)

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Wearable robots are limited by their actuators performances because they must bear the weight of their own power system and energy source. This paper explores the idea of leveraging hybrid modes to meet multiple operating points with a lightweight and efficient system by using hydraulic valves to dynamically reconfigure the connections of a hydrostatic actuator. The analyzed opportunities consist in 1) switching between a highly geared power source or a fast power source, 2) dynamically connecting an energy accumulator and 3) using a locking mechanism for holding. Based on a knee exoskeleton case study analysis, results show that switching between gearing ratio can lead to a lighter and more efficient actuator. Also, results show that using an accumulator to provide a preload continuous force has great mass-saving potential, but does not reduce mass significantly if used as a power booster for short transients. Finally, using a locking valve can slightly reduce battery mass if the work cycle includes frequent stops. The operating principles of the proposed multimodal schemes are demonstrated with a one-DOF prototype.

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Section: Appendixmentioning

confidence: 99%

Multimodal Hydrostatic Actuators for Wearable Robots: A Preliminary Assessment of Mass-Saving and Energy-Efficiency Opportunities

Denis

Lecavalier

Plante

et al. 2022

2022 International Conference on Robotics and Automation (ICRA)

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“…If now a transmission would be coupled to the motor, the scaling laws of these transmission need to be known. These are given by [33]:…”

Section: B Parallelization Of Transmissionsmentioning

confidence: 99%

Scaling laws for parallel motor-gearbox arrangements

Saerens

Crispel

García

et al. 2020

2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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Research towards (compliant) actuators, especially redundant ones like the Series Parallel Elastic Actuator (SPEA), has led to the development of drive trains, which have demonstrated to increase efficiency, torque-to-mass-ratio, power-to-mass ratio, etc. In the field of robotics such drive trains can be implemented, enabling technological improvements like safe, adaptable and energy-efficient robots. The choice of the used motor and transmission system, as well as the compliant elements composing the drive train, are highly dependent of the application and more specifically on the allowable weight and size. In order to optimally design an actuator adapted to the desired characteristics and the available space, scaling laws governing the specific actuator can simplify and enhance the reliability of the design process. Although scaling laws of electric motors and links are known, none have been investigated for a complete redundant drive train. The present study proposes to fill this gap by providing scaling laws for electric motors in combination with their transmission system. These laws are extended towards parallelization, i.e. replacing one big motor with gearbox by several smaller ones in parallel. The results of this study show that the torque/mass ratio for a motor-gearbox can not be increased by parallelization, but that it can increase the torque/volume ratio. This is however only the case if a good topology is chosen.

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“…As a high-precision gear transmission mechanism, harmonic drive (HD) is usually composed of flexspline (FS), circular spline (CS) and wave generator (WG). Because of its large transmission ratio, strong bearing capacity and high precision, HD is widely used in aerospace, industrial robots and military equipment [1][2][3][4]. However, CS and FS are special small module gears, which are difficult to manufacture and prone to produce tooth thickness deviation.…”

Section: Introductionmentioning

confidence: 99%

Calculation of tooth thickness errors and its influence on meshing backlash of harmonic drive

Yang

Zhang

et al. 2022

Preprint

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Meshing backlash mainly determines the transmission accuracy of harmonic drive, which is an important index in design. In this paper, a design method of short tooth involute profile is proposed, which relies on positive modification to enhance the strength of dedendum. By intercepting part of tooth profile, the meshing interference of addendum can be effectively avoided. Based on the dimensions of over pins of circular spline and flexspline, a calculation method of tooth thickness deviation is proposed, and the positive and negative of tooth thickness deviation are defined. Involute functions need not be calculated by this method, which simplifies the solution process. By discretizing the teeth profile points of circular spline and flexspline, a calculation method of time-varying backlash is proposed, the variation of backlash in the process of meshing in and out is analyzed, and the influence law of tooth thickness deviation on backlash is studied. On this basis, an algorithm of adjusting the radial deformation to compensate the backlash is proposed. The results show that the excessive backlash in the meshing area can be reduced by increasing the radial deformation. when meshing interference occurs, the interference free meshing can be realized by decreasing the radial deformation.

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Scaling laws for robotic transmissions

Cited by 22 publications

References 26 publications

Multimodal Hydrostatic Actuators for Wearable Robots: A Preliminary Assessment of Mass-Saving and Energy-Efficiency Opportunities

Multimodal Hydrostatic Actuators for Wearable Robots: A Preliminary Assessment of Mass-Saving and Energy-Efficiency Opportunities

Scaling laws for parallel motor-gearbox arrangements

Calculation of tooth thickness errors and its influence on meshing backlash of harmonic drive

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