Parallel Robotic Wrist with Fixed Actuators

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing robotic devices for manipulating tools with multiple degrees of freedom are bulky and heavy due to the series configuration of drive motors, which limits their dynamics and ability to actuate gripping or cutting tools effectively, especially in confined spaces.

Innovation Solution

A parallel robotic wrist with four actuators fixed to the base, allowing three degrees of freedom in rotation and direct actuation of a gripping or cutting tool through a pivot linkage, reducing moving masses and enabling high-speed operation with reduced bulk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a series configuration with drive motors at each axis is used, then the device can control multiple degrees of freedom, but the device becomes bulky and heavy with large moving masses

Engineering Contradiction:

Improvecontrol of multiple degrees of freedomVSAvoidmoving masses

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent inverts the conventional series configuration by using a parallel architecture where three actuators are fixed to the base and simultaneously control the position and orientation of the end effector through geometric constraints. This inversion eliminates the need for motors at each moving axis, reducing moving masses significantly while maintaining full 6-degree-of-freedom control capability.

Inventive Principle:

Principle #13The other way round (Inversion)

2Weight of moving object

If a parallel configuration with fixed motors is used, then the moving masses are reduced, but the device cannot directly actuate a gripping tool

Engineering Contradiction:

Improvemoving massesVSAvoidactuation of gripping tool

Core Design Contradiction:

Weight of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent integrates a pivot linkage mechanism that serves dual functions: it enables the parallel actuators to control the end effector's position and orientation while simultaneously providing direct actuation of the gripping tool. The pivot linkage acts as a universal mechanism that combines wrist rotation and gripper actuation into a single mechanical architecture, allowing fixed-base actuators to perform both functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Weight of moving object

If a flight simulator configuration with six axes is used, then the motors can be fixed, but the device cannot actuate a gripping tool using motors on the fixed base

Engineering Contradiction:

Improvemoving massesVSAvoidgripping tool actuation

Core Design Contradiction:

Weight of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent merges the wrist rotation function and gripper actuation function into a single integrated mechanism. The pivot linkage combines the degrees of freedom required for wrist orientation with the degree of freedom required for gripper actuation, allowing three fixed-base actuators to control both the end effector position and the gripping tool, eliminating the need for a separate fourth actuator.

Inventive Principle:

Principle #5Merging (Combining)

4Adaptability or versatility

If a series configuration is used to position and orient the wrist, then the device can control tool orientation, but large masses must be set in motion even for small loads

Engineering Contradiction:

Improveorientation of toolVSAvoidmasses to be set in motion

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent inverts the control architecture by using fixed-base actuators that simultaneously determine the end effector's position and orientation through parallel geometric constraints. This inversion eliminates the need to accelerate large moving masses through multiple sequential joints, as the fixed actuators directly control the configuration through the parallel mechanism's geometry.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP3523099B1Parallel robotic wrist with four degrees of freedom

Publication Date: 2020.10.21 ECOLE NAT SUPERIEURE DE MECANIQUE & DES MICROTECHN

Figure 1
Figure 2
Figure 3

AI summary

The device allows the movement of a first movable element (5) about a point with three degrees of rotational freedom and the rotation of a second movable element (6) about the first movable element (5) with one degree of freedom, in order to orient and actuate a working element (7) for gripping or cutting. The device includes at least one base element (1), two movable elements (5) and (6), and four actuators (23) each including a stationary portion (2) and a movable portion (3). The stationary portion of each actuator is rigidly connected to the base element (1), the movable portion of each of same being securely attached to a linking element (4) by means of a ball-and-socket joint (3a). The linking elements (4) are connected to one of the movable elements (5) and (6) via a ball-and-socket joint (5a) or (6a). At least one of the linking elements (4) is connected via a ball-and-socket joint (5a) to the first movable element (5). At least one of the linking elements (4) is connected via a ball-and-socket joint (6a) to the second movable element (6). The first movable element (5) is connected to the base element (1) via a ball-and-socket joint (5b). The movable elements (5) and (6) are connected to one another by a pivot joint (6b). The joints (3a), (5a) and (6a) are arranged so that the rotation of the first movable element (5) with three degrees of freedom as well as the rotation between the movable elements (5) and (6) can thus be controlled by the movement of the movable portions (3) of the actuators controlled by a management computer (12).