Phased Cam and Linear Actuator Torque Range Control

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Solution Overview

Problem

Existing systems for translating linear motion into rotational torque on a shaft lack efficient control over torque application and range, particularly in varying operational conditions.

Innovation Solution

A system comprising a shaft with cams having involute and circular portions, coupled with linear actuators that detachably engage and disengage based on reference angles and positions, allowing for controlled torque application through hydraulic or pneumatic pressure adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single cam and linear actuator system is used, then the structure is simple, but the control over torque ranges and operational flexibility is limited

Engineering Contradiction:
Improvetorque control rangeVSAvoidcam and actuator configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system divides the cam into multiple segments (first cam with involute portion, second cam with involute portion) that can be independently engaged by different linear actuators. This segmentation allows selective engagement of specific cam-actuator pairs based on operational requirements, enabling variable torque control without requiring a completely different mechanism for each torque level.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system employs dynamic engagement and disengagement of linear actuators with cams based on shaft angle and position feedback. The reference angle and reference position triggers enable the system to adaptively select which cam-actuator pair is active, providing dynamic torque control across different operational phases rather than a fixed configuration.

Inventive Principle:
Principle #15Dynamics

2Productivity

If linear actuators are continuously engaged with cams, then torque is continuously applied, but the ability to optimize torque application based on shaft position is reduced

Engineering Contradiction:
Improvetorque application efficiencyVSAvoidtorque control precision
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The system pre-configures multiple cam profiles with different involute portions designed for specific torque requirements. Before the shaft reaches a particular angular position, the appropriate linear actuator is already positioned and ready to engage with the corresponding cam, ensuring optimal torque application from the outset of each operational phase.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses reference angle and reference position feedback to determine when to engage or disengage linear actuators from cams. This feedback mechanism allows the control system to monitor shaft position and trigger actuator engagement/disengagement at precise moments, optimizing torque application efficiency while maintaining ease of operation through automated control.

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If multiple cams and linear actuators are used, then torque control flexibility is improved, but the system complexity increases

Engineering Contradiction:
Improveoperational flexibilityVSAvoidnumber of cams and actuators
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Each linear actuator is designed to be universally compatible with multiple cam profiles, and each cam is designed with standardized involute portions that can be engaged by any actuator. This universality allows the same actuator-cam components to serve multiple functions across different torque ranges and operational modes, reducing the need for entirely separate mechanisms for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables precise control over torque ranges by engaging and disengaging linear actuators with cams, optimizing torque application based on shaft angles and positions, enhancing operational flexibility and efficiency.

Implementation Method 1

A cross-section of the first cam includes an involute portion. The system additionally includes a second cam coupled to the shaft. A cross-section of the second cam includes an involute portion.

Methodology Applied
Scientific EffectInvolute geometry:

Data Source

PatentEP3253997B1Phased joint cam
Publication Date: 2025.09.24 BOSTON DYNAMICS INC
  • EP3253997B1 patent drawingFigure 1A
  • EP3253997B1 patent drawingFigure 1B
  • EP3253997B1 patent drawingFigure 1C

AI summary

The present disclosure relates to a system that uses linear actuators to generate a torque on a shaft. In an example implementation, a system may include a shaft and an attached cam. The cam includes an involute portion. The system also includes a first linear actuator and a second linear actuator configured to move along a first axis and a second axis, respectively. The linear actuators are configured to detachably couple to the cam based on at least a reference angle of the shaft. That is, as the shaft rotates about its rotational axis at the reference angle, the first and the second linear actuators may couple to, and decouple from, various portions of the cam. As the linear actuators couple to, and decouple from, the various portions of the cam, different rotational torques and/or different ranges of such torques may be imparted onto the shaft.