Hollow Reducer Tubular Member Encoder Integration
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Solution Overview
Problem
Deflection or wobble in the internal mechanism of a robot's reducer due to insufficient rigidity, which affects the accuracy and positioning of the robot's joints and end effector.
Innovation Solution
A robot design incorporating a hollow reducer structure with a tubular member and a ring-shaped scale member for the output-side encoder, allowing for accurate detection of relative rotation angles between link members, and a power transmission mechanism that reduces motor-induced deflection, along with optical encoders for precise angle detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the motor is disposed at a position away from the rotation axis, then the power transmission mechanism can reduce motor-induced deflection, but the device complexity increases
Solution Approach 1:
The tubular member is disposed inside the hollow part of the reducer, with one end fixed to the input shaft part and the other end protruding from the output shaft part. This nested configuration allows the power transmission mechanism to be integrated within the reducer structure, reducing overall device complexity while maintaining the ability to transmit rotational force accurately.
Solution Approach 2:
The power transmission mechanism acts as an intermediary between the motor and the reducer, transmitting rotation while reducing deflection. The mechanism includes components that transfer rotational motion from the motor's rotation shaft to the reducer's input shaft, enabling precise power transmission without direct coupling that would cause deflection.
2Ease of operation
If the scale member is detachably fixed to the tubular member, then the encoder can be accessed and adjusted easily, but the reliability of the connection may be affected
Solution Approach 1:
The encoder system is segmented into detachable components: the scale member is separable from the tubular member, and the sensor is separate from the scale member. This segmentation allows individual components to be accessed, adjusted, or replaced independently through the hollow part opening, improving ease of operation while maintaining reliable connections through proper interfacing design.
3Reliability
If the hollow part structure is used, then wire integrity is maintained over large operating ranges, but the manufacturing complexity increases
Solution Approach 1:
The hollow part of the reducer serves multiple functions: it provides the structural housing for the reducer, contains the tubular member for power transmission, and creates a protected pathway for wires to pass through. This multi-functionality maintains wire integrity during large operating ranges while avoiding the need for separate wire protection structures, thereby reducing overall manufacturing complexity.
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
Enhances the accuracy and positioning precision of the robot's joints and end effector by mitigating deflection and wobble, while allowing for easy access and adjustment of encoders without disassembly, reducing interference and maintaining wire integrity over large operating ranges.
Implementation Method 1
The output-side encoder is an optical encoder and includes a scale that is provided on one of the adjacent surfaces of the two links adjacent in the direction of the rotation axis and a detection head that is provided on the other one of the adjacent surfaces
Data Source
AI summary
A robot having joint shaft that includes: a first-link member and a second-link that are coupled about a rotation axis; a reducer that has an input-shaft fixed to the first-link and an output-shaft fixed to the second-link; a motor that generates a driving force to be input to the reducer; and an input-side encoder and an output-side encoder. The motor is away from the rotation axis, and a power transmission mechanism is provided between the motor and the reducer. The reducer includes a hollow-part and a tubular-member. The tubular-member passes through the hollow-part, one end of which is fixed to the input-shaft or the output-shaft, and the other end of which protrudes from the input-shaft or the output-shaft. The output-side encoder includes a scale and a sensor. The scale is fixed to the tubular-member; and the sensor is fixed to the input-shaft or the output-shaft.