Cable Deceleration Mechanism for Compact Robotic Arm Joints
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Solution Overview
Problem
Existing arm devices for remote operation robots, such as surgical robots and operation console devices, face challenges in miniaturization due to the size of motors required for active joints, which limits their application in confined spaces and requires a deceleration mechanism to achieve the necessary torque without increasing device size.
Innovation Solution
The implementation of a cable deceleration mechanism with an idler pulley inserted between the input and output capstans allows for a compact design by maintaining the deceleration ratio while providing a sufficient radial clearance for motor placement, thus avoiding interference and enabling a smaller device footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a motor with increased diameter or rotation axis length is used to output larger rotational torque, then the rotational torque is improved, but the device size increases
Solution Approach 1:
A cable deceleration mechanism is introduced as an intermediary between the motor and the active joint. This mechanism includes a input capstan attached to the motor output shaft, an output capstan attached to the active shaft, and a cable wound around both capstans. The cable deceleration mechanism transmits and amplifies the motor's rotational torque to the active joint, allowing the use of smaller motors while achieving the required torque output at the joint.
2Volume of moving object
If a cable deceleration mechanism is used to convert motor torque, then the device size is reduced, but the radial clearance for motor placement is insufficient
Solution Approach 1:
The cable deceleration mechanism utilizes the axial dimension (along the rotation axis) to achieve torque multiplication, rather than requiring additional radial clearance. The input capstan and output capstan are arranged coaxially, with the cable winding around both capstans in sequence. This configuration allows the motor to be placed in the axial direction without interfering with the cable path, effectively resolving the radial clearance constraint while maintaining compact device dimensions.
3Adaptability or versatility
If an idler pulley is added between input and output capstans, then the motor arrangement flexibility is improved, but the device complexity increases
Solution Approach 1:
An idler pulley is introduced as an intermediary component between the input capstan and output capstan. The idler pulley guides the cable from the input capstan to the output capstan, allowing for flexible motor arrangement and optimized cable routing. By positioning the idler pulley strategically, the mechanism achieves improved motor placement flexibility while the cable path remains efficient, balancing the added complexity with enhanced design adaptability.
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
This configuration achieves backlashlessness and high backdrivability, enabling precise force control and maintaining the movable range of the cable deceleration mechanism, while allowing for a more compact and efficient arm device design.
Implementation Method 1
a cable deceleration mechanism including an input capstan attached to an output shaft of a motor, an output capstan attached to an active shaft, an idler pulley disposed between the input capstan and the output capstan, and a cable wound around an outer periphery of each of the input capstan and the output capstan via the idler pulley
Data Source
AI summary
Provided is an arm device in which a cable deceleration structure with improved degree of freedom of arrangement of a motor is applied to an active joint. The arm device includes one or more active shafts and includes an input capstan attached to an output shaft of a motor for driving at least one active shaft of the one or more active shafts, an output capstan attached to the at least one active shaft, an idler pulley disposed between the input capstan and the output capstan, and a cable wound around an outer periphery of each of the input capstan and the output capstan via the idler pulley.