Wire-Driven Robot Joint Reducing Motor Load via Ball Screw
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Solution Overview
Problem
Existing robot joint driving systems using reduction units suffer from noise and low efficiency, particularly poor reverse-drivability, which limits effective robot-human interaction, while wire-driven systems face challenges in minimizing motor load during joint operation.
Innovation Solution
A robot joint driving apparatus featuring a reversible drive motor, ball nut and screw parts, a wire connected to both sides of the ball screw, an idle pulley, and a guide member with a support pin to facilitate linear movement and reduce load on the motor, allowing efficient and controlled joint rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a reduction unit is used to drive the joint, then the joint can be driven with mechanical advantage, but the arrangement is limited, noise is severe, and reverse-drivability is poor
Solution Approach 1:
The patent replaces the traditional reduction unit (mechanical gear system) with a wire-driven system. The motor drives a ball screw to convert rotational motion to linear motion of the wire, which then pulls the joint. This substitution eliminates the severe noise and limited arrangement of gear-based reduction units while maintaining mechanical advantage through the ball screw mechanism.
2Power
If a reduction unit is used to drive the joint, then the joint can be driven with mechanical advantage, but reverse-drivability is poor
Solution Approach 1:
The patent replaces the irreversible gear-based reduction unit with a wire-driven system using a ball screw. The ball screw allows bidirectional conversion between rotational and linear motion, enabling the wire to pull the joint in both directions. This provides excellent reverse-drivability, allowing the joint to be driven back to its original position or to any intermediate position, which is crucial for robot-human interaction.
3Object-affected harmful factors
If a wire-driven system is used to drive the joint, then the arrangement is flexible and noise is reduced, but the load on the drive motor is not minimized
Solution Approach 1:
The patent introduces a pulley with a curved surface to redirect the wire. The wire is wrapped around the pulley, which converts the linear motion of the ball screw into the rotational motion needed to drive the joint. This curved path optimization allows the wire to efficiently transmit force while minimizing the load on the drive motor through proper force distribution.
4Device complexity
If the ball screw part performs linear movement directly, then the power transmission is simple, but the load on the drive motor increases
Solution Approach 1:
The patent introduces a pulley as an intermediary component between the ball screw and the joint. The ball screw converts motor rotation to wire linear motion, the pulley redirects this linear motion into rotational motion of the joint, and this intermediate step optimizes force transmission to minimize motor load while maintaining simple overall structure.
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
The solution enables stable and efficient joint rotation with reduced motor load, improving the performance and interaction capabilities of robots by minimizing noise and enhancing reverse-drivability through the use of a wire-driven power transmission structure.
Implementation Method 1
a ball screw part performing linear movement according to the rotation of the ball nut part
Implementation Method 2
a wire connected to first and second sides of the ball screw part
Implementation Method 3
an idle pulley rotatably installed at a first side of the wire
Implementation Method 4
a guide member which allows the ball screw part to perform linear movement
Data Source
AI summary
A robot joint driving apparatus and a robot having the same are capable of minimizing a load applied to a drive motor by rotating a ball nut part such that a ball screw part performs linear movement in a power transmission structure using a wire and the ball screw apparatus. The robot joint driving apparatus includes a reversible drive motor, a ball nut part rotated according to operation of the drive motor, a ball screw part performing linear movement according to rotation of the ball nut part, a wire connected to the ball screw part from both sides of the ball screw part, an idle pulley rotatably installed at one side of the wire, and a joint part rotatably installed at an opposite side of the wire.