Dual-Drive Robot Joint Control for Precision and Load Balancing

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing industrial robot joint control systems require identical drives for precision and redundancy, limiting flexibility in mounting orientations and increasing complexity, especially when load balancing is needed.

Innovation Solution

A robot movement control device using two drives with differing accuracy requirements, where the first drive is high-precision and the second drive is lower precision, allowing for load sharing and simplified implementation, and enabling load balancing without complex arrangements, by using a high-precision motor and gear box for the first drive and a lower precision motor and gear box for the second drive.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two identical high-precision drives are used for redundancy and load sharing, then reliability and load capacity are improved, but device complexity and cost increase

Engineering Contradiction:
ImproveredundancyVSAvoiddrive system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by assigning different precision levels to different drives based on their specific functions. The first drive (motor 22 and gear box 20) is designed with high precision for primary position control, while the second drive (motor 36 and gear box 34) uses lower precision components for load balancing and torque control. This differentiation resolves the contradiction by maintaining reliability through functional redundancy while reducing overall device complexity and cost through selective precision application.

Inventive Principle:
Principle #3Local quality

2Force

If load balancing arrangements with springs and counterpoises are used, then load on motor and gear box is reduced, but device complexity and adaptability to different mounting orientations deteriorate

Engineering Contradiction:
Improveload on motorVSAvoidmounting orientation flexibility
Core Design Contradiction:
ForceVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical load balancing system (springs and counterpoises) with a second motor-driven system. The second motor (36) and gear box (34) actively control the load distribution and counterbalance forces through electronic control, eliminating the need for passive mechanical elements. This substitution resolves the contradiction by reducing the load on the primary motor while maintaining adaptability to different mounting orientations through programmable control, unlike fixed mechanical arrangements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If two drives of different accuracy are used, then cost and simplicity are improved, but control precision may deteriorate

Engineering Contradiction:
Improvedrive implementation simplicityVSAvoidcontrol accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent segments the control functions between two drives with different precision capabilities. The first drive (motor 22, gear box 20) handles high-precision position control for the robot joint, while the second drive (motor 36, gear box 34) handles load balancing and torque control functions. The controller coordinates these segmented functions, allowing the system to achieve overall precision through the primary drive while the secondary drive provides cost-effective load management. This segmentation resolves the contradiction by assigning precision requirements only where absolutely necessary.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3448628B1Control of a robot joint using two drives
Publication Date: 2023.02.01 ABB (SCHWEIZ) AG
  • EP3448628B1 patent drawingFigure 1~3
  • EP3448628B1 patent drawingFigure 4~6

AI summary

The invention concerns a robot arrangement, robot movement control device, and computer program product for controlling an industrial robot comprising a moveable arm section, a first motor (22) for moving the arm section, a first gear box between the first motor and the arm section, a second motor (36) for applying torque to the arm section and a second gear box between the second motor and the arm section. The robot movement control device (32) comprises a first control unit (42) configured to control the first motor (22) using position control and a second control unit (44)configured to control the second motor (36) using torque control.