Electric Saw Communication Protocol for Motor Position Feedback

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Solution Overview

Problem

Existing electric saws, particularly wall saws, face challenges in efficiently communicating sensor data and positional information from the saw to the external power supply, leading to difficulties in precise control and automation due to the complexity and weight of hydraulic systems and the need for improved communication protocols.

Innovation Solution

A method is introduced that involves monitoring the electrical position and positional changes of motors in electric saws and transmitting this data to an external power supply, using a three-phase commuted voltage and a binary serial communication protocol with fixed-length packets to facilitate efficient communication between the saw and the power supply, specifically utilizing three-phase permanent magnet motors and Hall Effect sensors for precise control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If hydraulic systems are used to drive wall saws, then power and torque are improved, but weight and ease of setup deteriorate

Engineering Contradiction:
ImprovepowerVSAvoidweight
Core Design Contradiction:
PowerVSWeight of moving object

Solution Approach 1:

The patent replaces the hydraulic mechanical system with an electric motor system. The electric motor (110) directly drives the saw blade (103) through a transmission mechanism, eliminating the need for hydraulic pumps, hoses, and fluid power systems. This substitution significantly reduces the overall weight of the wall saw while maintaining sufficient cutting power through optimized electric motor selection and direct-drive architecture.

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

2Weight of moving object

If electric motors are used instead of hydraulic systems, then weight and ease of setup are improved, but control precision and automation capability deteriorate

Engineering Contradiction:
ImproveweightVSAvoidautomation capability
Core Design Contradiction:
Weight of moving objectVSExtent of automation

Solution Approach 1:

The patent implements feedback control through encoders (116, 136) that continuously monitor the position and speed of motors (110, 120, 130). This feedback is transmitted to the control unit (160), which adjusts motor commands in real-time to maintain precise control over saw blade position, carriage movement along the rack (108), and depth control. This closed-loop feedback system enables automation capabilities despite the lighter electric construction.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control unit (160) serves multiple functions: it controls the main drive motor (110), the carriage positioning motor (120), the depth control motor (130), and processes feedback from encoders. It also manages communication with the power supply unit (102) and implements safety interlocks. This multi-functional control system consolidates automation capabilities into a single electronic brain, enabling precise control of the simplified electric architecture.

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

3Measurement precision

If sensor data transmission is implemented from saw to power supply, then control precision is improved, but communication complexity deteriorates

Engineering Contradiction:
Improvesensor data accuracyVSAvoidcommunication complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple communication functions into a single integrated communication bus between the control unit (160) and power supply unit (102). This bus transmits both power control signals and sensor feedback data (position, speed, temperature) bidirectionally. By merging control and communication channels into one unified interface, the system reduces the number of separate wiring harnesses and communication protocols needed, thereby reducing overall system complexity while maintaining high measurement precision.

Inventive Principle:
Principle #5Merging (Combining)

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 solution enables efficient and precise control of electric saws by ensuring accurate transmission of positional data and temperature information, enhancing automation and reducing the complexity and weight associated with hydraulic systems, thereby improving the operational efficiency and ease of use of electric saws.

Implementation Method 1

utilizing three-phase permanent magnet motors and Hall Effect sensors for precise control

Methodology Applied
Scientific EffectHall Effect: Hall Effect

Data Source

PatentEP2278699B1Electric saw communication
Publication Date: 2019.10.30 HUSQVARNA AB
  • EP2278699B1 patent drawingFigure 1
  • EP2278699B1 patent drawingFigure 2
  • EP2278699B1 patent drawingFigure 3~4

AI summary

The present invention relates to an electric saw (1) being powered by an external power supply (200) through a multicore cable. The multicore cable includes electrical wires (24, 25, 27) for supplying power to the motors (5, 12, 13) of the electric saw (1) and communication wires (26) for data communication between the electric saw (1) and the power supply (200). Two motors (12, 13) of the electric saw are three phase permanent magnet motors (12, 13), with an outer rotor and an inner stator. Each of the two motors (12, 13) has three Hall Effect sensors (H1, H2, H3) located around the outer rotor. In particular the invention relates to a method of controlling the saw (1) comprising the steps: a) monitoring the electrical position and/or electrical positional changes of the second and/or third motor (12, 13); and b) transmitting it to the external power supply (200); and c) delivering a three phase commuted voltage to the second and/or third motor (12, 13). Further the invention relates to a communication protocol for serial communication between the saw (1) and the external power supply (200).