Excavator Actuator Control Reducing Power and Backlash
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Solution Overview
Problem
Existing excavator control methods result in high electrical power consumption during idle periods and backlash issues when releasing the brake, affecting operator comfort and component lifespan.
Innovation Solution
A control method that uses a reversible electric motor and static brake, where the motor is energized to counteract slippage and then releases the brake only after the motor can hold the load, minimizing power consumption and reducing backlash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is continuously energized to immobilize the electric actuators, then the actuators remain stable and immobilized, but electrical power consumption increases significantly
Solution Approach 1:
The control method uses periodic monitoring of motion signals instead of continuous motor energization. The control unit periodically checks motion signals from the motion sensor unit to detect slippage, and only energizes the motor when slippage is detected, transforming continuous power consumption into periodic/conditional power consumption while maintaining immobilization stability
Solution Approach 2:
The static brake is configured to generate brake force to hold the actuator in place without continuous external energy input. The system uses the brake's inherent friction-based holding capability, and only activates the motor when the brake fails to prevent slippage, allowing the brake to serve itself for immobilization while reducing overall power consumption
2Ease of operation
If the brake is released to allow motor control, then the actuator can move smoothly, but backlash occurs in the electric actuator
Solution Approach 1:
The control unit energizes the motor before releasing the brake, so the motor is already generating force to counteract the load. This preliminary motor activation ensures that when the brake is released, the motor is ready to immediately take over load holding, preventing backlash in the actuator mechanism
Solution Approach 2:
The motor acts as an intermediary between the brake and the load. Instead of directly releasing the brake to move the load (which causes backlash), the motor is activated as an intermediate step to share the load, and only after the motor is energized does the brake release occur, smoothing the transition
3Reliability
If the brake force is increased to prevent slippage, then the actuator remains stationary under load, but the risk of backlash increases when the brake is released
Solution Approach 1:
The control unit continuously monitors motion signals from the motion sensor unit to detect slippage. When slippage is detected, the control unit activates the motor to counteract the slippage. This feedback mechanism allows the system to use minimal brake force normally, and only increases motor intervention when needed, reducing the overall risk of backlash while maintaining slippage prevention
Solution Approach 2:
The control method dynamically changes the operational parameters by switching between brake-only mode (normal conditions) and motor-assisted mode (slippage detected). The control unit adjusts the level of motor energization based on the detected slippage, using just enough motor force to counteract the slippage rather than continuously applying maximum force, thereby reducing backlash risk
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 approach reduces electrical power usage by allowing the motor to idle during static load conditions and prevents backlash by ensuring the motor holds the load before brake release, enhancing operator comfort and extending component life.
Implementation Method 1
a static brake configured to generate a brake force so as to brake said electric actuator
Implementation Method 2
an electric motor which is reversible and which is configured to apply a motor force on said electric actuator
Data Source
AI summary
A control method controls a movable member of an excavator including a movable member holding a load, an actuator with electric motor and static brake, a control unit and a motion sensor unit. The static brake and electric motor generate respectively an upper threshold brake force and an upper threshold motor force. An immobilization operation provides that the static brake generates the upper threshold brake force and the electric motor is stopped. A slippage detection operation provides that the control unit detects whether an electric actuator is moving despite the static brake. If the electric actuator is moving, a motor energizing operation provides that the electric motor generates a motor force equal or superior to upper threshold brake force in a direction opposite to the slippage direction. After energizing the motor, a brake release operation provides that the control unit releases the static brake.