Staggered Brake Release Timing for Robot Axis Control
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Solution Overview
Problem
In robot systems with multiple axes, simultaneous release of electromagnetic brakes across axes in a daisy chain coupling leads to a large current flow, causing voltage drops and potential errors, resulting in robot shutdowns due to inrush currents and resistance components in power lines.
Innovation Solution
A robot system with a control device that manages the release timing of electromagnetic brakes across axes differently, using a daisy chain coupling for power and communication lines, allowing for staggered release of braking currents to minimize peak current and voltage drops, thereby preventing errors and shutdowns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If brakes of all axes are released at the same time when motor is turned from OFF to ON, then the robot can quickly become operational, but a large current flows through the power line to generate a voltage drop caused by wire resistance, potentially causing errors and robot shutdown
Solution Approach 1:
The patent divides the simultaneous brake release operation into segmented, sequential releases across different axes. The main controller releases brakes on different axes at different time points rather than all at once, segmenting the current draw over time to avoid peak current surges that cause voltage drops and system errors.
Solution Approach 2:
The patent implements preliminary action by releasing brakes in a predetermined sequence before full operational speed is required. The controller pre-plans the release timing for each axis based on the daisy chain coupling structure, gradually releasing brakes to prevent sudden current surges while ensuring the robot becomes operational without errors or shutdowns.
2Productivity
If brakes are released simultaneously across all axes, then the robot system can start operations quickly, but inrush current and voltage drop cause errors leading to robot shutdown
Solution Approach 1:
The patent applies periodic action by releasing brakes in a time-sequenced manner rather than simultaneously. Each axis experiences brake release at different time intervals, creating a periodic distribution of current demand that prevents peak inrush current while maintaining overall system productivity and avoiding voltage drop-induced errors.
3Device complexity
If a daisy chain coupling is used for power lines, then wiring complexity is reduced, but resistance components in the power line cause voltage drop when large current flows
Solution Approach 1:
The patent segments the power delivery timeline to match the daisy chain wiring structure. By releasing brakes sequentially rather than simultaneously, the current draw is distributed over time, reducing the instantaneous power demand that would cause excessive voltage drop in the resistive daisy chain wiring while maintaining the wiring's simplicity.
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 effectively suppresses voltage drops and inrush currents, ensuring stable operation by optimizing the timing of braking current release across axes, reducing the risk of robot shutdowns and power supply overload.
Implementation Method 1
each of two or more axes may be provided with an electromagnetic brake for holding an attitude of an arm
Implementation Method 2
Such a brake prevents the robot from moving and taking an unintended attitude to come into contact with an object by gravity, vibration, or the like when the robot is short-circuited or a motor is de-excited
Data Source
AI summary
In a robot system, a control device includes a power supplier and a main controller; a robot includes a first controller releasing the braking of a first drive portion by a first braker through a supply of a current from the power supplier and a second controller releasing the braking of a second drive portion by the second braker through a supply of a current from the power supplier; the main controller causes the first controller and the second controllers to release the braking by the first braker and the second braker; a power line coupling the power supplier, the first controller, and the second controller to each other is in a daisy chain coupling; and a first release timing at which the first controller releases the braking by the first braker is different from a second release timing at which the second controller releases the braking by the second braker.