Robot Drive Unit DC-Bus Voltage Control for Safe Teach Mode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Industrial robots in teach mode still experience fast movements due to higher than necessary voltage levels, posing safety risks to operators despite reduced speed, as the predetermined voltage levels are fixed and cannot be easily adjusted.
Innovation Solution
A method and robot drive unit that dynamically calculate and set the DC-bus voltage level based on the actual need for each robot movement, with a margin to ensure safety, and include an emergency stop mechanism to prevent excessive voltage levels, allowing for multiple operation modes with distinct maximum voltage levels and frequent voltage adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the teach mode voltage level is set to the worst case maximum motor voltage, then the robot can handle any teach sequence movement, but the voltage level remains much higher than required for the majority of teach sequence movements, causing unnecessary fast robot movements and safety risks
Solution Approach 1:
The patent applies dynamics by making the DC-bus voltage level adjustable and adaptive rather than fixed. The voltage level is dynamically modified based on the actual movement requirements detected during teach operations, allowing the system to transition from a static high voltage level to a dynamic level that matches actual needs, thereby preventing unnecessary fast movements while maintaining reliability
Solution Approach 2:
The patent changes the voltage parameter from a fixed predetermined value to a variable that can be modified during operation. By detecting when the robot is in teach mode and adjusting the DC-bus voltage level accordingly, the system optimizes the voltage parameter to match actual requirements, eliminating the safety hazard caused by excessively high voltage levels
2Device complexity
If a fixed predetermined voltage level is used in the DC-bus, then the system is simple to implement, but the voltage level cannot be adjusted to match actual movement requirements, leading to safety issues
Solution Approach 1:
The patent implements feedback by detecting the operational mode (teach vs. auto) and using this information to adjust the DC-bus voltage level. The system continuously monitors operational conditions and modifies the voltage accordingly, creating a closed-loop control system that enhances safety without requiring complex hardware modifications
Solution Approach 2:
The patent makes the voltage control system multi-functional by enabling it to serve different purposes in different operational modes. The same DC-bus and voltage control infrastructure is used for both auto mode (high performance) and teach mode (enhanced safety), eliminating the need for separate dedicated systems while achieving mode-specific optimization
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
Prevents unnecessary fast robot movements by ensuring the voltage level matches the required movement speed, enhancing safety by limiting motor speeds to prevent injuries and providing an additional safety function through emergency stops, even if the voltage calculation fails.
Implementation Method 1
a DC-bus supplying current to motors at robot axes
Data Source
AI summary
For controlling a robot in a safe way, a highest voltage required for a desired robot movement is calculated. A voltage level in a DC-bus is set on the basis of the highest voltage, and current is supplied to a motor at a robot axis from the DC-bus. By limiting the voltage level in the DC-bus to correspond to an actual need for a desired robot movement at each instant unnecessary fast robot movements are prevented even in the event that an inverter controlling motor currents would by mistake attempt to drive the motor faster than desired by the operator.