Robot Power-Failure Control Using Energy Storage and Safe Braking
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Solution Overview
Problem
Robots with actuator-driven elements face challenges in quickly assuming a safe state and minimizing damage during power supply failures, requiring a solution to ensure immediate restartability after power restoration without causing harm to the robot or its surroundings.
Innovation Solution
A robot with an integrated voltage and current source, including an energy store and a monitoring unit that generates a stop signal when the primary voltage deviates, triggering mechanical brakes on actuator-driven elements only when kinetic energy is below a threshold, ensuring a safe state is achieved without damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical brakes are triggered immediately upon power failure, then the robot is quickly brought to a safe state, but the moving elements may be damaged due to high kinetic energy
Solution Approach 1:
The control unit performs preliminary action by activating actuators to brake the moving elements before power failure occurs. When a power failure is detected, the system has already prepared the actuators to immediately apply braking force, reducing the kinetic energy of moving elements before mechanical brakes engage, thus preventing damage while ensuring safe state achievement
Solution Approach 2:
The actuator-driven braking system serves as a cushioning mechanism that absorbs the kinetic energy of moving elements before the mechanical brakes engage. This preliminary braking action cushions the impact and reduces the force that would otherwise be applied by the mechanical brakes, preventing damage to the moving elements while still bringing the robot to a safe state
2Reliability
If the robot is brought to a safe state quickly after power failure, then functional safety is ensured, but the robot cannot be restarted immediately after power restoration
Solution Approach 1:
The control unit applies partial braking action by using actuators to reduce but not completely stop the moving elements before power failure. This partial action maintains functional safety by reducing kinetic energy to acceptable levels while leaving the system in a state that can be quickly restarted after power restoration, avoiding the need for complete mechanical braking that would require longer restart times
3Object-affected harmful factors
If actuators are used to brake moving elements before power failure, then damage is prevented, but additional energy is consumed
Solution Approach 1:
The system converts the harmful effect of kinetic energy in moving elements into a beneficial braking force. When power failure is detected, the control unit commands actuators to use the motor's electromagnetic braking capability, converting the kinetic energy of moving elements into electrical energy or heat, thus preventing damage while actually utilizing the energy that would otherwise be wasted or harmful
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
The solution enables the robot to maintain operating voltage and current for a specified period, allowing it to transition from any state to a safe state, preventing damage and ensuring immediate restartability after power restoration.
Implementation Method 1
an energy store (102) integrated into the voltage and current source (101), which, after a failure or drop in the primary voltage/current, the operating voltage UB and the operating current IB for a specified period of time Δt maintains
Implementation Method 2
controlling the robot with its elements (105) into a predetermined safe state includes triggering mechanical brakes on the driven elements
Data Source
Figure 1
AI summary
The invention relates to a robot which has actuator-driven elements (105) and requires a desired operating voltage U B and/or a desired operating current I B for operation, comprising: a voltage and current source (101) having an input interface (107), to which a primary voltage U P and a primary current l P are applied, wherein, during normal operation, the primary voltage U P is equal to a desired primary voltage U P,soll and the primary current l P is equal to a desired primary current I P,soll , and having an output interface (108), at which an actual voltage U Ist and an actual current I Ist are provided, wherein the following applies during normal operation: U Ist = U B and I Ist = I B , an energy store (102) which is integrated in the voltage and current source (101) and, after a failure or drop in the primary voltage/primary current, maintains the operating voltage U B and the operating current I B for a predefined period Δt, a unit (103) for monitoring the primary voltage U P applied to the input interface (107), wherein the unit (103) is designed in such a manner that, as soon as the applied primary voltage U P differs from the desired primary voltage U P,soll by a predefined amount ΔU, a stop signal is generated, and a control unit (104) which is connected to the unit (103) and is intended to control the robot and the actuator-driven elements (105) thereof, wherein the control unit (104) is designed to control the robot, with the elements (105) thereof, into a predefined safe state after receiving the stop signal.