Robot Power-Fail Control Using Stored Energy and Staged Braking

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Solution Overview

Problem

Robots face challenges in safely transitioning to a non-operational state during power network failures to prevent damage to themselves and their surroundings, and ensuring immediate readiness upon power restoration without manual intervention.

Innovation Solution

A robot equipped with actuator-driven elements, mechanical brakes, a voltage and current source with an integrated energy store, a monitoring unit, and a control unit that decelerates the robot into a safe state by maintaining operating voltage and current using energy storage, and engages mechanical brakes only when kinetic energy is below a threshold, ensuring safe operation and preventing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical brakes are engaged immediately during power failure, then the robot enters safe state faster, but mechanical damage may occur due to high kinetic energy

Engineering Contradiction:

Improvesafe state entryVSAvoidmechanical damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control unit first drives the actuators to decelerate the actuator-driven elements into a dynamic state with kinetic energy below a threshold before triggering the mechanical brakes. This preliminary deceleration action prevents the harmful effect of mechanical damage while still achieving safe state entry.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the actuators to provide a cushioning deceleration phase before mechanical brake engagement. This cushioning action reduces the kinetic energy to a safe level, preventing damage that would occur from immediate brake engagement at high speed.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Object-affected harmful factors

If actuators are used for deceleration before brake engagement, then mechanical damage is prevented, but the time to enter safe state increases

Engineering Contradiction:

Improvemechanical damage preventionVSAvoidsafe state entry time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The system applies partial action by using actuators only for the portion of deceleration needed to reduce kinetic energy below the threshold, rather than using them for the entire deceleration process. This minimizes the time loss while still preventing mechanical damage.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If energy store maintains operating voltage and current for extended period, then robot readiness is improved, but energy store size increases

Engineering Contradiction:

Improveoperational readinessVSAvoidenergy store capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The energy store is dimensioned to maintain operating voltage and current only for the minimum necessary period to enable safe state entry and immediate readiness upon power restoration. This avoids excessive energy storage capacity while still achieving the required operational readiness.

Inventive Principle:

Principle #16Partial or excessive action

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 safely transition to a non-operational state during power failures, preventing damage and ensuring immediate readiness upon power restoration, enhancing operational safety and reliability.

Implementation Method 1

an energy store (102) which is integrated into the voltage and current source (101) and which, following a failure or a drop in the primary voltage/primary current, maintains the operating voltage UB and the operating current IB for a predefined period of time Δt

Methodology Applied

Scientific EffectEnergy storage: Accumulator (energy)

Implementation Method 2

mechanical brakes (105b) to decelerate the actuator-driven elements (105)

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS11230007B2Robot having a controller protected for a network failure

Publication Date: 2022.01.25 FR ADMINISTRATION GMBH

AI summary

A robot having actuator-driven elements, actuators to drive the elements, and brakes to decelerate the elements, the robot requiring voltage UB and/or current IB, the robot including: a source having an input to which voltage UP and current IP are applied, wherein, during normal operation, UP is equal to voltage UP,desired and IP is equal to current IP,desired, and having an output to which voltage Uactual and current Iactual are supplied, wherein during normal operation: Uactual=UB and Iactual=IB, an energy store integrated into the source for maintaining UB and IB for time Δt following failure or drop in UP and/or IP, a unit for monitoring UP, wherein as soon as UP deviates by amount ΔU from UP,desired, a signal is generated, and a control unit connected to the unit for controlling the robot and its elements into a predefined safe state upon receipt of the signal.