Actuator Control Circuit With Hardware Fail-Safe Logic Feedback
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Solution Overview
Problem
Existing control devices for electric actuators rely heavily on microcontrollers for safety functions, leading to potential delays, errors, and lack of feedback, which are critical issues in safety-relevant applications.
Innovation Solution
A control device with a power switching element and sensor means that operates without significant microcontroller involvement, using software-free electrical logic to ensure safe and timely actuation of electric actuators, and providing feedback for diagnostics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If safety functions are provided via software or firmware through a microcontroller, then the control device can perform complex safety logic operations, but this results in time losses due to dead times and program runtimes and introduces source code errors that can lead to system failure
Solution Approach 1:
The patent replaces the software-based microcontroller system with a hardware-based logic assembly consisting of logic gates and circuit elements. This substitution eliminates software execution delays and dead times by performing safety logic operations through direct electrical signal processing in the hardware circuit, thereby resolving the time loss issue while maintaining safety functionality.
Solution Approach 2:
The patent introduces a hardware logic assembly as an intermediary component between the microcontroller and the actuator. This logic assembly processes safety-relevant signals through hardware logic gates before they reach the actuator, providing a dedicated safety pathway that operates independently of software execution and eliminates the need for software-based safety monitoring.
2Reliability
If safety functions are provided via software or firmware through a microcontroller, then the control device can perform complex safety logic operations, but this introduces source code errors that can lead to system failure and lacks internal system diagnostics
Solution Approach 1:
The patent replaces software-based safety functions with hardware-based logic circuits that are inherently more reliable. Hardware logic gates do not suffer from source code errors, buffer overflows, or software bugs. The deterministic behavior of hardware circuits ensures consistent safety logic execution without the harmful factors associated with software implementation.
Solution Approach 2:
The patent implements internal system diagnostics through feedback mechanisms within the hardware logic assembly. The circuit monitors its own operational state and provides diagnostic information about the safety-relevant signals and system status, enabling detection of faults and anomalies without requiring external software diagnostics.
3Ease of operation
If all switching signals run via the microcontroller, then centralized control can be maintained, but this inevitably results in a loss of time due to dead times and program runtimes
Solution Approach 1:
The patent segments the control system into two independent pathways: a main control pathway through the microcontroller for non-safety functions, and a dedicated safety control pathway through the hardware logic assembly for safety-relevant signals. This segmentation allows safety-critical operations to bypass the microcontroller's software execution cycle, eliminating dead times while maintaining centralized control architecture through the overall system integration.
Data Source
AI summary
A control device for fail-safe control of an electric actuator, having: an electrical power source; a power path from the source to an output connection for an actuator, in which a power part is arranged. The power part switches the polarity of the output voltage and/or changes the amount of electrical power that is output. A power switching element in the path switches the electrical power at the output on and off. A sensor downstream of the power part determines the electrical power at the output. An enable signal actuates the power switching element, and a switching signal provides the electrical power at the output based on a switching state. A combinational circuit logic assembly carries out logic operations between the switching state of the switching signal and the electrical power determined by the sensor and generates a further enable signal used to act on the power switching element.