With a current Organizational Structure comprising 10 Agile teams, it's essential to enhance your Agile practices to maintain fast development while boosting software quality. Incorporating robust Agile technical practices such as Test-Driven Development (TDD), Pair Programming, and Continuous Integration can significantly improve code quality.

Frequent code reviews and automated testing should become part of your definition of done to catch defects early. Fostering a culture of collective code ownership and refactoring will also contribute to higher quality software. Your flexibility in accepting new requirements can be maintained through iterative development, but a greater emphasis on technical excellence will ensure that speed doesn't come at the Cost of Quality.

Leveraging Continuous Integration and Continuous Delivery will be pivotal in addressing your software quality issues while maintaining rapid development cycles. Implement a CI/CD pipeline to automate the testing and deployment processes, reducing human error and ensuring that only quality code is deployed to Production.

This pipeline should include stages for unit testing, integration testing, and user acceptance testing to catch defects before they affect users. With software deployed across 50 Manufacturing plants, you'll also need strong rollback mechanisms and canary deployments to minimize the impact of any issues that do slip through.

To ensure high software quality, you should establish a Quality Management System (QMS) that aligns with automotive industry standards such as ISO/TS 16949. This system will provide a structured framework for managing and improving quality at every step of the software development lifecycle.

Implement quality assurance (QA) practices like automated regression tests, performance testing, and static code analysis. Regular QA audits and a defect tracking system will help in identifying trends and areas of improvement. Moreover, your QMS should include training programs to keep your teams updated on Best Practices and quality standards.

To further enhance your software quality while dealing with fast-paced development cycles, consider integrating Robotic Process Automation into your testing and deployment processes. RPA can automate repetitive and rule-based tasks, reducing the strain on your development teams and minimizing human error.

Use RPA bots to perform routine checks and validations, freeing up your developers to focus on more complex testing and Innovation. This not only improves efficiency but also allows for more rigorous testing, enhancing the overall quality of the software deployed in your manufacturing plants.

Integrating Total Productive Maintenance principles with your software development process can improve equipment reliability and operational efficiency. Although TPM is traditionally applied to physical assets, the same concepts can be transferred to software maintenance.

By proactively involving the production operators in the maintenance of the software that they use, you can reduce the frequency and duration of software failures. This can be achieved by training the operators on basic troubleshooting and preventive maintenance practices, thus ensuring that software issues are addressed swiftly and do not hinder plant operations.

Adopt Lean Manufacturing principles to eliminate waste from your development process and improve efficiency. This includes minimizing the 'work in progress' to reduce context-switching and delays, optimizing the flow in your development pipeline, and ensuring that value is continuously delivered to your customers without overburdening your teams.

Lean also emphasizes the importance of building in quality upfront; hence, investing in building quality from the beginning of the software development lifecycle will prevent defects and reduce the need for rework.

As you improve your software development processes, Change Management will be crucial to ensure that changes are smoothly implemented and that the workforce is aligned with the new way of working. This means communicating effectively with all stakeholders about the benefits of the changes, providing necessary training, and establishing Feedback loops to continuously improve the change processes.

In essence, Change Management will support your teams in transitioning to improved practices without Disruption to the ongoing product delivery.

Strive for Operational Excellence in your IT function by continuously seeking to improve processes and eliminate inefficiencies. This involves adopting a mindset of Continuous Improvement, where feedback from production operators and lessons learned from past software deployments are systematically used to make the development and delivery process leaner and more effective.

Operational Excellence will also require you to set and monitor Key Performance Indicators (KPIs) that are linked to software quality and delivery speed to measure improvement over time.

Closely monitor and manage the performance of your software development teams to ensure that you're achieving your goals of fast development and high quality. Define clear metrics for software quality, such as defect rates, and establish performance goals for teams and individuals.

Regularly review these metrics and use them to guide training, resource allocation, and Process Improvements. Recognizing and rewarding high performance will also motivate teams to maintain a focus on quality.

Develop a robust Business Continuity Plan (BCP) that includes your software development and deployment processes. Given that your software is critical to the operation of 50 manufacturing plants, any significant downtime due to software failure could have severe business impacts.

Your BCP should outline steps to recover quickly from software failures, including Disaster Recovery procedures, backup systems, and communication plans for stakeholders. This will minimize operational disruptions and maintain trust with your manufacturing plant clients.