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Precision engineering meets cycling
29 April 2024
To help both professional cycling teams and industry manufacturers optimise the performance of their athletes and equipment, Silverstone Sports Engineering Hub turned to Pressure Design and Beckhoff UK to help launch its latest mechanical test rig, the Pedalling Efficiency Rig (PER).
Building power and mastering the art of smooth pedalling constitute two of the most fundamental elements of the journey to becoming a skilled cyclist. While the adage 'practise makes perfect' holds true to an extent, it is only part of the equation – merely spending more time in the saddle does not guarantee improvement, if that time is spent reinforcing inefficient habits.
The introduction of the Pedalling Efficiency Rig by Silverstone Sports Engineering Hub (SSEH) marks a significant advancement in the field of cycling performance testing and optimisation. The PER offers a multitude of benefits for cyclists, professional teams, and industry manufacturers alike.
First, it serves as a highly precise bicycle dynamometer, enabling the measurement of rider input power and the comparison with output power at the roller surface within a controlled environment. This level of accuracy allows for a more comprehensive assessment of the mechanical losses of a bicycle and, consequently, its efficiency.
“This is a really interesting project pushing the boundaries of sport and technology,” said Beth Ragdale, Product Manager at Beckhoff UK.
“The main objectives were to ensure the seamless collection of as much data as possible for analysis, and the representation of this real-time data to the cyclist in a user-friendly manner, while also upholding and prioritising the safety of the cyclist while they’re using the PER.”
The rig consists of a front fork mounting fixture to provide pivot and roll, the bicycle, and an enclosing structure, housing a two-metre diameter roller on which the rear wheel of the bike rests. The roller rotates freely, with interchangeable surfaces, to simulate road conditions, while an integrated electromagnetic resistance mechanism applies variable resistance to replicate real-world cycling forces.
Data collection sensors and measurement devices are strategically placed throughout the rig, capturing crucial metrics such as pedal force, cadence, and power output.
A Beckhoff embedded PC, powered by Beckhoff’s TwinCAT automation software controls the rig, records data and provides feedback to the client. The TwinCAT product covers the suite of software, from the Visual Studio-based development environment, to the runtime PLC application and modular extensions which add the required functionality to each project.
TwinCAT combines programmable logic controller (PLC) functionality with the power and flexibility of PC-based control systems, effectively transforming standard industrial PCs into high-performance control platforms.
TwinCAT's hallmark feature is its support for various programming languages in the development environment, including IEC 61131-3, C/C++, and MATLAB/Simulink, which empowers engineers and developers to choose the language that best suits their requirements.
One of the standout features of the PER is its ability to measure rider input power at the pedals with exceptional precision. Sensors mounted directly around the pedals need to communicate critical data to the system, such as angular velocities and watts – at a rate of 10ms.
Pressure Design utilised Beckhoff’s TCP/UPD real-time library to be able to collect this data in the time required. By isolating left and right-hand inputs and capturing force vectors throughout the crank rotation, the rig can evaluate the pedalling technique's influence on power transmission and efficiency. This capability is crucial for cyclists and coaches looking to refine their pedalling mechanics to unlock higher performance levels.
Unlike other methods currently in use, the PER assesses the whole dynamic system, shedding light on how various components interact to transmit rider power into forward motion. Using the sensors on the rig, 42 channels of data are logged every 10ms; at times, up to eight channels are graphically shown using TwinCAT HMI Scope, and these are displayed on one 50-inch panel in front of the rider and two 27-inch screens in the lab.
This highly accurate data, and the graphing capabilities of the TwinCAT HMI scope, allow the cyclist and technician to analyse and make small changes to the bike to give better performance – and see that change immediately.
"The rig uses TwinCAT Scope which provides the precision required – even below 10ms,” adds Ragdale. “We can mirror what our high-accuracy terminals record on this scope and display it on our HMI. It's all seamlessly embedded in the PLC, allowing us to monitor and analyse the data recorded in real-time, enabling in-depth insights into the process."
The PER goes beyond isolated component testing, and focuses on the bicycle as a complete system. It accounts for rolling resistance, component stiffness, chain friction, and more, ensuring that the interplay between these factors is thoroughly understood. This comprehensive analysis provides valuable data that can guide equipment manufacturers in designing more efficient and responsive bicycles.
To simulate real-world riding conditions, the PER incorporates aerodynamic resistance and gravitational resistance. The electromagnetic resistance brakes apply the appropriate resistance based on wheel speed and a drag-velocity profile, making it possible to replicate the resistance encountered by riders on various terrains and courses. This feature ensures that the rig's testing scenarios closely mimic actual riding conditions, enabling cyclists and teams to optimise their strategies for different race scenarios.
In a paramount commitment to rider safety, the PER is equipped with an advanced safety feature: light curtains. These sophisticated light curtains are strategically positioned on the edge of the rig and connected directly to the Beckhoff safety IO terminals controlled by a TwinSAFE safety solution – a safety technology integrated into Beckhoff's TwinCAT 3 automation software and corresponding hardware platforms – serving as a proactive safety mechanism.
When a rider traverses these light curtains, a seamless and instantaneous response is triggered, automatically disengaging the PER's operation for the utmost safety assurance. The controlled stop is managed within Beckhoff’s multi-axis drive technology, which integrates safety logic directly into the drive and this is incorporated in the same TwinSAFE environment as the light curtains.
The data logging, visualisation application, motion control and this crucial safety feature are all run on Beckhoff’s CX2043 expandable embedded PC. With its state-of-the-art Intel Core i-series processors, the CX2043 packs substantial processing power into a compact form factor, making it an ideal choice for applications ranging from machine control to data acquisition and analysis. Its connectivity options, including multiple Ethernet ports, USB interfaces and PCIe expansion slots, facilitate seamless integration into complex automation systems.
SSEH relied on James Penty, Managing Director at Pressure Design, for his expertise in tying together the multitude of varied sensors in a single system, and extensive automation control knowledge for safety and motion.
"Working with Beckhoff has been a great experience,” said Penty. “Having the ability to reach out to Beth via email or phone for assistance with the challenges we faced throughout this complex system and HMI project has been invaluable. Their support has made a significant difference."
Furthermore, SSEH's forward-thinking approach includes plans for future upgrades, including the option to replace human input with a mechanical system. This enhancement will provide the capability to deliver repeatable input power profiles without the limitations of rider fatigue, making the PER an even more versatile tool for performance evaluation and equipment testing.
The introduction of the PER represents a significant leap forward in the realm of cycling performance testing and optimisation. This state-of-the-art rig offers a multitude of benefits for cyclists, professional teams and industry manufacturers alike.
By providing precise measurements of rider input power and mechanical losses, the PER offers a holistic view of bicycle efficiency, enhancing cyclists' performance and aiding equipment manufacturers in designing more responsive bicycles.
SSEH's forward-thinking plans for future upgrades underscore the rig's potential for even greater versatility and effectiveness in evaluating performance and testing equipment. This collaboration between SSEH, Pressure Design and Beckhoff UK sets a new standard in the quest for optimal cycling performance and safety.
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