Empowering a new era of autonomous driving safety with innovative HOD technology

Introduction to the technical features and core competitiveness of the automotive steering wheel hand-off detection pad

Jiangsu Kangwen Technology Co., Ltd. was established in 2020 and is located in Zhenjiang City, Jiangsu Province. It is a high-tech enterprise focusing on the research and development, production and sales of automotive electrical auxiliary equipment. Its core business covers key automotive parts fields such as automotive heating sheets, sensor components, and wire harness processing.

Relying on the accumulation of more than 20 patented technologies (including a number of core automotive electronic patents), the company has formed a full-chain core competitiveness in the field of automotive steering wheel hands-off detection pads (HOD pads) that integrates principle innovation, process optimization, and quality control. It provides high-reliability, highly adaptable hands-off detection solutions for mainstream car companies at home and abroad, and assists in the safe upgrade of automotive autonomous driving technology.

1. Core technology: Innovative principle of automobile steering wheel hand-off detection pad

Steering wheel hands-off detection (HOD_Hands On/Off Detection) is the core safety component of automobile assisted driving and autonomous driving systems. According to international regulatory requirements, new cars equipped with lane keeping assist systems (LKAS) must be equipped with this function. Jiangsu Kangwen has deeply cultivated the capacitive hands-off detection technology route, broke through the limitations of traditional detection solutions, and formed a core principle system that combines accuracy, anti-interference and compatibility. Its technical logic and innovation highlights are as follows:

- Core detection principle: capacitive field sensing and intelligent signal recognition

Jiangsu Kangwen's steering wheel hand-off detection pad adopts a capacitive sensing core design. By constructing a 'sensing layer-shielding layer-isolation layer' three-dimensional structure inside the pad body, it achieves real-time and accurate monitoring of the driver's hand contact status. Its core principle is based on human body static electricity Coupling effect of electric field and capacitive field: The sensing layer of the pad body (using two technical solutions of precise wiring of highly conductive metal wires and plain textile conductive cloth) and the shielding layer (plain textile conductive cloth material) form a stable distributed capacitance loop (sensor and guard) layer), the loop capacitance value remains stable under normal conditions, and the loop voltage signal status is collected in real time through the vehicle ECU (electronic control unit).

When the driver's hand touches the steering wheel, the human body, as a good conductor (generating equivalent capacitance), will form a capacitance parallel effect with the sensing layer, which will significantly increase the total capacitance value of the loop (Csensor+Chand), resulting in a significant drop in the loop voltage. The ECU quickly identifies the voltage change through a built-in algorithm (ΔV), combined with the voltage fluctuation amplitude and duration, can accurately determine the three states of the hand: 'light touch, tight grip, and hand release' without actively turning the steering wheel. Effective detection can be achieved even when the driver wears gloves, which solves the industry pain points of traditional torque measurement methods being susceptible to deception and optical detection methods being costly.

- Innovative breakthrough: anti-interference design and multi-scenario adaptation optimization

In response to the complex electromagnetic environment in the car cabin (such as BCI interference from large current injection, radiation interference from vehicle electronic equipment), Jiangsu Kangwen has optimized the pad structure and signal processing logic through patented technology, achieving a breakthrough in strong anti-interference performance. The company uses high flame retardant and high insulation shielding materials in the design of the shielding layer, combined with the dense wiring process of the sensing layer metal wire and the application of excellent plain conductive cloth to effectively isolate external electromagnetic interference. Ensure that in the international standard BCI test, the signal transmission stability of the pad body meets the functional safety requirements of vehicle regulations and avoid misjudgment or failure problems caused by interference.

At the same time, the company optimizes the sensing layer wiring pattern design based on the structural differences of steering wheels of different car companies, supports the customization of single-zone and multi-zone detection functions, can adapt to various steering wheel shapes such as circular and D-shaped and customer-specific disk shapes, and is compatible with the detection needs of L2-L4 autonomous driving systems at all levels. It provides customized solutions for Volkswagen, Ford, Chery, NIO, Ideal, Hongqi and other car companies.

2. Craftsmanship: refined assembly technology and full-process quality control

Jiangsu Kangwen relies on years of accumulated experience in automotive heating pads and wire harness processing to integrate refined manufacturing concepts into the entire assembly process of off-hand inspection pads. Through patented tooling equipment and standardized operating specifications, it ensures the consistency and reliability of each product. Its core assembly process covers the four major links of 'substrate pretreatment - interlayer composite - wiring welding - packaging inspection'. The key process highlights are as follows:

(1) Substrate pretreatment: precise positioning and smoothing treatment

As the basic carrier of the off-hand detection pad, the substrate's flatness and dimensional accuracy directly affect the sensing performance.

Jiangsu Kangwen uses a self-developed heating sheet substrate gluing device (patent number: CN 222523829 U) to achieve substrate pretreatment through the three-step method of 'adsorption-scraping-projection positioning', laying the foundation for subsequent interlayer compounding and effectively avoiding the problem of sensing blind spots caused by substrate deviation.

(2) Interlayer composite: integrated molding and structural stability assurance

The interlayer composite quality of the hand-off detection pad directly determines its service life and deformation resistance. Jiangsu Kangwen uses a dual fixation process of adhesive + sewing to composite the sensing layer, isolation layer, shielding layer and bottom layer in order: the isolation layer is made of highly elastic and high-temperature-resistant flexible materials to ensure that the pad body can adapt to the arc structure of the steering wheel; the interlayer bonding uses automotive-grade environmentally friendly adhesive, and the pad body base material is used to accurately fix the pad body edge and wiring area to avoid interlayer peeling. It ensures that the pad body does not deform or shift during subsequent processing steps such as secondary foaming of the steering wheel and leather covering, and meets the long-term use requirements of high and low temperature resistance and anti-aging of automotive parts.

(3) Wiring and welding: dislocation design and reliable connection technology

Wiring and welding are the core guarantees for stable signal transmission. Jiangsu Kangwen innovatively adopts the 'dislocation welding + folding wiring area' design to solve the problem of limited internal space of the steering wheel and difficult welding operations. In the design of the wiring area, the welding points of the sensing layer and the shielding layer are misaligned. The wiring area adopts a folding structure and uses the bending space to avoid adjacent welding points. This solves the problem of crowded space in the traditional wiring area and easy welding short circuits; tin dip welding + TPU is used in the welding process. The cover is wrapped with double protection. The heat-shrinkable tube has high-temperature shrinkage and flame-retardant insulation functions, which can effectively protect the welded joints, avoid joint breakage caused by steering wheel deformation or vibration, and improve the service life and reliability of the wiring harness connection.

(4) Packaging testing: full-dimensional verification and precise screening

Jiangsu Kangwen has established a full-process quality control system of 'process inspection + finished product verification' to ensure that each hand-off inspection pad meets industry standards and car company requirements. In the process inspection process, the pad body is laid flat in the inspection tank through the inspection device for automobile steering wheel heating plate production (Patent No.: CN 222528483 U), and the position tolerance of the sensing layer metal wire is quickly detected through the tolerance mark on the transparent inspection plate.

The finished product verification process covers three core tests: First, the capacitance value accuracy test to ensure the fluctuation range of the capacitance value under normal conditions; the company uses independently developed external dimensions and wire harness length inspection equipment to accurately detect the pad body external dimensions and wire harness length to avoid assembly problems caused by pad body shape and wire harness length deviations.

3. The company’s characteristic competitiveness: patent-driven and full industry chain services

Jiangsu Kangwen's core competitiveness in the field of steering wheel hand-off detection pads stems from the trinity development model of 'patented technology leadership, lean manufacturing processes, and customized service adaptation'. The specific features are as follows:

(1) Patent-intensive layout and significant technical barriers

The company has applied for more than 20 patents in total, of which many core patents are directly applied to the R&D and production of hand-off detection pads, covering key aspects such as substrate processing, wiring, welding, and quality inspection (such as heating sheet base material gluing device, steering wheel heating sheet production inspection device, wire harness binding tooling, Sensing layer/solder paste welding of sensing layer, etc.). Through the integrated application of patented technology, the company has formed significant industry barriers in terms of capacitive sensing accuracy, anti-interference performance, assembly efficiency, etc., and its technical level is in a leading position in the country.

(2) Deep integration of processes and double guarantee of production capacity and quality

The company deeply integrates the mature production technology of automobile heating sheets with the technical needs of hand-off detection pads, and realizes the integrated manufacturing of 'sensing layer-shielding layer-heating layer'. It can provide 'hands-off detection + steering wheel heating' two-in-one functional pad body according to the needs of car companies. Reduce the parts assembly process and reduce the procurement costs of car companies. At the same time, the company has established a standardized production workshop, equipped with automated base material processing equipment, precision welding equipment and full-process testing equipment. The annual production capacity can reach more than 800,000 sets, and the product qualification rate is stable at more than 99.7%.

(3) Customized service capabilities to adapt to diverse needs

Relying on its deep understanding of car cockpit structure and autonomous driving technology, Jiangsu Kangwen can provide full-process customized services for different car companies: from early-stage technology docking (optimizing the pad body design based on the steering wheel structure) to mid-term sample trial production (quick response to car companies’ verification needs) , to the later stage of mass production and after-sales guarantee, forming a 'one-on-one' exclusive service system. The company has established long-term cooperative relationships with many mainstream car companies, and its off-hand detection pad products are widely used in passenger cars, commercial vehicles and other models, and have been unanimously recognized by the industry.

4. Summary and Outlook

As an innovative enterprise in the field of automotive electrical auxiliary equipment, Jiangsu Kangwen takes the steering wheel hand-off detection pad as the core gripper, breaks through the industry's pain points through principle innovation, ensures product quality through process optimization, adapts to market demand through customized services, and gradually grows into one of the core suppliers in the domestic hand-off detection field.

In the future, the company will continue to increase investment in research and development, focus on the development trend of autonomous driving technology, delve into core areas such as capacitive sensing technology and intelligent detection, continue to launch more competitive products and solutions, and contribute to the safety and intelligent upgrading of the automotive industry.