Multifunctional joystick technology solves complex interface challenges in a wide range of medical applications. Precision, quality, ergonomics and haptics are specially tailored into each medical joystick application to offer optimum control and a superior user experience.

Alfred Klein, RAFI-USA

As medical device technology requires more functionality from human operators, combining intuitive and safe joystick operation has become more important. This includes simple applications such as the up-down function for a hospital bed that needs variable speed to extremely critical applications like controlling surgical robots.

Intuitive joystick technology often requires a custom solution to meet the medical application requirements. Joystick technology must not only offer reliable and advanced multifunctional performance that improves human-machine communication, but it must also address safety considerations, the need for sterilization and decontamination, haptics with/without surgical gloves and more. Complex customer-specific control systems may appear to be more expensive than off-the-shelf solutions at first glance. However, when taking a closer look, the numerous advantages will often outweigh the added time or investment.

Customization

In modern medical applications, the joystick handle is typically tailored to the customer’s requirements for a specific application. Customer-specific handle designs are centered around the ease of interface operation and ergonomics, as well as mechanical and electronic performance. Joystick outputs are variable for precise tuning of equipment and critical sensitive movements, where mistakes can be dangerous for both the patient and the doctor. The interface between a doctor or technician and the equipment is the most critical way a company’s brand is identified and differentiated.

As more medical designs demand smaller equipment to offer portability, multi-function joystick controllers help designers overcome space constraints as they incorporate switching and variable output as well as safety functions directly into the grip. The technologies might include rotary function (including rotary encoder), push function (confirmation), buttons with short-travel key-switches, LED indication, thumb joystick, momentary rocker switches, capacitive sensors and near field communication (NFC).

The haptics of a switch within the joystick system is paramount in medical applications. The touch, feel and sound of a switch’s actuation are vital. User interfaces must respond and provide consistent feedback in medical applications to ensure proper and uniform performance. Haptic features are also customized for specific medical joystick systems and are often accomplished by advanced switch configurations that must combine ruggedness with design flexibility.

Environmental performance

Medical equipment is often exposed to rugged conditions such as water, dust, sunlight, vibration and electromagnetic radiation. Joysticks must be designed to handle harsh environments and meet the necessary hygiene regulations. In terms of reliability, strength, hygiene and vandal-proofing, joystick designs in medical electrical equipment must adhere to IEC 60601.

Rugged 3D Hall technology

Joysticks using a zero-wear 3D Hall sensor system offer a compact design with enhanced reliability. Offering at least 5 million operations, zero-wear 3D Hall sensor systems can be designed as a redundant sensor system for applications with extremely high safety requirements. Based on Hall elements, the mechanical design of all components are extremely robust. The metal housing can be made from ferromagnetic steel to ensure optimum shielding of the sensor systems and additional robustness. In a customized design, the mounting hole can also be reduced to minimize the folds in sealing bellows, enabling deeper cleaning. Haptic properties of joysticks with 3D Hall sensor systems can be adjusted by selecting from a variety of compression springs to customize the feel and ease of using the joystick.

Force sensor technology

Force sensor joysticks, which often using strain gauge sensors, offer nearly zero travel operation that results in very little wear and eliminates the need for complicated sealing bellows that can trap germs in medical applications. For this reason, strain gauge joysticks are suitable for use in harsh environments where shock and vibration are common. Force sensor technology is often used on operating tables, where the doctor can precisely move the table via a joystick, with very deliberate, precise movements and feedback. The force sensor in the joystick forwards the signal to the servomotors, which support the movement initiated and thereby reduce the effort involved.

With thorough functional testing, a joystick is individually calibrated prior to shipment in order to eliminate any effects of component tolerances, thermal drifts, etc. over the complete temperature range.

Alfred Klein, CEO of RAFI-USA, is an electrical engineer with a master’s in project management and more than 30 years of designing custom interface solutions for the medical industry.

The opinions expressed in this blog post are the author’s only and do not necessarily reflect those of Medical Design and Outsourcing or its employees.