Low backlash gearing for robotics and prosthetics

| Manufacturing

Mousetrap award for low backlash gearing for prosthetics

Gear train design specialists at maxon motor have been developing motors and gears with specific characteristics for robotic and healthcare applications.

Planetary, spur, worm, spindle – when it comes to gearheads maxon motor has produced customised assemblies for every type. In fact, there is a research and development team solely focused on producing systems with special gearheads.

Customers sometimes have very clear ideas about the DC motor and gearhead combination they need but often they look to maxon to find the best customised option. When a customer does not have the time and/or the knowledge to design the drive train, maxon can design, manufacture and test assemblies that meet the customer specifications. The Special Gear Projects team, based at maxon Germany, specialise in creating the best gearhead system that fits between the motor and the customer’s interface.

The maxon team have a lot of experience in the medical industry and also for more industrial applications. Some medical examples are systems for peristaltic pumps, operating robots, injection pumps and surgical tools.

Robot-assisted surgery

The Gear Projects team was approached by a customer who had designed a mechanical actuator assembly using standard maxon motor gear combinations for a surgical robot. The actuator was quite complex with a total of seven motors and gearboxes.

The maxon team saw an opportunity to make the system smaller, more reliable and more efficient. They created a concept for a completely new actuator assembly. maxon not only incorporated the most effective standard maxon motors, custom gear trains and worm gears, but also redesigned the entire actuator assembly.

This assembly included six motorised actuator levers which control the fine movements of the robot’s medical instruments and a motorised track system which allowed forward and backward movement of the medical instruments. Working together with the maxon sensor and control specialists in Switzerland, a drive train with high accuracy and high signal resolution was designed. The new drive train, which still had to fit within the existing customer design constrains, is half the original size and subsequently much lighter but simultaneously more robust.


The team has developed a special low backlash gear motor system for smooth motion with high power density. A typical application for this system would be as a prosthetic “wrist” rotator or various joints for prosthetics, as well as for robotics. This design is especially compact, flat and features a hollow centre shaft so that additional cables or wires can pass through the middle of the assembly. maxon can design a gearhead that has the perfect balance between low backlash and high efficiency for the application.


The Gear Projects Team recently won the 2018 Automation & Motion Control: Robotics award at the Golden Mousetrap Awards for the development of a superior knee joint for an exoskeleton. The drive system uses a maxon EC 90 flat motor with a planetary gearbox and magnet encoder. By designing the entire joint, not just the motor and gear train, the Specialist Gear Project team can merge the motor and gear train into the overall joint assembly, for minimal size and maximum efficiency and performance. The maxon team is already looking at enhancements for the next generation knee joint.

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