Across UK universities, the continued emphasis on STEM subjects is crucial to develop the skilled engineers of tomorrow. At the University of Bath, the Mechanical Engineering department aims to build knowledge and skills that can be applied to real engineering settings.

For students at the university’s five-year combined degree and master’s degree course studying under Dr Ioannis Georgilas, this culminates in a final-year project that requires the development and prototyping of an innovative device.

Each device must help to resolve a real-world challenge. To develop a prototype, support from sponsors in industry is also usually required, whether to provide components or offer a level of assistance in design integration.

Motion is critical to many of these projects, and the University of Bath has partnered with maxon to provide miniature DC motor and drive system technology through maxon’s Young Engineers Program.

Smart ergonomic work chair

Inspiration for each project typically stems from the real world too, as in the case of this project developed by student Jack Parsons. During long hours seated in front of his computer during a year in industry placement as a product design engineer, he experienced that normal, ‘passive’ office chairs could be a source of back pain – as well as wider health challenges.

Smart ergonomic work chair.

“Research shows that adults working across computer-based jobs would be seated for 70% or more of a typical eight-hour day,” said Parsons. “This sedentary behaviour can result in biomechanical problems, but it can also be bad for overall health, contributing to conditions such as diabetes or heart disease.”

Parsons experimented with ‘active’ chairs, designed to encourage movement while sitting. Typically involving a perching position on an inclined seat, active chairs engage core muscles to maintain stability. Yet this could present its own challenges.

“Active chairs don’t combine the long-term comfort necessary for mental productivity,” he said. “The mental effort required to balance for long periods can be distracting, and you can’t be as focussed on your work while you’re using a percentage of your mind to maintain balance.”

To achieve optimal seating positions, Parsons' design is a hybrid chair that shifts between a passive state, optimising comfort and concentration, with an active state that promotes movement.

A vision system with integrated artificial intelligence (AI) analyses the user’s posture and provides feedback, enabling modification of chair position at defined intervals to balance comfort and activity.

The prototype integrates maxon EC 90 motors, selected for their high torque capacity, necessary to power a chair with an occupant weighing up to 100kg.

The motors were paired with maxon EPOS4 position controllers for precision modulation of the chair’s inclination and height. This drive system also achieves the smooth motion essential for the chair’s safe and comfortable movement with a seated occupant.

For the next design iteration, the hybrid chair could integrate the detection of additional biomechanical landmarks for further fine tuning of position, as well as automating the control of the drive system with the feedback of the vision system.

Miniaturised drug therapy robot

Moving to the field of medicine, a landmark design at the university is a continuum robot project. Like an octopus tentacle, a continuum robot is highly flexible with a wide degree of freedom, achieved by a high number of joints.

As such, continuum robots are an ideal design for invasive therapy, and this ground-breaking arena is the setting for student Max Kienzle’s project to create a continuum robot concept aimed at delivering chemotherapy targeted against tumours.

The advantage of a continuum robot for drug therapy is precise location delivery with the ability to reach space-constrained areas. This is combined with minimal tissue damage for the patient, improving the recovery. While the design is currently a concept, ultimately the device would be delivered to the patient via the mouth with guidance assisted by an endoscope camera.

The robot design involves maxon brushless DC motors that actuate the robot’s tendons in direct drive, with position control provided by a maxon EPOS4 position controller.

The key advantage of the brushless, direct-drive system is improved positional accuracy for finer control. Direct drive also minimises the need for additional sensors and components, resulting in the compact footprint required for the invasive procedure.

“The most significant thing about the project is that previous studies haven’t managed to get down to that size of continuum robot and integrate a direct drive system,” said Kienzle. “We now have the first direct-drive miniature prototype at the university, which has been robust under testing.”

Expanding on the initial concept, the next steps in control design will include the integration of a joystick input sensor to directly command the robot, as well as a camera. As well as necessary enhancements in biocompatibility, the university’s continuum robot concept could then be ready for medical testing.

Variable power assist for pushchairs

As any parent or carer of young children will attest, pushing a pram uphill can be tough. For the University of Bath’s Arthur Anstis, the goal is to create a power assistance device that can be universally attached to any existing pushchair design, making pushing easier and safer.

The concept involves a motorised platform with two wheels that can be integrated to the rear of the pushchair to give power assistance. The wheels are driven by a maxon EC 90 brushless DC motor, chosen for its high torque density and durability, while a maxon ESCON controller manages motor speed.

This set-up achieves customisable power levels based on the user’s needs, with the design capable of assistance on a slope up to 15 degrees – the equivalent of a near 27% incline – with a fully laden maximum weight of 22kg.

Variable power assist for pushchairs.

Speed can be adjusted by the user at the push of a button on a handlebar-mounted trigger press interface. The speed can increase to 7km/ph – the equivalent of a very brisk walk – or even to a running pace for parents or carers who like to exercise with their child and pram.

To ensure safety, a trigger press handle must be engaged for current to be applied to the driving motor. When pressure is released, the system cuts out.

“Anti-skid technology adds a further level of safety, helping to prevent any lateral loss of grip even when extra power is applied,” said Anstis. “This was resolved with an elastic bearing mechanism that counteracts any lateral movement on the rear wheels and helps pull back to a central position.”

While most of the testing has taken place on a tarmac surface using a pair of 160mm wheels, future development could involve different wheel styles for use on alternative surfaces. However, a crucial part of the design innovation demanded a budget that could result in a realistic retail price. This focus has helped to make the design viable for potential commercial development.  

Concepts for tomorrow

While mechanical engineering master’s degree final projects at the University of Bath are primarily focussed on an assessment of the student’s design competence, the resulting concepts are frequently expanded on by students over following years. Some projects are even developed into commercial products.

maxon’s Young Engineers Program not only seeks to support design innovation across engineering sectors, but the success of projects like these also demonstrates the potential of innovation with electric drive systems to improve the challenges of everyday life.