17 accepted papers
We design and experimentally evaluate two anti-backlash mechanisms for cycloidal reducers. The two mechanisms are integrated into variations of a proposed design of quasi-direct drive actuator. Three prototypes are realised to compare the two mechanisms against the baseline design. We evaluate the e…
In the context of safety-critical control, we propose and analyse the use of Control Barrier Functions (CBFs) to limit the kinetic energy of torque-controlled robots. The proposed scheme is able to modify a nominal control action in a minimally invasive manner to achieve the desired kinetic energy l…
We propose a multi-task co-design approach to design a robot's actuation (motor sizes and gear ratios) based on trajectory optimisation. Leveraging an actuation model fit on data of series of components, we find the optimal set of design parameters for all joints over a set of representative tasks f…
We design and experimentally evaluate two anti-backlash mechanisms for cycloidal reducers. The two mechanisms are integrated into variations of a proposed design of quasi-direct drive actuator. Three prototypes are realised to compare the two mechanisms against the baseline design. We evaluate the e
In the context of safety-critical control, we propose and analyse the use of Control Barrier Functions (CBFs) to limit the kinetic energy of torque-controlled robots. The proposed scheme is able to modify a nominal control action in a minimally invasive manner to achieve the desired kinetic energy l
Recent trends in robotic actuation have highlighted the need for low cost, high performance, and efficient gearing. We present an experimental study comparing pinwheel and non-pinwheel designs of cycloidal gearing. The open source designs are 3D-printable, combined with off-the-shelf components, ach…
The recent trend towards low reduction gearing in robotic actuation has revitalised the need for high-performance gearing concepts. In this work we propose compact low-reduction cycloidal gearing, that is 3D-printable and combined with off-the-shelf components. This approach presents an enormous pot…
As situations with robots working in human environments are becoming increasingly important, the aspect of safety is crucial. As a consequence, the design of human friendly robots has been intensively researched in the past years, producing both mechanical and control design advancements. In this wo
In this work, we investigate and validate two methods that can extend the explosive motion capabilities of series elastic actuated robots during standing jumps. First, field weakening control is exploited on multiple joints of a monoped to boost their peak velocities. However, field weakening operat
This work presents the concept of energy-based safety for series-elastic actuation. Generic actuation passivity and safety is treated, defining several energy storage and power flow properties related to passivity. Safe behaviour is not guaranteed by passivity, but can be guaranteed by energy and po…
Torque distribution in redundant robots that combine the potential of asymmetric series-parallel actuated branches and multi-articulation pose a non-trivial challenge. To address the problem, this work proposes a novel optimization based controller that can accommodate various quadratic criteria to…
This work presents the development of a 3-DoF leg with series and parallel compliant actuation. Series-elastic main actuators are combined with parallel high efficiency energy storage branches, to substantially improve energy efficiency. The leg design is semi-anthropomorphic, with similar mass and…
This work presents a method to increase the peak output speed of surface permanent magnet synchronous machine (SPMSM) motor drives with application in robotics using field weakening control. Contrary to most existing works, the strategy is stateless and operates using only a motor torque reference a…
Series-elastic actuators are quickly becoming the core component of robots operating in real-world environments, allowing for robust, safe, torque-controlled robots. This letter investigates the influence of the selected stiffness and control parameters. By consolidating several analyses, it is show
The paper proposes a method to assess the feasible torque bandwidth for electrically driven torque controllable actuators over its entire torque amplitude range. The method solely relies on the knowledge of hardware parameters and thereby determines the physically feasible torque control bandwidth a…
This contribution compares two approaches for applying disturbance observers (DOBs) to the torque control problem of series elastic actuators (SEAs). It is demonstrated that they are in fact equivalent for linear models in terms of their ability to reject disturbances and enforce nominal model dynam…
The development of energy efficient actuation represents one of the biggest challenges in robotics research today. This letter presents the generalisation of design and control concepts for a recently introduced asymmetric compliant actuator, as well as its extension to multi-DoF articulated robotic