High-Bandwidth Active Impedance Control of the Proprioceptive Actuator Design in Dynamic Compliant Robotics

Abstract

Dynamic compliant robotics is a fast growing field because of its ability to widen the scope of robotics. The reason for this is that compliant mechanisms may ensure safe/compliant interactions between a robot and an external element-for instance, a human operator. Active impedance control may widen the scope even further in relation to passive elements, but it requires high-bandwidth robust torque and active impedance control which induces high-noise issues even if high-end sensors are used. To address these issues, a complete controller design scheme, including Field-Oriented Control (FOC) of a Brushless Direct Current (BLDC) motor, is proposed. In this paper, controller designs for controlling the virtual impedance, motor torque and field are proposed which enables high-bandwidth robust control. Additionally, a novel speed and angle observer is proposed that aims to reduce noise arising in the angle sensor (typically a 12-bit magnetic encoder) and a Kalman/Luenberger based torque observer is proposed that aims to reduce noise arising in the phase current sensors. Through experimental tests, the combination of the controller designs and observers facilitated a closed-loop torque bandwidth of 2.6 kHz and a noise reduction of 13.5 dB (in relation to no observers), at a sample rate and Pulse Width Modulation (PWM) frequency of 25 kHz. Additionally, experiments verified a precise and high performing controller scheme both during impacts and at a variety of different virtual compliance characteristics.

Framework for Developing Bio-Inspired Morphologies for Walking Robots

“…The anchor morphology helps to protect the robot from fatigue-inducing impulses that, over time, will damage mechanical components, such as gears, bearings and structural components, which ultimately lowers the robot's service life [23,32]. For example, the anchor morphology has an overall lower acceleration level of 7.9% during gait, while the most noticeable difference is the 13.6% lower accelerations of the DOF2 motor.…”

“…The lower step frequency of the anchor morphology also minimizes the number of impulses from foot strikes per distance travelled. Mechanical shock dampeners and/or control strategies can be used to mitigate impulses from foot strikes [32], however, lowering the overall number of impacts per distance travelled lowers the robot's general exposure to impacts and contributes to the extended service life. Subsequently, impact mitigating strategies can be implemented as an addition to lower the detrimental effects even further.…”

Editorial: Biology-Inspired Engineering and Engineering-Inspired Biology

“…The term biology-inspired engineering refers to the fact that biology has been an important inspiration for developments in all aspects of engineering, for example the design of robots. Bio-inspired computation (Manoonpong and Tetzlaff, 2018;Manoonpong et al, 2020), sensors (Steffen et al), actuators (Vanderborght et al, 2013;Dicker et al, 2017;Lee and Oh, 2019;Lund et al, 2019), structures (Tramsen et al, 2018;Tan et al, 2019;Shao et al, 2020), and materials (Rafsanjani et al, 2018;Wang et al, 2020) have enabled robots to produce robust and comparable behaviors to their biological counterparts. Owing to the biologically comparable behaviors, interdisciplinary biologists tend to flip the approach, i.e., engineering-inspired biology, whereby engineering systems and principles are utilized to initiate and test new hypotheses in biological research.…”

Real-Time Implementation of a New MPPT Control Method for a DC-DC Boost Converter Used in a PEM Fuel Cell Power System

“…Therefore, they have been used in many fields such as transportation, aircraft, distributed generation, and especially in stationary and mobile applications [11][12][13][14][15][16][17][18]. In these applications, the PEMFC is usually coupled with a DC-DC power electronic converter that provides an efficient power conversion to the load, and also offers highly regulated output voltage [19][20][21][22][23]. Therefore, the control loop is needed so as to obtain an applicable output dc voltage.…”