Design and control of a mechanical rotary variable impedance actuator

Design and analysis of spring parallel variable stiffness actuator based on antagonistic principle

“…And the angles γ j and ε j are solved by geometric relations, sin γ j = sin α j • sin β (11) sin ε j = sin α j • cos β cos γ j (12) where β is the angle between the plane of two wire ropes and XOZ, ε j is the angle between the projection of the wire ropes on XOZ and the direction of OX, and γ j is the angle between the wire ropes and projection of the wire ropes on XOZ.…”

“…Fang et al [2] changed the effective length of the leaf spring by changing the position of fixing point (anchor) of the leaf spring by the epicyclic gear train to achieve the joint stiffness adjustment. Using the same principle, variable stiffness joints also include VsaMGR [11] and MeRIA [12] . Almost all external loads of these joints act on the leaf spring, which requires high demands on the strength of the leaf spring.…”

Active Impedance Control of Bioinspired Motion Robotic Manipulators: An Overview

“…Therefore, Santina et al [ 147 ] showed that using a feedforward control loop combined with a low-gain feedback gain can achieve better-desired behavior comparing with feedback control schemes The constant impedance actuators described above may have limitations associated with dealing with the different tasks and motion frequencies; the different tasks need variable stiffness (impedance) actions that could be lost in the SEAs. Therefore, robotic systems with VSAs are capable of rejecting disturbances, storing energy, and controlling the end effector stiffness in contact space [ 41 ]; see [ 20 – 22 , 148 ] for details on the design, performance, and classification of VSAs In general, there are three control schemes of VSAs: (i) simultaneous control of position and stiffness control [ 149 ], (ii) impedance control with inner torque control [ 150 , 151 ], and (iii) bioinspired control, e.g., time-based compliance control [ 152 ] and coactivation control [ 153 – 155 ] The proposed control schemes, the performance, and stability have not yet been extensively investigated. The stability of impedance control associated with VSAs requires more research.…”

“…However, impedance control associated with inner torque control is the easiest control scheme to deal with constant and VSAs. For more details on the control architecture and stability of VSAs, see [ 149 – 151 , 156 – 169 ]…”

Classification of Variable Stiffness Actuators - part 2

“…Układ zapewnia możliwość regulacji podatności w szerokim zakresie. Wadą są duże gabaryty urządzenia [16]. Řʊ˿ǞǘŘƋǖŘ ʊǜŘ˹ɂ˹ Ɂ ˘ȧǔƬȭȭƬǖ ɡɁƞŘǜȭɁʋƋǔ ȧƬƋǒŘȭǔƋ˘ȭƬǖ ǂ Ƌ˘DŽʋƌ ʹ utrudni ich wzajemny poślizg.…”