Design and Evaluation of Variable Stiffness Actuators with Predefined Stiffness Profiles

Design and Analysis of a Novel Variable Stiffness Joint Based on Leaf Springs

“…In order to compare and analyze the advantages of the proposed VSJ, several similar VSAs are selected for comparison, as shown in Table 3. The stiffness adjustment bandwidth of the VSJ is relatively large when compared to vsaUT-II [20], REGT-VSA [23] and CLSM-VSA [29]. According to the step response simulation analysis, the stiffness regulation time of the VSJ is about 0.34 s, which is relatively fast.…”

“…With the help of this reconfigurable mechanism, the stiffness adjustment range and nominal elastic torque of the VSJ can be easily expanded for a specific requirement without requiring any disassembly and re-assembly of the actuators. Compared with RVSA [31] and CLSM-VSA [29], this design advantage avoids the tedious work of recalibration and debugging required after disassembling the actuator, and has high practical value. However, as it is currently in the conceptual design stage, the weight of the VSJ is only measured using CAD models, resulting in a relatively large theoretical weight.…”

“…In the above stiffness adjustment methods, the physical parameters of the flexible element itself are not changed during the adjustment process, while changing the effective length of the elastic element is a common practice to achieve stiffness adjustment. Typical examples include the parallel double-motor compliant VSJ [26], the mechanical rotary variable impedance actuator (MeRIA) [27], the vsaSDR designed in combination with Archimedes spiral [28], and the variable stiffness actuator based on a cam-leaf spring mechanism (CLSM-VSA) [29], among others. However, in most current designs, the adjustment of the effective length of the elastic element is often achieved using ball screws, gears, or linkages, which can often complicate the joint design, and can only provide a single stiffness range, which is not effective for certain application scenarios.…”