Table 8.
The advantages and disadvantages of lower limb assisted exoskeletons.
| Type | Energy Storage Element | Advantage | Disadvantage |
|---|---|---|---|
| Powered lower limb assisted exoskeleton | Motor drive | (1) Rapid response and high sensitivity; (2) Easy automatic control; (3) No pollution and low noise; (4) High control precision; (5) High reliability and convenient maintenance | (1) Difficult to control directly and the reducer needs to be connected; (2) Low energy mass ratio; (3) Large inertia and slow steering; (4) Poor cushioning |
| Hydraulic drive | (1) High energy mass ratio; (2) Simple structure and small inertia; (3) Easy to realize overload protection; (4) Driven directly; (5) Good buffer; (6) Easy to realize stepless speed regulation | (1) The working fluid is easy to leak and inconvenient to maintain; (2) The oil is easy to be compressed, and the control accuracy is general; (3) Polluted and noisy. | |
| Pneumatic drive | (1) Driven directly; (2) Low cost; (3) Easy to realize stepless speed regulation; (4) No pollution; (5) Simple system with reliable components; (6) Good buffer | (1) Low energy mass ratio; (2) High noise and easy air leakage; (3) Low control accuracy; (4) Poor structural stiffness; (5) Slow energy transfer and large delay | |
| Unpowered lower limb assisted exoskeleton | Spring energy storage | (1) Lightweight and small volume; (2) Certain gravity compensation; (3) Greatly reduced metabolic energy consumption; (4) Certain support assistance; (5) Hardly affects normal gait | (1) The application scene is limited and interferes with the gait of other scenes; (2) Instability; (3) The spring with large stiffness coefficient makes the wearer feel uncomfortable; (4) The storage and release nodes of energy in gait cycle are fixed; (5) Higher torque is not suitable for patients who need rehabilitation |
| Pneumatic muscle | (1) Adjustable binding force; (2) Higher matching with human muscles; (3) does not affect the free movement of the joint in the swing phase | (1) The timing mechanism needs lubricant added periodically to ensure its correct operation; (2) Device displacement | |
| Four-link structure | (1) High material strength; (2) Springs and damping elements are not used | The auxiliary effect is small at zero load or small load | |
| Adjustable artificial tendon | No energy switching device is required | (1) High quality; (2) Affect normal gait; (3) The wearer will have some discomfort |