Active Joint Mechanism Driven by Multiple Actuators Made of Flexible Bags: A Proposal of Dual Structural Actuator

Abstract EN

An actuator is required to change its speed andforce depending on the situation.

Using multiple actuators forone driving axis is one of the possible solutions; however, thereis an associated problem of output power matching.

This studyproposes a new active joint mechanism using multiple actuators.

Because the actuator is made of a flexible bag, it does notinterfere with other actuators when it is depressurized.

The proposedjoint achieved coordinated motion of multiple actuators.

Thisreport also discusses a new actuator which has dual cylindricalstructure.

The cylinders are composed of flexible bags withdifferent diameters.

The joint torque is estimated based on thefollowing factors: empirical formula for the flexible actuatortorque, geometric relationship between the joint and the actuator,and the principle of virtual work.

The prototype joint mechanismachieves coordinated motion of multiple actuators for one axis.

With this motion, small inner actuator contributes high speedmotion, whereas large outer actuator generates high torque.

Theperformance of the prototype joint is examined by speed andtorque measurements.

The joint showed about 30% efficiencyat 2.0 Nm load torque under 0.15 MPa air input.