Safety Mechanisms

• Research Background
• Safety is one of the key issues in real environments where humans and service robots coexist. 
• A safety mechanism based on passive compliance is desirable since no sensors or actuators are required.

                                                                                      <Human-robot safety>

• Research Objectives
• Safety mechanisms using only mechanical elements (spring, link, cam-camfollower, etc..): Fast response, high reliability and low cost 
• Nonlinear spring system: Both collision safety and positioning accuracy
• Sustained rigidity of the mechanism below the prescribed level of threshold force.
• Sharp increased in compliance of the mechanism above the prescribed threshold force.

                                                    <Nonlinear stiffness of safety mechanism>

Safe Joint Mechanism (SJM)

• Construction of SJM
• Composed of an inclined link, linear guide, roller and springs 
• Capable of adjusting compliance level of the mechanism using the angle of inclination of an inclined link and changing the spring constant and length.

                                                                        <Structure and operational principle of SJM III>

• Features of SJM
• High stiffness of the robot joint can be sustained during tasks subject to forces less than the threshold force.
• The level of the threshold force can be easily adjusted.
• Highly responsive, reliable, no sensors or actuators, and no need for control scheme by using only the passive compliance method
• A small size, light weight, low price safety mechanism

• Research output

• Collision experiments of SJM
• Dynamic collision experiments for the robot arm with and without SJM
• Higher safety for human-robot contact than robot arm without SJM

 

                     

 

 

Safe Link Mechanism (SLM)   Safety link mechanism 내용 삭제

• Construction of SLM
• Composed of double-slider mechanism, spring, wire and shock-absorbing module.
• Capable of adjusting compliance level of the mechanism using the transmission angle of the double slider mechanism and the resistive force of a spring.

                                                           <Structure and operational principle of SLM>

• Features of SJM
• Capable of absorbing the impact forces in all directions.
• High stiffness of the mechanism can be sustained during the tasks subject to forces less than the threshold force.
• The level of the threshold force can be easily adjusted.
• Highly responsive, reliable, no sensors or actuators, and no need for a control scheme.
• A small size, light weight, low price safety mechanism.

• Research output

                                            <Safe Link Mechanism(SLM)>

 

• Collision experiments of SLM
• Dynamic collision experiments for robot arms equipped with and without SLM
• Higher safety for human-robot contact than robot arm without SJM

Safe Joint Module

• Construction of Safe joint module
• Combination of passive and active compliance method
• Safety mechanism for collision absorption with passive compliance method
• Embedded joint torque sensor for collision detection with active compliance method
• Modular type design composed of safety device, gear reducer and bearing

                                                         <Structure of Safe joint module>

• Features of SJM
• Collision absorption using safety mechanism based on cam-cam follower mechanism.
• Collision detection with embedded torque sensor
• Low-cost force control system using embedded torque sensor
• High gear reduction and low backlash with harmonic drive
• Support of moment load by cross-roller bearing
• Hollow shaft for wiring
• Modular type design to construct various types robots 

• Research output