Increasing demand for automation and recent intact trends have accelerated the employment of robots in manufacturing and service areas. Thus, there is a growing demand for easier and safer operation of robots, both by experts and non-professionals. This paper proposes a detachable smart robot teaching device with collision prediction to meet such demands. The proposed device is composed of two modules. One is for easy teaching based on a 6D mouse, and the other is for safe operation by measuring the distance to the surrounding obstacles and predicting the collision situation. The teaching module is used only in a teaching phase and can be separated afterward. A prototype is implemented, and the performance is verified through experiments with a collaborative robot.

Robotic manipulators require contact force sensing capabilities to sense the contact force between the manipulator and an object. Specifically, for humans and robots to coexist in the work environment, the robot must be able to detect an external force applied by a human. This study presents a new intrinsic force sensing method for robot manipulators that can obtain accurate information of the external force applied by a human during human–robot interaction. The method employs a robot cover, which is typically utilized in robot manipulators. Unlike conventional force sensing methods, a six-axis force/torque sensor is placed between the cover and the link of the robot manipulator. As a result, the proposed method provides information of the three-axis contact force applied to the cover surface and its contact location. Therefore, the cover itself becomes a sensorized cover based on the intrinsic force sensing method. To evaluate its sensing performance, the sensorized cover is experimentally validated using reference sensors. Finally, an experiment is performed in which the robot successfully recognizes letters written on the cover, indicating a high level of contact force sensing performance.

Demands for human-robot collaboration in production line has increased and the problem of safety in robot becomes more and more important. This paper presents a manipulator with counterbalancing mechanism to secure safety of a human worker in human-robot collaboration environment by reducing a needed power to drive a manipulator. A counterbalancing torque to cancel out a gravitational torque was generated by a restoring force of spring. Also a control algorithm to minimize the effect of spring on tracking performance was proposed. Experimental results were suggested to verify the performance of the proposed method.

Low-cost but high-performance robot arms are required for robot arms to come into widespread use. To provide sufficient torques to support the robot mass and payload, most arms use expensive motors and speed reducers, which are the main reasons for their high price. As a solution to these problems, a multiple-degree-of-freedom (DOF) counterbalance mechanism and robot arm were developed in our previous study, which can compensate for the gravitational torque due to the robot mass. However, there are durability and reliability problems associated with wire-based mechanisms. To solve these, in this study, we proposed a new counterbalance mechanism based on a spring and slider-crank mechanism, along with a double-parallelogram mechanism composed of bevel gear units. Moreover, a 6-DOF counterbalance robot arm was built to verify the performance of the proposed mechanism. Simulation and experimental results showed that the proposed mechanism effectively decreased the torque required to support the robot mass, thus allowing the prospective use of low-cost motors and speed reducers for high-performance robots.

Low-cost but high performance robot arms are required for widespread use of service robots. Most robot arms use expensive motors and speed reducers to provide torques sufficient to support the robot mass and payload. If the gravitational torques due to the robot mass, which is usually much greater than the payload, can be compensated by some means, the robot would need much smaller torques, which can be delivered by cheap actuator modules. To this end, we propose a counterbalance mechanism which can completely counterbalance the gravitational torques due to the robot mass. Since most 6 DOF robots have 3 pitch joints, which are subject to gravitational torques due to the robot mass, we propose a 3 DOF counterbalance mechanism based on the double parallelogram mechanism, in which reference planes are provided to each joint for proper counterbalancing. A 5 DOF counterbalance robot arm was built to demonstrate the performance of the proposed mechanism. Simulation and experimental results showed that the proposed mechanism had effectively decreased the torque required to support the robot mass, thus allowing the prospective use of low-cost motors and speed reducers for high performance root arms.

Collision safety between humans and robots has drawn much attention since service robots are increasingly being used in human environments. A safe robot arm based on passive compliance can usually provide faster and more reliable responses for dynamic collision than an active one involving sensors and actuators. Since both positioning accuracy and collision safety of the robot arm are equally important, a robot arm should have very low stiffness when subjected to a collision force greater than the injury tolerance, but should otherwise maintain very high stiffness. To implement these requirements, a novel safe joint mechanism (SJM-II) which has much smaller size and lighter weight than the previous model, is proposed in this research. The SJM-II has the advantage of nonlinear spring which is achieved using only passive mechanical elements such as linear springs and a double-slider mechanism. Various analyses and experiments on static and dynamic collisions show that stiffness of the SJM-II is kept very high against an external torque less than the predetermined threshold torque, but abruptly drops when the input torque exceeds this threshold, thereby guaranteeing positioning accuracy and collision safety. Furthermore, a robot arm with two SJM-IIs is verified to achieve collision safety in 2D space.