This paper describes the control method of an electric gripper using a current control system. A current control system was designed and fabricated, and it consisted of a current sensor, an amplifier, and a precision voltage regulator. As a result of calibration by applying the current control system to the electric gripper, the error was less than ±0.34%. The proportional gain for the PI control of the gripper was 0.41, and the integral gain was 0.01. As a result of the control characteristics test, the arrival time was 0.79 s and the steady-state error was ±5 mV (±0.025 N). As a result of the experiment of holding the object, the gripper was able to hold the object safely. Therefore, the electric gripper applied using the current control system performed excellently in current control based on the reference force (grabbing force); thus, it is judged that it can be used to safely grip various objects in various fields.

In this paper, we describe the development of a 5-axis force/moment sensor of an intelligent gripper designed to grasp the weight of an unknown object and the position of the object in the gripper. The 5-axis force/moment sensor consists of an Fx force sensor, Fy force sensor, and Fz force sensor to measure weight, along with an Mx moment sensor and Mz moment sensor to determine the position of an object in the gripper. These sensors are all built within a single body. Each sensor sensing part of the 5-axis force/moment sensor was newly modeled and custom designed using software, and each sensor was manufactured by attaching a strain gauge. The results of the characteristic test of the fabricated 5-axis force/moment sensor showed that the rated output error was within 0.1%, the reproducibility error was within 0.05%, and the nonlinearity error was within 0.04%. Therefore, the 5-axis force/moment sensor developed in this paper can be attached to an intelligent gripper and be used to grasp the weight of an unknown object as well as the position of the object in the gripper.

In this study, we designed and manufactured a 3-axis force sensor for an intelligent gripper that safely grips an unknown object. The 3-axis force sensor consists of an Fx force sensor, an Fy force sensor, and an Fz force sensor in one body, and is manufactured by attaching a strain gauge. The characteristics evaluation showed that the rated output error was within 0.2, the nonlinearity error was within 0.05, and the reproducibility error was within 0.06%. Therefore, the 3-axis force sensor designed and manufactured in this study can be used to measure weight and control the force used to grip an unknown object by attaching it to the intelligent gripper.

Herein, we describe the development of a wearable lower limb rehabilitation robot that can perform walking movement according to the walking pattern trajectory. The robot can adjust the left and right widths of the waist and the front and rear widths of 100 and 20 mm, and the length of the thigh link and calf link by 100 and 80 mm, respectively, so that stroke patients of different heights and weights can use it in hospitals. For manufacturing the lower limb rehabilitation robot, the right exoskeleton was safely designed through structural analysis, and the motor and reducer constituting the hip joint actuator were calculated. The fabricated lower limb rehabilitation robot was divided into its own characteristic experiment and wearing characteristic experiment. Its own characteristic experiment was an experiment by the robot itself, and the wearing characteristic experiment was an experiment conducted after a person wears the robot. Through these two experiments, angular deviation of the walking pattern was analyzed. Results of the analysis confirmed that the wearable walking characteristic test was performed within 3.1° based on the self walking characteristic test result. Therefore, the fabricated lower limb rehabilitation robot can be used for gait training in stroke patients.

This paper describes the design of a 4-axis SCARA-Type robot in the form of a scalar robot for the loading and unloading of workpieces in machine tools. The 4-axis dedicated robot is a 4-degrees-of-freedom robot consisting of a joint 1, 2, 3 motor and a 180° rotating gripper made up of a horizontal gripper and a vertical gripper. It was designed in a scalar shape that is suitable for machine tools, and the size of each link and elbow was determined through structural analysis. Through additional structural analysis, the deflection of the end center of the workpiece fixed to the horizontal gripper and the vertical gripper was designed to be within 0.1 mm, and based on the design result, a 4-axis SCARA-Type robot was manufactured, and the basic motion characteristics of the manufactured robot were tested. As a result of the characteristic test, the manufactured 4-axis SCARA-Type robot operated smoothly, so it is judged to be adequate for usage in loading and unloading the workpieces in machine tools.

In this paper, an integrated ankle torque sensor and mechanism (Foot Link) of a Tendon driven-type wearing walking aid robot were designed. The foot link consists of an ankle torque sensor and a mechanism connected to the footrest. The size of the sensing part of the ankle torque sensor was designed through structural analysis and assembled by attaching a strain gauge. As a result, the reproducibility error and the nonlinearity error were within 0.04%, respectively. And the calibration result of the ankle torque sensor, reproducibility error, and non-linearity error were identified to be within 1%, respectively. Therefore, it is proposed that the ankle torque sensor presented in this paper can be used to measure the torque acting on the tendon-driven walking aid robot.

This paper presents the judgment method of the rehabilitation extent using a spherical type digital finger force measuring system (SDFFMS). Stroke patients can’t use their fingers because of the paralysis of their fingers, but they can recover with rehabilitative training. The SDFFMS has been already developed by Kim (Author of this paper), and the finger grasping forces of normal people and stroke patients could be measured using it. But the SDFFMS could be not used to judge the extent of their rehabilitation, because the judgment method using it is not yet developed. In this paper, the characteristics tests for the grasping forces of normal persons and stroke patients were performed using the SDFFMS, and the judgment method of the rehabilitation extent was developed using the results. The tests confirm that the rehabilitation extent of stroke patients could be judged using the developed judgment method.

This paper describes development of a hand and finger fixing system for the rehabilitation exercise of patient’s fingers. In order to exercise the finger rehabilitation using a finger rehabilitation robot, a patient’s hand or fingers are fixed safely. In this paper, The hand and fingers fixing system can safely fix stroke patient’s hand and fingers by pressing with force control system. The characteristic test of the system was carried out. It is thought that the system could be used for fixing their fingers in stroke patient’s finger rehabilitation exercise.

This paper describes a humanoid robot’s intelligent foot with two six-axis force/moment sensors. The developed humanoid robots didn’t get the intelligent feet for walking on uneven surface safely. In order to walk on uneven surface safely, the robot should measure the reaction forces and moments applied on the soles of the feet, and they should be controlled with the measured the forces and moments. In this paper, an intelligent foot for a humanoid robot was developed. First, the body of foot was designed to be rotated the toe and the heel to all directions, second, the sixaxis force/moment sensors were manufactured, third, the high-speed controller was manufactured using DSP(digital signal processor), fourth, the humanoid robot’s intelligent foot was manufactured using the body of foot, two six-axis force/moment sensors and the high-speed controller, finally, the characteristic test of the intelligent foot was carried out. It is thought that the foot could be used for a humanoid robot.

This paper describes the intelligent robot’s hand with three finger sensors for a humanoid robot. In order to grasp an unknown object safely, the intelligent robot’s hand should measure the mass of the object, and determine the grasping force using the mass, finally control the grasping force using the finger sensors and the controller. In this paper, the intelligent robot’s hand for a humanoid robot was developed. First, the six-axis force/moment sensor was manufactured, second, three finger force sensors were designed and fabricated, third, the high-speed controller was manufactured using DSP(digital signal processor), finally, the characteristic test for determining a grasping force and for grasping an unknown object safely. It is confirmed that the hand could grasp an unknown object safely.

This paper describes the development of wearing intelligent shoe system to measure applied forces and moments (ground reaction forces and moments) on the soles of feet during human walking. In order to walk safely, robot must get the intelligent feet with 6-axis force/moment sensors (Fx sensor (x-direction force sensor), Fy sensor, Fz sensor, Mx sensor (Mx : x-direction moment sensor), My sensor, and Mz sensor) and detect the forces and moments data from the sensors. And the feet must be controlled with the data and controllers. While a human is walking, the forces and moments should be measured and analyzed for robot's intelligent feet. Therefore, the wearing intelligent shoe system should be developed.
In this paper, four 6-axis force/moment sensors and two high speed measuring devices were designed and fabricated, and the wearing intelligent shoe system was made using these. The characteristic tests of the wearing intelligent shoe system were performed, and the forces and moments were detected using it.

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass material, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function on force control and velocity control was developed. It is composed of an electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

This paper describes the development of a high-precision measuring device with DSP (digital signal processor) for the accurate measurement of the 6-axis force/moment sensor mounted to a humanoid robot’s ankle. In order to walk on uneven terrain safely, the foot should perceive the applied forces Fx, Fy, and Fz and moments Mx, My, and Mz to itself, and control the foot using the measured them. The applied forces and moments should be measured from two 6-axis force/moment sensors mounted to the feet, and the sensor is composed of Fx sensor, Fy sensor, Fz sensor, Mx sensor, My sensor and Mz sensor in a body (single block). In order to acquire output values from twelve sensors (two 6-axis force/moment sensor) accurately, the measuring device should get the function of high speed, and should be small in size. The commercialized measuring devices have the function of high speed, unfortunately, they are large in size and heavy in weight. In this paper, the high-precision measuring device for acquiring the output values from two 6-axis force/moment sensors was developed. It is composed of a DSP (150 ㎒), a RAM (random access memory), amplifiers, capacities, resisters and so on. And the characteristic test was carried out.

This paper describes the development of the calibration system for a multi-axis force/moment sensor and its uncertainty evaluation. This calibration system can generate the continuous forces(土Fx, 土Fy and 土Fz) and moments(土Mx, 土My and 土Mz). Many kinds of multi-axis force/moment sensors in industries should be carried out the characteristic test or the calibration with the calibration system that can generate the forces and the moments. The calibration systems have been already developed are the disadvantages of the low capacity, the generation of step forces(10N, 20N …) and step moments(1Nm, 2Nm …) with weights, the high coasts in manufacture and so on. In this paper, the calibration system for a multi-axis force/moment sensor that can generate the continuous three forces and three moments was developed. Their ranges are 0~2000N in all force-directions and 0~400Nm in all moment-directions. And the system was evaluated in the expanded relative uncertainty. They were 土0.0004 in all forces 土Fx, 土Fy and 土Fz, and 土0.0004 in all moments 土Mx, 土My and 土Mz.

This paper describes the development of 6-axis force/moment sensor considered adult weight for an intelligent foot of humanoid robot. In order to walk on uneven terrain safely, the foot should perceive the applied forces Fx, Fy, Fz and moments Mx, My, Mz to itself, and control the foot using the forces and moments. The applied forces and moments should be measured from a 6-axis force/moment sensor attached to the foot, which is composed of Fx sensor, Fy sensor, Fz sensor, Mx sensor, My sensor and Mz sensor in a body. Each sensor should get the deferent rated load, because the applied forces and moments to foot in walking are deferent. Therefore, one of the important things in the sensor is to design each sensor with the deferent rated load and the same rated output.
In this paper, a 6-axis force/moment sensor (rated load of Fx and Fy are 500Nm and Fz sensor is 100N, and those of Mx and My are 18Nm, Mz sensor is 8Nm) for perceiving forces and moments in a humanoid robot's foot was developed using many PPBs (parallel plate-beams). The structure of the sensor was newly modeled, and the sensing elements (plate-beams) of the sensor were designed using by ANSYS software (FEM (Finite Element Method) program). Then, a 6-axis force/moment sensor was fabricated by attaching strain-gages on the sensing elements, and the characteristic test of the developed sensor was carried out. The rated outputs from FEM analysis agree well with that from the characteristic test.