Advanced rehabilitation requires a measurement system that quantitatively analyzes the actions of each individual. Joint moment is an indice used to quantitatively evaluate an individual's actions. Conventionally, force plates and highspeed cameras have been used to analyze joint moments. However, these devices need to be fixed in a laboratory, which limits the measurable motions and measurement range. Further, these sensors are expensive. Hence, it is difficult to use them in medical or nursing care facilities. Therefore, this study aimed to estimate joint moments using inexpensive and wearable sensors. This paper proposes a practical joint moments estimation system using inertial measurement units, which is a wearable sensor. The proposed method uses wearable sensors to measure continuous motion without limitation. It is also cheaper than conventional systems. The effectiveness of the proposed system was verified by comparison with the method using force sensors.

External force detection system plays an important role for robots to operate in the human living environment. Force information determines the interaction between the robot and the environment. However, there are many restrictions on the use of force sensors. Many force sensors are required for wide range contact detection. The force sensor-less method that uses current and angle information is difficult to apply for high reduction ratio mechanisms. In this paper, we propose a method for estimating contact force using one force sensor implemented in the base frame. It is necessary to identify the robot dynamics in order to estimate the contact force. Only the base frame force sensor and encoders are used to identify the dynamics. Therefore, it is very easy to apply. In addition, since it is not affected by joint friction, it can be applied to high reduction ratio mechanisms. The proposed contact force estimation method has a sensitivity for the entire robots. Therefore, contact detection is possible no matter where the force is applied to the robot. The effectiveness of the dynamics identification and the contact force estimation is verified experimentally.

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