Assessment of hand kinematics and interactions with the environment

Measuring hand and finger movements, and interaction forces, is important for the assessment of tasks in daily life. This thesis proposes a new on-body assessment system that allows the measurement of movements and interaction forces of the hand, fingers and thumb. The first thesis objective concerns the development, evaluation and validation of an inertial and magnetic sensing system for the measurement of hand and finger kinematics. The second objective concerns the assessment of the dynamic interaction between human hand and environment using combined force and movement sensing. Chapter 2 describes the inertial and magnetic sensing hardware, and kinematic estimation algorithms for a sensing system which can be attached to the hand, fingers and the thumb. Chapter 3 reports an extensive comparison of this inertial sensing system against a passive opto-electronic marker system under for different tasks that mimic situations in activities of daily living. Chapter 4 describes a new method to ease the typical anatomical segment and sensor calibration procedures by estimating these parameters implicitly along with the estimation of the state variables. In addition, the method incorporates information form chained linkages to circumvent the usage of magnetometers for heading estimation. Chapter 5 presents a solution to estimate the full pose (3D position and 3D orientation) of the hand with respect to the sternum of the body using inertial sensors, magnetometers and a permanent magnet. Contrary to the previous chapters is the magnetic information used to yield a drift free position estimate. Chapter 6 concerns the second research objective which is about the assessment of the physical interaction between the human hand and environmental objects. Dedicated sensors have been applied to measure 3D interaction forces. This hardware has been combined with the inertial hardware presented in the previous chapters and attached to the finger and thumb tips to measure interaction forces and finger motions simultaneously. Eventually the system is used to quantify object dynamics using the information obtained during manipulation.