Page 342 - Flexible Robotics in Medicine

Force sensing in compact concentric tube mechanism with optical fibers 333

Table 14.1: Specifications of Maxon DC motor and HEDS encoder.
DC motor specifications Maxon RE 25 DC motor Encoder specifications HEDS 5540
Dimensions (D 3 H, mm) 25 3 54.5 Encoder counts per turn 500
Mass of motor (kg) 0.13 Max operating frequency (kHz) 100
Max RPM 12,000 Channels 3

Figure 14.5
Actual concentric tube robot.

the assembly base is adequately balanced with the four motors sitting in a circular manner
(Fig. 14.5).

14.4 Kinematic model

The kinematics of CTRs have been explored extensively in previous works by [20,21] that
take into account torsion, bending, and stiffness, as well as real-time inverse kinematics. A
simple kinematic model was developed for the tip-based control of this CTR.