Design and control of a seven-degrees-of-freedom manipulator actuated by a coupled tendon-driven system

Abstract

A seven degrees of freedom manipulator actuated by a tendon drive system has been developed. In order to reduce the weight and volume of the manipulator, each motor was installed on the base frame and the motor torque was transmitted to each joint through a tendon-pulley system. For the tendon drive mechanism, a coupled drive mechanism was introduced, which actuates the manipulator mechanism through controlling the tension of each tendon in the tendon networks designed with coupled tendon structures. In the developed system, eight direct-drive motors and tendon-pulleys were used for a seven degrees of freedom manipulator. In the paper, the structure of the manipulator developed is first explained. Secondly, the tendon tension based control method for the coupled drive manipulator is formulated. Finally, through simple experiments using the manipulator in which the control system was installed, the effectiveness of the proposed structure and the control method were demonstriated.

Tension Control Method Utilizing Antagonistic Tension to Enlarge the Workspace of Coupled Tendon-Driven Articulated Manipulator

“…The most prominent conventional method for solving this problem is to use the pseudo-inverse matrix of the structure matrix. The unified tendon-traction control (UTC) method proposed by Ma [9] is suitable for this purpose and has been also used in other studies [11]. The UTC solution is expressed as Eq.…”

“…Redundancy resolution and tension control methods for tendon-driven manipulators have been studied previously. The most commonly used, conventional resolution approach is the pseudo-inverse matrix method [9], [11], [12]. Iterative algorithms for solving linear problems [13], [14], non-iterative polynomial formulations [15], a closed-form solution using the infinity norm [16], and a sequential calculation method for specific mechanism [17] have also been proposed.…”

Motion control of a virtual humanoid that can perform real physical interactions with a human

“…we can derive the following boundary problem about K and h.K (29) is known as the Riccati equation. The numerical solutions of these equations can be obtained by backward sweeping from t = T to t = 0, which gives K(0) and h(0).…”

“…It generates pure 3-axis forces at the fingertip with a dynamics compensation by commanding the J4 link to generate the forces, to make the acceleration zero and to maintain the posture horizontal. Finally, the joint forces obtained above are transformed to motor torque using a coupled tendondriven control [29]. While it is controlled open-loop by default, an optional small 6-axis force sensor (FS) can be mounted on the J4 link to realize a more precise force display with a disturbance compensation as well.…”

Kinematic design of an anthropomimetic 7-DOF cable-driven robotic arm

“…Other than the well-known commercially successful assistive arms like Handy 1 [4] and MANUS [1], there are also numerous assistive robotic arms that are still under research and development stages. Notable examples include the MATS robotic arm [17], the ARMAR anthropomorphic arm [18,19], the Stanford Arm with a 'Distributed Elastically Coupled Macro Mini Parallel' actuation scheme [20], the magneto-rheological (MR) Safe Arm [21], the 'Safety Serve Manipulator' (SSM) system [22], the 7R anthropomorphic arm driven by pneumatic artificial muscles [23], the 7-DOF tendonactuated arm [24] and the Barrett arm [25]. Although these existing robotic arms possess several features similar to the human arm (e.g., the number of DOFs, joint types, link lengths, and motion characteristics), their mechanism designs and driving schemes are still quite different from those of a human arm.…”