Complete parameter identification of parallel manipulators with partial pose information using a new measurement device

Abstract

A new measurement device is proposed for the calibration of parallel manipulators that can be used to indentify all kinematic parameters with partial pose measurements. The device while restricting the motion of the end-effector to five degree-of-freedom measures three components of posture. A study is performed for a six degree-of-freedom fully parallel Hexa Slide Manipulator. Intrinsic inaccuracies of the measurement device are modeled with two additional identification parameters. Computer simulations show that all parameters, including the additional parameters, can be identified. Results show a significant error reduction, even with noisy measurements, and reveal that the identification is robust against errors in initial guess.

Calibration of Parallel Manipulators and their Application to Machine Tools. A State of the Art Survey

“…A single constraint plane is employed as a mechanical fixture to constrain the motion, and three digital indicators are used as the sensing devices to determine whether the constrained motion is satisfied. Rauf et al (2004) proposes a device to identify all kinematic parameters of a Hexa Slide manipulator. The device consists of a link with U joints on both sides and is equipped with a rotary sensor and a biaxial inclinometer.…”

Are Parallel Robots More Accurate Than Serial Robots?

“…The development of parallel robots has always been driven by promises of (1) greater rigidity, (2) higher speed, and (3) higher accuracy than serial robots.…”

“…[2]; − "Comparing [sic] to the traditional serial-chain mechanism […], the parallel mechanism exhibits the following advantages: […] better accuracy due to non-cumulative joint error." [3] ; − "The errors of parallel manipulators are averaged out in the serial chains and the errors of serial manipulator are accumulated [sic]."…”

An improved method for the geometrical calibration of parallelogram-based parallel robots

“…(3) For parallelogram-based robots, instead of using the position relationship (forward or inverse) as the relation mapping all the variables, one prefers to use directly the raw system of equations (2). Hence, even if the position relationships cannot be derived in a close form, this model can.…”

“…That sensory information can be obtained by using external sensors, by adding extra sensors on the mechanism structure or by restraining the TCP motion through some locking devices. For the two latter solutions, the process is then viewed as self-calibration and an interesting summary of all these calibration techniques is available in [2]. According to the nature of the identified and compensated errors, the calibration can be categorized as geometrical, elastostatic, thermal and dynamic [3][4] [5].…”