Introducing a Formal High-Level Language for Instructing Automated Manikins

Paper in proceeding, 2013

Digital Human Modeling programs are important tools in virtual manufacturing that allow simulation of manual assembly work, long before any physical product has been built. By investigating the logistics, ergonomics and the interaction among the workers at an early stage, it may be possible to reduce the cost of design changes, increase the quality and to decrease the ramp-up time of a manufacturing process. However, far from all assembly operations are simulated, even if all the necessary data is available. One reason is the tedious work required to setup and to define all the motions needed by a manikin to perform a simulation. In each simulation, the manikin must be adjusted into the desired posture and the user must ensure that balance is held and that it avoids collision with objects in the environment. Thus, even a small case may be time consuming to simulate. This shows that there is a need of an easier way of instructing the manikins. In this work we propose a new formal high-level language for controlling an automated manikin. The language instructions are structured by a grammar, which defines a hierarchical tree for the manikin instructions. The low- level instructions contains basic functionality for maneuvering the manikin, such as Move, Position and Grasp, and higher levels contain more abstract instructions such as Get and Assemble. Thus, the high-level instructions define sequences of other instructions, whereas a low-level instruction corresponds to a direct instruction of the manikin. The set of available instructions that the manikin may perform during a simulation depends on the current state of the manikin and the objects at the assembly station. Thus, properties of objects, such as grasping and mating points, also help define the set of available instructions for the manikin. The order in which the different parts in the assembly operations have to be connected may also be considered when constructing instruction sequences for the manikin. Furthermore, the instruction sequences may be formally verified to ensure that the manikin only performs valid instructions. The language have been implemented in the manikin simulation software IMMA and tested on elementary cases with relevance to industrial applications. The results show that fewer steps are needed to perform a realistic simulation when the language is used compared to manually instructing the manikin. Furthermore, it is also shown that the instructions generated by the language are formally correct.