Multi-Robot Manipulation Planning for Forceful Manufacturing Tasks

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Imagine coming back home from a hardware store with planks of wood and working with your friend to manufacture a table for yourself. You will need to collaborate to perform operations such as cutting parts off, inserting nails, drilling holes, and screwing in fasteners. The goal of this project is to get robots to perform similar manufacturing tasks. To do this, a robot team will need to decide how to grasp the workpieces (e.g. wood planks) and how to move to perform these operations. Within this project I will develop planning algorithms that will make such decisions.When the planning algorithms make these decisions, they will need to solve several problems. First, the algorithms must solve geometric problems. Suppose you want to hold a wooden panel such that your friend will drill a hole on a particular surface of it. You would hold the panel such that the surface your friend needs to drill is looking away from you (as opposed to holding the panel such that the surface is looking towards you), so that your friend can position her body across from you and drill comfortably. As you do this you are solving a geometric problem: you grasp the workpiece and position your body such that your collaborator will have the necessary space to position her own body and reach the workpiece to perform the operation. Collaborating robots must solve the same problem: they must grasp workpieces and position themselves such that they can all reach the workpiece and perform operations on it without colliding into each other. As the number of robots required to perform an operation increases, solving the geometric problem becomes harder and harder. Second, the algorithms must solve stability problems due to forces applied on the workpiece. Keeping with the example above, you will probably hold the wooden panel such that you will rest your palms firmly against it close to the point of drilling to be able to resist the forces arising during the operation. This, first of all, requires predicting the direction and magnitude of the forces that will arise before the operation even starts. It also requires planning combinations of contact points on the workpiece and the configurations of your arms, such that you will be able to resist these forces. A robotic planner must solve these problems as well. A particular challenge is solving them simultaneously with the geometric problems mentioned above.Finally, the algorithms must also solve sequential problems because manufacturing a complete product takes much more than a single operation. Rather the robots will need to perform multiple sequential operations such as drilling multiple holes one after the other, then cutting a piece off, and then inserting fasteners. A planner can naively choose to solve each operation separately. However, this would mean that every operation has its own set of grasps and geometric position, planned independently from each other. This would require un-grasping the workpiece after every single operation, and re-grasping and moving it for the next operation. On the other hand, if the algorithms can plan with foresight, e.g. if they can find grasp configurations which obey the geometric and stability constraints not only for the next immediate operation but also for the operations following it, then the final plan would be much more efficient to execute and the robots can avoid the redundant un-grasp/re-grasp operations. Planning multiple operations simultaneously, however, makes the problem even harder because the geometric and stability constraints of future operations must be considered earlier during planning.The primary goal of this project is to develop a planning framework solving all these constraints. The proposed work also involves building a multi-robot system to test our algorithms. This multi-robot system will start with a pile of manufacturing materials and perform operations such as cutting, drilling, and fastening to build products.