This research proposes an innovative dental robot with a 7-DOFs parallel-serial hybrid structure to precisely and efficiently execute dental caries removal surgery. The versatile system is distinguished by its unique 7 DOFs, comprising three rotational and three translational movements, with an additional degree for resin injection. This novel hybrid design combines the advantages of serial and parallel mechanical structures enabling highly flexible operations and large rotational capacity within a compact size. According to its multifunctional integrated design, this dental robot can efficiently perform a series of complex surgical tasks, including caries removal, resin injection and light curing. This robot’s two critical design metrics: the local kinematic isotropic index and the local transmission index are determined. In its application to caries removal, the system augmented with commercial haptic feedback devices for leader-follower control, demonstrates its potential in enhancing surgical efficiency and reducing cross-infection risks through its noncontact treatment method. In the experiment, the outcomes of the overall workload are assessed via the NASA task load index (NASA-TLX) and the evaluation of usability is also conducted using system usability scale (SUS). Finally, the robot’s precision is tested to determine its reliability in executing tasks.

The planar parallel robots are widely employed in industrial applications due to simple geometry, few linkage interferences, and a large, reachable workspace. The symmetric geometry can bring significant convenience to parallel robots. The complexity of the mathematic models can be simplified since only one calculation method can be proposed to deal with various kinematic limbs in a parallel manipulator. The symmetric geometry can ease the assembly and maintenance procedures due to the modular design of linkages/joints. A novel 2-translation and 1-rotation (2T1R) parallel robot with symmetric geometry is proposed in this research. There is one closed loop in each kinematic limb, and 18 revolute joints are applied in its planar structure. Both the inverse and direct kinematic models are explored. The first-order relationship between robot inputs and outputs are constructed. Various singularity configurations are obtained based on the Jacobian matrix. The reachable workspace is resolved by the discrete spatial searching methodology, followed by the impacts originating from various linkages. The dexterity analysis of the parallel robot is conducted.

A hybrid robot structure is capable of merging the advantages of both serial and parallel mechanisms, which guarantees its potential in medical robotic fields, especially in dental surgery applications. This paper presents a novel hybrid robot with three translational and three rotational movements. A systematic mechanical design methodology on the basis of the screw theory is proposed to comprehensively search for feasible five-degrees-of-freedom parallel structures. The usage of only planar kinematic joints is beneficial to large translation/rotation reachable workspaces. A parallel robot is chosen to construct a six-degrees-of-freedom hybrid structure. Both the position and velocity relations between the actuators and the mobile platform are established for the parallel unit. Sloping linkages in the curved shape instead of the straight shape are employed to improve the range of motion of the corresponding rotary joints. Both the translation/rotation workspaces are investigated and the manipulability measure is explored. The novel mean manipulator velocity ratio index is developed and examined on this parallel robot. A multi-objective optimization based on an evolutionary algorithm is conducted.

There are limited parallel robots applicable to three-axis grinding machines due to the restricted reachable workspace originating from multiple kinematic chains with spatial kinematic joints. The parallel robot will gain significant potential in the industry if a larger workspace can be achieved. This research introduces a special relationship between upper triangular matrix and parallel robot structures for the purpose of designing a group of novel parallel robots without spatial kinematic joints. The detailed inverse kinematic solution of the selected parallel manipulator is derived in accordance with its straightforward architecture. Several singularity configurations are found on the basis of the first-order kinematic relation. The translational reachable workspace is close to a triangular prism. The dexterity and stiffness performances based on the Jacobian matrix are explored for the chosen parallel manipulator. Both indices display a downward trend as the mobile platform rises higher.